\input texinfo @c -*-texinfo-*- @c %**start of header @setfilename guix.info @documentencoding UTF-8 @settitle GNU Guix Reference Manual @c %**end of header @include version.texi @c Identifier of the OpenPGP key used to sign tarballs and such. @set OPENPGP-SIGNING-KEY-ID 3CE464558A84FDC69DB40CFB090B11993D9AEBB5 @set OPENPGP-SIGNING-KEY-URL https://sv.gnu.org/people/viewgpg.php?user_id=15145 @c Base URL for downloads. @set BASE-URL https://ftp.gnu.org/gnu/guix @c The official substitute server used by default. @set SUBSTITUTE-SERVER ci.guix.gnu.org @set SUBSTITUTE-URL https://@value{SUBSTITUTE-SERVER} @copying Copyright @copyright{} 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019, 2020, 2021 Ludovic Courtès@* Copyright @copyright{} 2013, 2014, 2016 Andreas Enge@* Copyright @copyright{} 2013 Nikita Karetnikov@* Copyright @copyright{} 2014, 2015, 2016 Alex Kost@* Copyright @copyright{} 2015, 2016 Mathieu Lirzin@* Copyright @copyright{} 2014 Pierre-Antoine Rault@* Copyright @copyright{} 2015 Taylan Ulrich Bayırlı/Kammer@* Copyright @copyright{} 2015, 2016, 2017, 2019, 2020 Leo Famulari@* Copyright @copyright{} 2015, 2016, 2017, 2018, 2019, 2020 Ricardo Wurmus@* Copyright @copyright{} 2016 Ben Woodcroft@* Copyright @copyright{} 2016, 2017, 2018 Chris Marusich@* Copyright @copyright{} 2016, 2017, 2018, 2019, 2020 Efraim Flashner@* Copyright @copyright{} 2016 John Darrington@* Copyright @copyright{} 2016, 2017 Nikita Gillmann@* Copyright @copyright{} 2016, 2017, 2018, 2019, 2020 Jan Nieuwenhuizen@* Copyright @copyright{} 2016, 2017, 2018, 2019, 2020 Julien Lepiller@* Copyright @copyright{} 2016 Alex ter Weele@* Copyright @copyright{} 2016, 2017, 2018, 2019 Christopher Baines@* Copyright @copyright{} 2017, 2018, 2019 Clément Lassieur@* Copyright @copyright{} 2017, 2018, 2020 Mathieu Othacehe@* Copyright @copyright{} 2017 Federico Beffa@* Copyright @copyright{} 2017, 2018 Carlo Zancanaro@* Copyright @copyright{} 2017 Thomas Danckaert@* Copyright @copyright{} 2017 humanitiesNerd@* Copyright @copyright{} 2017 Christopher Allan Webber@* Copyright @copyright{} 2017, 2018, 2019, 2020 Marius Bakke@* Copyright @copyright{} 2017, 2019, 2020 Hartmut Goebel@* Copyright @copyright{} 2017, 2019, 2020 Maxim Cournoyer@* Copyright @copyright{} 2017, 2018, 2019, 2020 Tobias Geerinckx-Rice@* Copyright @copyright{} 2017 George Clemmer@* Copyright @copyright{} 2017 Andy Wingo@* Copyright @copyright{} 2017, 2018, 2019, 2020 Arun Isaac@* Copyright @copyright{} 2017 nee@* Copyright @copyright{} 2018 Rutger Helling@* Copyright @copyright{} 2018, 2021 Oleg Pykhalov@* Copyright @copyright{} 2018 Mike Gerwitz@* Copyright @copyright{} 2018 Pierre-Antoine Rouby@* Copyright @copyright{} 2018, 2019 Gábor Boskovits@* Copyright @copyright{} 2018, 2019, 2020 Florian Pelz@* Copyright @copyright{} 2018 Laura Lazzati@* Copyright @copyright{} 2018 Alex Vong@* Copyright @copyright{} 2019 Josh Holland@* Copyright @copyright{} 2019, 2020 Diego Nicola Barbato@* Copyright @copyright{} 2019 Ivan Petkov@* Copyright @copyright{} 2019 Jakob L. Kreuze@* Copyright @copyright{} 2019 Kyle Andrews@* Copyright @copyright{} 2019 Alex Griffin@* Copyright @copyright{} 2019, 2020 Guillaume Le Vaillant@* Copyright @copyright{} 2020 Leo Prikler@* Copyright @copyright{} 2019, 2020 Simon Tournier@* Copyright @copyright{} 2020 Wiktor Żelazny@* Copyright @copyright{} 2020 Damien Cassou@* Copyright @copyright{} 2020 Jakub Kądziołka@* Copyright @copyright{} 2020 Jack Hill@* Copyright @copyright{} 2020 Naga Malleswari@* Copyright @copyright{} 2020 Brice Waegeneire@* Copyright @copyright{} 2020 R Veera Kumar@* Copyright @copyright{} 2020 Pierre Langlois@* Copyright @copyright{} 2020 pinoaffe@* Copyright @copyright{} 2020 André Batista@* Copyright @copyright{} 2020 Alexandru-Sergiu Marton@* Copyright @copyright{} 2020 raingloom@* Copyright @copyright{} 2020 Daniel Brooks@* Copyright @copyright{} 2020 John Soo@* Copyright @copyright{} 2020 Jonathan Brielmaier@* Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled ``GNU Free Documentation License''. @end copying @dircategory System administration @direntry * Guix: (guix). Manage installed software and system configuration. * guix package: (guix)Invoking guix package. Installing, removing, and upgrading packages. * guix gc: (guix)Invoking guix gc. Reclaiming unused disk space. * guix pull: (guix)Invoking guix pull. Update the list of available packages. * guix system: (guix)Invoking guix system. Manage the operating system configuration. * guix deploy: (guix)Invoking guix deploy. Manage operating system configurations for remote hosts. @end direntry @dircategory Software development @direntry * guix environment: (guix)Invoking guix environment. Building development environments with Guix. * guix build: (guix)Invoking guix build. Building packages. * guix pack: (guix)Invoking guix pack. Creating binary bundles. @end direntry @titlepage @title GNU Guix Reference Manual @subtitle Using the GNU Guix Functional Package Manager @author The GNU Guix Developers @page @vskip 0pt plus 1filll Edition @value{EDITION} @* @value{UPDATED} @* @insertcopying @end titlepage @contents @c ********************************************************************* @node Top @top GNU Guix This document describes GNU Guix version @value{VERSION}, a functional package management tool written for the GNU system. @c TRANSLATORS: You can replace the following paragraph with information on @c how to join your own translation team and how to report issues with the @c translation. This manual is also available in Simplified Chinese (@pxref{Top,,, guix.zh_CN, GNU Guix参考手册}), French (@pxref{Top,,, guix.fr, Manuel de référence de GNU Guix}), German (@pxref{Top,,, guix.de, Referenzhandbuch zu GNU Guix}), Spanish (@pxref{Top,,, guix.es, Manual de referencia de GNU Guix}), and Russian (@pxref{Top,,, guix.ru, Руководство GNU Guix}). If you would like to translate it in your native language, consider joining the @uref{https://translationproject.org/domain/guix-manual.html, Translation Project}. @menu * Introduction:: What is Guix about? * Installation:: Installing Guix. * System Installation:: Installing the whole operating system. * Getting Started:: Your first steps. * Package Management:: Package installation, upgrade, etc. * Channels:: Customizing the package collection. * Development:: Guix-aided software development. * Programming Interface:: Using Guix in Scheme. * Utilities:: Package management commands. * System Configuration:: Configuring the operating system. * Documentation:: Browsing software user manuals. * Installing Debugging Files:: Feeding the debugger. * Security Updates:: Deploying security fixes quickly. * Bootstrapping:: GNU/Linux built from scratch. * Porting:: Targeting another platform or kernel. * Contributing:: Your help needed! * Acknowledgments:: Thanks! * GNU Free Documentation License:: The license of this manual. * Concept Index:: Concepts. * Programming Index:: Data types, functions, and variables. @detailmenu --- The Detailed Node Listing --- Introduction * Managing Software the Guix Way:: What's special. * GNU Distribution:: The packages and tools. Installation * Binary Installation:: Getting Guix running in no time! * Requirements:: Software needed to build and run Guix. * Running the Test Suite:: Testing Guix. * Setting Up the Daemon:: Preparing the build daemon's environment. * Invoking guix-daemon:: Running the build daemon. * Application Setup:: Application-specific setup. * Upgrading Guix:: Upgrading Guix and its build daemon. Setting Up the Daemon * Build Environment Setup:: Preparing the isolated build environment. * Daemon Offload Setup:: Offloading builds to remote machines. * SELinux Support:: Using an SELinux policy for the daemon. System Installation * Limitations:: What you can expect. * Hardware Considerations:: Supported hardware. * USB Stick and DVD Installation:: Preparing the installation medium. * Preparing for Installation:: Networking, partitioning, etc. * Guided Graphical Installation:: Easy graphical installation. * Manual Installation:: Manual installation for wizards. * After System Installation:: When installation succeeded. * Installing Guix in a VM:: Guix System playground. * Building the Installation Image:: How this comes to be. Manual Installation * Keyboard Layout and Networking and Partitioning:: Initial setup. * Proceeding with the Installation:: Installing. Package Management * Features:: How Guix will make your life brighter. * Invoking guix package:: Package installation, removal, etc. * Substitutes:: Downloading pre-built binaries. * Packages with Multiple Outputs:: Single source package, multiple outputs. * Invoking guix gc:: Running the garbage collector. * Invoking guix pull:: Fetching the latest Guix and distribution. * Invoking guix time-machine:: Running an older revision of Guix. * Inferiors:: Interacting with another revision of Guix. * Invoking guix describe:: Display information about your Guix revision. * Invoking guix archive:: Exporting and importing store files. Substitutes * Official Substitute Server:: One particular source of substitutes. * Substitute Server Authorization:: How to enable or disable substitutes. * Getting Substitutes from Other Servers:: Substitute diversity. * Substitute Authentication:: How Guix verifies substitutes. * Proxy Settings:: How to get substitutes via proxy. * Substitution Failure:: What happens when substitution fails. * On Trusting Binaries:: How can you trust that binary blob? Channels * Specifying Additional Channels:: Extending the package collection. * Using a Custom Guix Channel:: Using a customized Guix. * Replicating Guix:: Running the @emph{exact same} Guix. * Channel Authentication:: How Guix verifies what it fetches. * Creating a Channel:: How to write your custom channel. * Package Modules in a Sub-directory:: Specifying the channel's package modules location. * Declaring Channel Dependencies:: How to depend on other channels. * Specifying Channel Authorizations:: Defining channel authors authorizations. * Primary URL:: Distinguishing mirror to original. * Writing Channel News:: Communicating information to channel's users. Development * Invoking guix environment:: Setting up development environments. * Invoking guix pack:: Creating software bundles. * The GCC toolchain:: Working with languages supported by GCC. * Invoking guix git authenticate:: Authenticating Git repositories. Programming Interface * Package Modules:: Packages from the programmer's viewpoint. * Defining Packages:: Defining new packages. * Defining Package Variants:: Customizing packages. * Build Systems:: Specifying how packages are built. * Build Phases:: Phases of the build process of a package. * Build Utilities:: Helpers for your package definitions and more. * The Store:: Manipulating the package store. * Derivations:: Low-level interface to package derivations. * The Store Monad:: Purely functional interface to the store. * G-Expressions:: Manipulating build expressions. * Invoking guix repl:: Programming Guix in Guile. Defining Packages * package Reference:: The package data type. * origin Reference:: The origin data type. Utilities * Invoking guix build:: Building packages from the command line. * Invoking guix edit:: Editing package definitions. * Invoking guix download:: Downloading a file and printing its hash. * Invoking guix hash:: Computing the cryptographic hash of a file. * Invoking guix import:: Importing package definitions. * Invoking guix refresh:: Updating package definitions. * Invoking guix lint:: Finding errors in package definitions. * Invoking guix size:: Profiling disk usage. * Invoking guix graph:: Visualizing the graph of packages. * Invoking guix publish:: Sharing substitutes. * Invoking guix challenge:: Challenging substitute servers. * Invoking guix copy:: Copying to and from a remote store. * Invoking guix container:: Process isolation. * Invoking guix weather:: Assessing substitute availability. * Invoking guix processes:: Listing client processes. Invoking @command{guix build} * Common Build Options:: Build options for most commands. * Package Transformation Options:: Creating variants of packages. * Additional Build Options:: Options specific to 'guix build'. * Debugging Build Failures:: Real life packaging experience. System Configuration * Using the Configuration System:: Customizing your GNU system. * operating-system Reference:: Detail of operating-system declarations. * File Systems:: Configuring file system mounts. * Mapped Devices:: Block device extra processing. * User Accounts:: Specifying user accounts. * Keyboard Layout:: How the system interprets key strokes. * Locales:: Language and cultural convention settings. * Services:: Specifying system services. * Setuid Programs:: Programs running with root privileges. * X.509 Certificates:: Authenticating HTTPS servers. * Name Service Switch:: Configuring libc's name service switch. * Initial RAM Disk:: Linux-Libre bootstrapping. * Bootloader Configuration:: Configuring the boot loader. * Invoking guix system:: Instantiating a system configuration. * Invoking guix deploy:: Deploying a system configuration to a remote host. * Running Guix in a VM:: How to run Guix System in a virtual machine. * Defining Services:: Adding new service definitions. Services * Base Services:: Essential system services. * Scheduled Job Execution:: The mcron service. * Log Rotation:: The rottlog service. * Networking Services:: Network setup, SSH daemon, etc. * Unattended Upgrades:: Automated system upgrades. * X Window:: Graphical display. * Printing Services:: Local and remote printer support. * Desktop Services:: D-Bus and desktop services. * Sound Services:: ALSA and Pulseaudio services. * Database Services:: SQL databases, key-value stores, etc. * Mail Services:: IMAP, POP3, SMTP, and all that. * Messaging Services:: Messaging services. * Telephony Services:: Telephony services. * Monitoring Services:: Monitoring services. * Kerberos Services:: Kerberos services. * LDAP Services:: LDAP services. * Web Services:: Web servers. * Certificate Services:: TLS certificates via Let's Encrypt. * DNS Services:: DNS daemons. * VPN Services:: VPN daemons. * Network File System:: NFS related services. * Continuous Integration:: The Cuirass service. * Power Management Services:: Extending battery life. * Audio Services:: The MPD. * Virtualization Services:: Virtualization services. * Version Control Services:: Providing remote access to Git repositories. * Game Services:: Game servers. * PAM Mount Service:: Service to mount volumes when logging in. * Guix Services:: Services relating specifically to Guix. * Linux Services:: Services tied to the Linux kernel. * Hurd Services:: Services specific for a Hurd System. * Miscellaneous Services:: Other services. Defining Services * Service Composition:: The model for composing services. * Service Types and Services:: Types and services. * Service Reference:: API reference. * Shepherd Services:: A particular type of service. Installing Debugging Files * Separate Debug Info:: Installing 'debug' outputs. * Rebuilding Debug Info:: Building missing debug info. Bootstrapping * Reduced Binary Seed Bootstrap:: A Bootstrap worthy of GNU. * Preparing to Use the Bootstrap Binaries:: Building that what matters most. @end detailmenu @end menu @c ********************************************************************* @node Introduction @chapter Introduction @cindex purpose GNU Guix@footnote{``Guix'' is pronounced like ``geeks'', or ``ɡiːks'' using the international phonetic alphabet (IPA).} is a package management tool for and distribution of the GNU system. Guix makes it easy for unprivileged users to install, upgrade, or remove software packages, to roll back to a previous package set, to build packages from source, and generally assists with the creation and maintenance of software environments. @cindex Guix System @cindex GuixSD, now Guix System @cindex Guix System Distribution, now Guix System You can install GNU@tie{}Guix on top of an existing GNU/Linux system where it complements the available tools without interference (@pxref{Installation}), or you can use it as a standalone operating system distribution, @dfn{Guix@tie{}System}@footnote{We used to refer to Guix System as ``Guix System Distribution'' or ``GuixSD''. We now consider it makes more sense to group everything under the ``Guix'' banner since, after all, Guix System is readily available through the @command{guix system} command, even if you're using a different distro underneath!}. @xref{GNU Distribution}. @menu * Managing Software the Guix Way:: What's special. * GNU Distribution:: The packages and tools. @end menu @node Managing Software the Guix Way @section Managing Software the Guix Way @cindex user interfaces Guix provides a command-line package management interface (@pxref{Package Management}), tools to help with software development (@pxref{Development}), command-line utilities for more advanced usage (@pxref{Utilities}), as well as Scheme programming interfaces (@pxref{Programming Interface}). @cindex build daemon Its @dfn{build daemon} is responsible for building packages on behalf of users (@pxref{Setting Up the Daemon}) and for downloading pre-built binaries from authorized sources (@pxref{Substitutes}). @cindex extensibility of the distribution @cindex customization, of packages Guix includes package definitions for many GNU and non-GNU packages, all of which @uref{https://www.gnu.org/philosophy/free-sw.html, respect the user's computing freedom}. It is @emph{extensible}: users can write their own package definitions (@pxref{Defining Packages}) and make them available as independent package modules (@pxref{Package Modules}). It is also @emph{customizable}: users can @emph{derive} specialized package definitions from existing ones, including from the command line (@pxref{Package Transformation Options}). @cindex functional package management @cindex isolation Under the hood, Guix implements the @dfn{functional package management} discipline pioneered by Nix (@pxref{Acknowledgments}). In Guix, the package build and installation process is seen as a @emph{function}, in the mathematical sense. That function takes inputs, such as build scripts, a compiler, and libraries, and returns an installed package. As a pure function, its result depends solely on its inputs---for instance, it cannot refer to software or scripts that were not explicitly passed as inputs. A build function always produces the same result when passed a given set of inputs. It cannot alter the environment of the running system in any way; for instance, it cannot create, modify, or delete files outside of its build and installation directories. This is achieved by running build processes in isolated environments (or @dfn{containers}), where only their explicit inputs are visible. @cindex store The result of package build functions is @dfn{cached} in the file system, in a special directory called @dfn{the store} (@pxref{The Store}). Each package is installed in a directory of its own in the store---by default under @file{/gnu/store}. The directory name contains a hash of all the inputs used to build that package; thus, changing an input yields a different directory name. This approach is the foundation for the salient features of Guix: support for transactional package upgrade and rollback, per-user installation, and garbage collection of packages (@pxref{Features}). @node GNU Distribution @section GNU Distribution @cindex Guix System Guix comes with a distribution of the GNU system consisting entirely of free software@footnote{The term ``free'' here refers to the @url{https://www.gnu.org/philosophy/free-sw.html,freedom provided to users of that software}.}. The distribution can be installed on its own (@pxref{System Installation}), but it is also possible to install Guix as a package manager on top of an installed GNU/Linux system (@pxref{Installation}). When we need to distinguish between the two, we refer to the standalone distribution as Guix@tie{}System. The distribution provides core GNU packages such as GNU libc, GCC, and Binutils, as well as many GNU and non-GNU applications. The complete list of available packages can be browsed @url{https://www.gnu.org/software/guix/packages,on-line} or by running @command{guix package} (@pxref{Invoking guix package}): @example guix package --list-available @end example Our goal is to provide a practical 100% free software distribution of Linux-based and other variants of GNU, with a focus on the promotion and tight integration of GNU components, and an emphasis on programs and tools that help users exert that freedom. Packages are currently available on the following platforms: @table @code @item x86_64-linux Intel/AMD @code{x86_64} architecture, Linux-Libre kernel. @item i686-linux Intel 32-bit architecture (IA32), Linux-Libre kernel. @item armhf-linux ARMv7-A architecture with hard float, Thumb-2 and NEON, using the EABI hard-float application binary interface (ABI), and Linux-Libre kernel. @item aarch64-linux little-endian 64-bit ARMv8-A processors, Linux-Libre kernel. @item i586-gnu @uref{https://hurd.gnu.org, GNU/Hurd} on the Intel 32-bit architecture (IA32). This configuration is experimental and under development. The easiest way for you to give it a try is by setting up an instance of @code{hurd-vm-service-type} on your GNU/Linux machine (@pxref{transparent-emulation-qemu, @code{hurd-vm-service-type}}). @xref{Contributing}, on how to help! @item mips64el-linux (deprecated) little-endian 64-bit MIPS processors, specifically the Loongson series, n32 ABI, and Linux-Libre kernel. This configuration is no longer fully supported; in particular, there is no ongoing work to ensure that this architecture still works. Should someone decide they wish to revive this architecture then the code is still available. @end table With Guix@tie{}System, you @emph{declare} all aspects of the operating system configuration and Guix takes care of instantiating the configuration in a transactional, reproducible, and stateless fashion (@pxref{System Configuration}). Guix System uses the Linux-libre kernel, the Shepherd initialization system (@pxref{Introduction,,, shepherd, The GNU Shepherd Manual}), the well-known GNU utilities and tool chain, as well as the graphical environment or system services of your choice. Guix System is available on all the above platforms except @code{mips64el-linux}. @noindent For information on porting to other architectures or kernels, @pxref{Porting}. Building this distribution is a cooperative effort, and you are invited to join! @xref{Contributing}, for information about how you can help. @c ********************************************************************* @node Installation @chapter Installation @cindex installing Guix @quotation Note We recommend the use of this @uref{https://git.savannah.gnu.org/cgit/guix.git/plain/etc/guix-install.sh, shell installer script} to install Guix on top of a running GNU/Linux system, thereafter called a @dfn{foreign distro}.@footnote{This section is concerned with the installation of the package manager, which can be done on top of a running GNU/Linux system. If, instead, you want to install the complete GNU operating system, @pxref{System Installation}.} The script automates the download, installation, and initial configuration of Guix. It should be run as the root user. @end quotation @cindex foreign distro @cindex directories related to foreign distro When installed on a foreign distro, GNU@tie{}Guix complements the available tools without interference. Its data lives exclusively in two directories, usually @file{/gnu/store} and @file{/var/guix}; other files on your system, such as @file{/etc}, are left untouched. Once installed, Guix can be updated by running @command{guix pull} (@pxref{Invoking guix pull}). If you prefer to perform the installation steps manually or want to tweak them, you may find the following subsections useful. They describe the software requirements of Guix, as well as how to install it manually and get ready to use it. @menu * Binary Installation:: Getting Guix running in no time! * Requirements:: Software needed to build and run Guix. * Running the Test Suite:: Testing Guix. * Setting Up the Daemon:: Preparing the build daemon's environment. * Invoking guix-daemon:: Running the build daemon. * Application Setup:: Application-specific setup. * Upgrading Guix:: Upgrading Guix and its build daemon. @end menu @node Binary Installation @section Binary Installation @cindex installing Guix from binaries @cindex installer script This section describes how to install Guix on an arbitrary system from a self-contained tarball providing binaries for Guix and for all its dependencies. This is often quicker than installing from source, which is described in the next sections. The only requirement is to have GNU@tie{}tar and Xz. @c Note duplicated from the ``Installation'' node. @quotation Note We recommend the use of this @uref{https://git.savannah.gnu.org/cgit/guix.git/plain/etc/guix-install.sh, shell installer script}. The script automates the download, installation, and initial configuration steps described below. It should be run as the root user. As root, you can thus run this: @example cd /tmp wget https://git.savannah.gnu.org/cgit/guix.git/plain/etc/guix-install.sh chmod +x guix-install.sh ./guix-install.sh @end example When you're done, @pxref{Application Setup} for extra configuration you might need, and @ref{Getting Started} for your first steps! @end quotation Installing goes along these lines: @enumerate @item @cindex downloading Guix binary Download the binary tarball from @indicateurl{@value{BASE-URL}/guix-binary-@value{VERSION}.x86_64-linux.tar.xz}, where @code{x86_64-linux} can be replaced with @code{i686-linux} for an @code{i686} (32-bits) machine already running the kernel Linux, and so on (@pxref{GNU Distribution}). @c The following is somewhat duplicated in ``System Installation''. Make sure to download the associated @file{.sig} file and to verify the authenticity of the tarball against it, along these lines: @example $ wget @value{BASE-URL}/guix-binary-@value{VERSION}.x86_64-linux.tar.xz.sig $ gpg --verify guix-binary-@value{VERSION}.x86_64-linux.tar.xz.sig @end example If that command fails because you do not have the required public key, then run this command to import it: @example $ wget @value{OPENPGP-SIGNING-KEY-URL} \ -qO - | gpg --import - @end example @noindent and rerun the @code{gpg --verify} command. Take note that a warning like ``This key is not certified with a trusted signature!'' is normal. @c end authentication part @item Now, you need to become the @code{root} user. Depending on your distribution, you may have to run @code{su -} or @code{sudo -i}. As @code{root}, run: @example # cd /tmp # tar --warning=no-timestamp -xf \ /path/to/guix-binary-@value{VERSION}.x86_64-linux.tar.xz # mv var/guix /var/ && mv gnu / @end example This creates @file{/gnu/store} (@pxref{The Store}) and @file{/var/guix}. The latter contains a ready-to-use profile for @code{root} (see next step). Do @emph{not} unpack the tarball on a working Guix system since that would overwrite its own essential files. The @option{--warning=no-timestamp} option makes sure GNU@tie{}tar does not emit warnings about ``implausibly old time stamps'' (such warnings were triggered by GNU@tie{}tar 1.26 and older; recent versions are fine). They stem from the fact that all the files in the archive have their modification time set to 1 (which means January 1st, 1970). This is done on purpose to make sure the archive content is independent of its creation time, thus making it reproducible. @item Make the profile available under @file{~root/.config/guix/current}, which is where @command{guix pull} will install updates (@pxref{Invoking guix pull}): @example # mkdir -p ~root/.config/guix # ln -sf /var/guix/profiles/per-user/root/current-guix \ ~root/.config/guix/current @end example Source @file{etc/profile} to augment @env{PATH} and other relevant environment variables: @example # GUIX_PROFILE="`echo ~root`/.config/guix/current" ; \ source $GUIX_PROFILE/etc/profile @end example @item Create the group and user accounts for build users as explained below (@pxref{Build Environment Setup}). @item Run the daemon, and set it to automatically start on boot. If your host distro uses the systemd init system, this can be achieved with these commands: @c Versions of systemd that supported symlinked service files are not @c yet widely deployed, so we should suggest that users copy the service @c files into place. @c @c See this thread for more information: @c https://lists.gnu.org/archive/html/guix-devel/2017-01/msg01199.html @example # cp ~root/.config/guix/current/lib/systemd/system/gnu-store.mount \ ~root/.config/guix/current/lib/systemd/system/guix-daemon.service \ /etc/systemd/system/ # systemctl enable --now gnu-store.mount guix-daemon @end example If your host distro uses the Upstart init system: @example # initctl reload-configuration # cp ~root/.config/guix/current/lib/upstart/system/guix-daemon.conf \ /etc/init/ # start guix-daemon @end example Otherwise, you can still start the daemon manually with: @example # ~root/.config/guix/current/bin/guix-daemon \ --build-users-group=guixbuild @end example @item Make the @command{guix} command available to other users on the machine, for instance with: @example # mkdir -p /usr/local/bin # cd /usr/local/bin # ln -s /var/guix/profiles/per-user/root/current-guix/bin/guix @end example It is also a good idea to make the Info version of this manual available there: @example # mkdir -p /usr/local/share/info # cd /usr/local/share/info # for i in /var/guix/profiles/per-user/root/current-guix/share/info/* ; do ln -s $i ; done @end example That way, assuming @file{/usr/local/share/info} is in the search path, running @command{info guix} will open this manual (@pxref{Other Info Directories,,, texinfo, GNU Texinfo}, for more details on changing the Info search path). @item @cindex substitutes, authorization thereof To use substitutes from @code{@value{SUBSTITUTE-SERVER}} or one of its mirrors (@pxref{Substitutes}), authorize them: @example # guix archive --authorize < \ ~root/.config/guix/current/share/guix/@value{SUBSTITUTE-SERVER}.pub @end example @item Each user may need to perform a few additional steps to make their Guix environment ready for use, @pxref{Application Setup}. @end enumerate Voilà, the installation is complete! You can confirm that Guix is working by installing a sample package into the root profile: @example # guix install hello @end example The binary installation tarball can be (re)produced and verified simply by running the following command in the Guix source tree: @example make guix-binary.@var{system}.tar.xz @end example @noindent ...@: which, in turn, runs: @example guix pack -s @var{system} --localstatedir \ --profile-name=current-guix guix @end example @xref{Invoking guix pack}, for more info on this handy tool. @node Requirements @section Requirements This section lists requirements when building Guix from source. The build procedure for Guix is the same as for other GNU software, and is not covered here. Please see the files @file{README} and @file{INSTALL} in the Guix source tree for additional details. @cindex official website GNU Guix is available for download from its website at @url{https://www.gnu.org/software/guix/}. GNU Guix depends on the following packages: @itemize @item @url{https://gnu.org/software/guile/, GNU Guile}, version 3.0.x or 2.2.x; @item @url{https://notabug.org/cwebber/guile-gcrypt, Guile-Gcrypt}, version 0.1.0 or later; @item @uref{https://gnutls.org/, GnuTLS}, specifically its Guile bindings (@pxref{Guile Preparations, how to install the GnuTLS bindings for Guile,, gnutls-guile, GnuTLS-Guile}); @item @uref{https://notabug.org/guile-sqlite3/guile-sqlite3, Guile-SQLite3}, version 0.1.0 or later; @item @uref{https://notabug.org/guile-zlib/guile-zlib, Guile-zlib}; @item @uref{https://notabug.org/guile-lzlib/guile-lzlib, Guile-lzlib}; @item @uref{https://www.nongnu.org/guile-avahi/, Guile-Avahi}; @item @c FIXME: Specify a version number once a release has been made. @uref{https://gitlab.com/guile-git/guile-git, Guile-Git}, version 0.3.0 or later; @item @uref{https://savannah.nongnu.org/projects/guile-json/, Guile-JSON} 4.3.0 or later; @item @url{https://www.gnu.org/software/make/, GNU Make}. @end itemize The following dependencies are optional: @itemize @item @c Note: We need at least 0.13.0 for #:nodelay. Support for build offloading (@pxref{Daemon Offload Setup}) and @command{guix copy} (@pxref{Invoking guix copy}) depends on @uref{https://github.com/artyom-poptsov/guile-ssh, Guile-SSH}, version 0.13.0 or later. @item @uref{https://ngyro.com/software/guile-semver.html, Guile-Semver} for the @code{crate} importer (@pxref{Invoking guix import}). @item When @url{http://www.bzip.org, libbz2} is available, @command{guix-daemon} can use it to compress build logs. @end itemize Unless @option{--disable-daemon} was passed to @command{configure}, the following packages are also needed: @itemize @item @url{https://gnupg.org/, GNU libgcrypt}; @item @url{https://sqlite.org, SQLite 3}; @item @url{https://gcc.gnu.org, GCC's g++}, with support for the C++11 standard. @end itemize @cindex state directory When configuring Guix on a system that already has a Guix installation, be sure to specify the same state directory as the existing installation using the @option{--localstatedir} option of the @command{configure} script (@pxref{Directory Variables, @code{localstatedir},, standards, GNU Coding Standards}). Usually, this @var{localstatedir} option is set to the value @file{/var}. The @command{configure} script protects against unintended misconfiguration of @var{localstatedir} so you do not inadvertently corrupt your store (@pxref{The Store}). @node Running the Test Suite @section Running the Test Suite @cindex test suite After a successful @command{configure} and @code{make} run, it is a good idea to run the test suite. It can help catch issues with the setup or environment, or bugs in Guix itself---and really, reporting test failures is a good way to help improve the software. To run the test suite, type: @example make check @end example Test cases can run in parallel: you can use the @code{-j} option of GNU@tie{}make to speed things up. The first run may take a few minutes on a recent machine; subsequent runs will be faster because the store that is created for test purposes will already have various things in cache. It is also possible to run a subset of the tests by defining the @code{TESTS} makefile variable as in this example: @example make check TESTS="tests/store.scm tests/cpio.scm" @end example By default, tests results are displayed at a file level. In order to see the details of every individual test cases, it is possible to define the @code{SCM_LOG_DRIVER_FLAGS} makefile variable as in this example: @example make check TESTS="tests/base64.scm" SCM_LOG_DRIVER_FLAGS="--brief=no" @end example Upon failure, please email @email{bug-guix@@gnu.org} and attach the @file{test-suite.log} file. Please specify the Guix version being used as well as version numbers of the dependencies (@pxref{Requirements}) in your message. Guix also comes with a whole-system test suite that tests complete Guix System instances. It can only run on systems where Guix is already installed, using: @example make check-system @end example @noindent or, again, by defining @code{TESTS} to select a subset of tests to run: @example make check-system TESTS="basic mcron" @end example These system tests are defined in the @code{(gnu tests @dots{})} modules. They work by running the operating systems under test with lightweight instrumentation in a virtual machine (VM). They can be computationally intensive or rather cheap, depending on whether substitutes are available for their dependencies (@pxref{Substitutes}). Some of them require a lot of storage space to hold VM images. Again in case of test failures, please send @email{bug-guix@@gnu.org} all the details. @node Setting Up the Daemon @section Setting Up the Daemon @cindex daemon Operations such as building a package or running the garbage collector are all performed by a specialized process, the @dfn{build daemon}, on behalf of clients. Only the daemon may access the store and its associated database. Thus, any operation that manipulates the store goes through the daemon. For instance, command-line tools such as @command{guix package} and @command{guix build} communicate with the daemon (@i{via} remote procedure calls) to instruct it what to do. The following sections explain how to prepare the build daemon's environment. See also @ref{Substitutes}, for information on how to allow the daemon to download pre-built binaries. @menu * Build Environment Setup:: Preparing the isolated build environment. * Daemon Offload Setup:: Offloading builds to remote machines. * SELinux Support:: Using an SELinux policy for the daemon. @end menu @node Build Environment Setup @subsection Build Environment Setup @cindex build environment In a standard multi-user setup, Guix and its daemon---the @command{guix-daemon} program---are installed by the system administrator; @file{/gnu/store} is owned by @code{root} and @command{guix-daemon} runs as @code{root}. Unprivileged users may use Guix tools to build packages or otherwise access the store, and the daemon will do it on their behalf, ensuring that the store is kept in a consistent state, and allowing built packages to be shared among users. @cindex build users When @command{guix-daemon} runs as @code{root}, you may not want package build processes themselves to run as @code{root} too, for obvious security reasons. To avoid that, a special pool of @dfn{build users} should be created for use by build processes started by the daemon. These build users need not have a shell and a home directory: they will just be used when the daemon drops @code{root} privileges in build processes. Having several such users allows the daemon to launch distinct build processes under separate UIDs, which guarantees that they do not interfere with each other---an essential feature since builds are regarded as pure functions (@pxref{Introduction}). On a GNU/Linux system, a build user pool may be created like this (using Bash syntax and the @code{shadow} commands): @c See https://lists.gnu.org/archive/html/bug-guix/2013-01/msg00239.html @c for why `-G' is needed. @example # groupadd --system guixbuild # for i in `seq -w 1 10`; do useradd -g guixbuild -G guixbuild \ -d /var/empty -s `which nologin` \ -c "Guix build user $i" --system \ guixbuilder$i; done @end example @noindent The number of build users determines how many build jobs may run in parallel, as specified by the @option{--max-jobs} option (@pxref{Invoking guix-daemon, @option{--max-jobs}}). To use @command{guix system vm} and related commands, you may need to add the build users to the @code{kvm} group so they can access @file{/dev/kvm}, using @code{-G guixbuild,kvm} instead of @code{-G guixbuild} (@pxref{Invoking guix system}). The @code{guix-daemon} program may then be run as @code{root} with the following command@footnote{If your machine uses the systemd init system, dropping the @file{@var{prefix}/lib/systemd/system/guix-daemon.service} file in @file{/etc/systemd/system} will ensure that @command{guix-daemon} is automatically started. Similarly, if your machine uses the Upstart init system, drop the @file{@var{prefix}/lib/upstart/system/guix-daemon.conf} file in @file{/etc/init}.}: @example # guix-daemon --build-users-group=guixbuild @end example @cindex chroot @noindent This way, the daemon starts build processes in a chroot, under one of the @code{guixbuilder} users. On GNU/Linux, by default, the chroot environment contains nothing but: @c Keep this list in sync with libstore/build.cc! ----------------------- @itemize @item a minimal @code{/dev} directory, created mostly independently from the host @code{/dev}@footnote{``Mostly'', because while the set of files that appear in the chroot's @code{/dev} is fixed, most of these files can only be created if the host has them.}; @item the @code{/proc} directory; it only shows the processes of the container since a separate PID name space is used; @item @file{/etc/passwd} with an entry for the current user and an entry for user @file{nobody}; @item @file{/etc/group} with an entry for the user's group; @item @file{/etc/hosts} with an entry that maps @code{localhost} to @code{127.0.0.1}; @item a writable @file{/tmp} directory. @end itemize You can influence the directory where the daemon stores build trees @i{via} the @env{TMPDIR} environment variable. However, the build tree within the chroot is always called @file{/tmp/guix-build-@var{name}.drv-0}, where @var{name} is the derivation name---e.g., @code{coreutils-8.24}. This way, the value of @env{TMPDIR} does not leak inside build environments, which avoids discrepancies in cases where build processes capture the name of their build tree. @vindex http_proxy @vindex https_proxy The daemon also honors the @env{http_proxy} and @env{https_proxy} environment variables for HTTP and HTTPS downloads it performs, be it for fixed-output derivations (@pxref{Derivations}) or for substitutes (@pxref{Substitutes}). If you are installing Guix as an unprivileged user, it is still possible to run @command{guix-daemon} provided you pass @option{--disable-chroot}. However, build processes will not be isolated from one another, and not from the rest of the system. Thus, build processes may interfere with each other, and may access programs, libraries, and other files available on the system---making it much harder to view them as @emph{pure} functions. @node Daemon Offload Setup @subsection Using the Offload Facility @cindex offloading @cindex build hook When desired, the build daemon can @dfn{offload} derivation builds to other machines running Guix, using the @code{offload} @dfn{build hook}@footnote{This feature is available only when @uref{https://github.com/artyom-poptsov/guile-ssh, Guile-SSH} is present.}. When that feature is enabled, a list of user-specified build machines is read from @file{/etc/guix/machines.scm}; every time a build is requested, for instance via @code{guix build}, the daemon attempts to offload it to one of the machines that satisfy the constraints of the derivation, in particular its system types---e.g., @code{x86_64-linux}. A single machine can have multiple system types, either because its architecture natively supports it, via emulation (@pxref{transparent-emulation-qemu, Transparent Emulation with QEMU}), or both. Missing prerequisites for the build are copied over SSH to the target machine, which then proceeds with the build; upon success the output(s) of the build are copied back to the initial machine. The offload facility comes with a basic scheduler that attempts to select the best machine. The best machine is chosen among the available machines based on criteria such as: @enumerate @item The availability of a build slot. A build machine can have as many build slots (connections) as the value of the @code{parallel-builds} field of its @code{build-machine} object. @item Its relative speed, as defined via the @code{speed} field of its @code{build-machine} object. @item Its load. The normalized machine load must be lower than a threshold value, configurable via the @code{overload-threshold} field of its @code{build-machine} object. @item Disk space availability. More than a 100 MiB must be available. @end enumerate The @file{/etc/guix/machines.scm} file typically looks like this: @lisp (list (build-machine (name "eightysix.example.org") (systems (list "x86_64-linux" "i686-linux")) (host-key "ssh-ed25519 AAAAC3Nza@dots{}") (user "bob") (speed 2.)) ;incredibly fast! (build-machine (name "armeight.example.org") (systems (list "aarch64-linux")) (host-key "ssh-rsa AAAAB3Nza@dots{}") (user "alice") (private-key (string-append (getenv "HOME") "/.ssh/identity-for-guix")))) @end lisp @noindent In the example above we specify a list of two build machines, one for the @code{x86_64} and @code{i686} architectures and one for the @code{aarch64} architecture. In fact, this file is---not surprisingly!---a Scheme file that is evaluated when the @code{offload} hook is started. Its return value must be a list of @code{build-machine} objects. While this example shows a fixed list of build machines, one could imagine, say, using DNS-SD to return a list of potential build machines discovered in the local network (@pxref{Introduction, Guile-Avahi,, guile-avahi, Using Avahi in Guile Scheme Programs}). The @code{build-machine} data type is detailed below. @deftp {Data Type} build-machine This data type represents build machines to which the daemon may offload builds. The important fields are: @table @code @item name The host name of the remote machine. @item systems The system types the remote machine supports---e.g., @code{(list "x86_64-linux" "i686-linux")}. @item user The user account to use when connecting to the remote machine over SSH. Note that the SSH key pair must @emph{not} be passphrase-protected, to allow non-interactive logins. @item host-key This must be the machine's SSH @dfn{public host key} in OpenSSH format. This is used to authenticate the machine when we connect to it. It is a long string that looks like this: @example ssh-ed25519 AAAAC3NzaC@dots{}mde+UhL hint@@example.org @end example If the machine is running the OpenSSH daemon, @command{sshd}, the host key can be found in a file such as @file{/etc/ssh/ssh_host_ed25519_key.pub}. If the machine is running the SSH daemon of GNU@tie{}lsh, @command{lshd}, the host key is in @file{/etc/lsh/host-key.pub} or a similar file. It can be converted to the OpenSSH format using @command{lsh-export-key} (@pxref{Converting keys,,, lsh, LSH Manual}): @example $ lsh-export-key --openssh < /etc/lsh/host-key.pub ssh-rsa AAAAB3NzaC1yc2EAAAAEOp8FoQAAAQEAs1eB46LV@dots{} @end example @end table A number of optional fields may be specified: @table @asis @item @code{port} (default: @code{22}) Port number of SSH server on the machine. @item @code{private-key} (default: @file{~root/.ssh/id_rsa}) The SSH private key file to use when connecting to the machine, in OpenSSH format. This key must not be protected with a passphrase. Note that the default value is the private key @emph{of the root account}. Make sure it exists if you use the default. @item @code{compression} (default: @code{"zlib@@openssh.com,zlib"}) @itemx @code{compression-level} (default: @code{3}) The SSH-level compression methods and compression level requested. Note that offloading relies on SSH compression to reduce bandwidth usage when transferring files to and from build machines. @item @code{daemon-socket} (default: @code{"/var/guix/daemon-socket/socket"}) File name of the Unix-domain socket @command{guix-daemon} is listening to on that machine. @item @code{overload-threshold} (default: @code{0.6}) The load threshold above which a potential offload machine is disregarded by the offload scheduler. The value roughly translates to the total processor usage of the build machine, ranging from 0.0 (0%) to 1.0 (100%). It can also be disabled by setting @code{overload-threshold} to @code{#f}. @item @code{parallel-builds} (default: @code{1}) The number of builds that may run in parallel on the machine. @item @code{speed} (default: @code{1.0}) A ``relative speed factor''. The offload scheduler will tend to prefer machines with a higher speed factor. @item @code{features} (default: @code{'()}) A list of strings denoting specific features supported by the machine. An example is @code{"kvm"} for machines that have the KVM Linux modules and corresponding hardware support. Derivations can request features by name, and they will be scheduled on matching build machines. @end table @end deftp The @command{guix} command must be in the search path on the build machines. You can check whether this is the case by running: @example ssh build-machine guix repl --version @end example There is one last thing to do once @file{machines.scm} is in place. As explained above, when offloading, files are transferred back and forth between the machine stores. For this to work, you first need to generate a key pair on each machine to allow the daemon to export signed archives of files from the store (@pxref{Invoking guix archive}): @example # guix archive --generate-key @end example @noindent Each build machine must authorize the key of the master machine so that it accepts store items it receives from the master: @example # guix archive --authorize < master-public-key.txt @end example @noindent Likewise, the master machine must authorize the key of each build machine. All the fuss with keys is here to express pairwise mutual trust relations between the master and the build machines. Concretely, when the master receives files from a build machine (and @i{vice versa}), its build daemon can make sure they are genuine, have not been tampered with, and that they are signed by an authorized key. @cindex offload test To test whether your setup is operational, run this command on the master node: @example # guix offload test @end example This will attempt to connect to each of the build machines specified in @file{/etc/guix/machines.scm}, make sure Guix is available on each machine, attempt to export to the machine and import from it, and report any error in the process. If you want to test a different machine file, just specify it on the command line: @example # guix offload test machines-qualif.scm @end example Last, you can test the subset of the machines whose name matches a regular expression like this: @example # guix offload test machines.scm '\.gnu\.org$' @end example @cindex offload status To display the current load of all build hosts, run this command on the main node: @example # guix offload status @end example @node SELinux Support @subsection SELinux Support @cindex SELinux, daemon policy @cindex mandatory access control, SELinux @cindex security, guix-daemon Guix includes an SELinux policy file at @file{etc/guix-daemon.cil} that can be installed on a system where SELinux is enabled, in order to label Guix files and to specify the expected behavior of the daemon. Since Guix System does not provide an SELinux base policy, the daemon policy cannot be used on Guix System. @subsubsection Installing the SELinux policy @cindex SELinux, policy installation To install the policy run this command as root: @example semodule -i etc/guix-daemon.cil @end example Then relabel the file system with @code{restorecon} or by a different mechanism provided by your system. Once the policy is installed, the file system has been relabeled, and the daemon has been restarted, it should be running in the @code{guix_daemon_t} context. You can confirm this with the following command: @example ps -Zax | grep guix-daemon @end example Monitor the SELinux log files as you run a command like @code{guix build hello} to convince yourself that SELinux permits all necessary operations. @subsubsection Limitations @cindex SELinux, limitations This policy is not perfect. Here is a list of limitations or quirks that should be considered when deploying the provided SELinux policy for the Guix daemon. @enumerate @item @code{guix_daemon_socket_t} isn’t actually used. None of the socket operations involve contexts that have anything to do with @code{guix_daemon_socket_t}. It doesn’t hurt to have this unused label, but it would be preferrable to define socket rules for only this label. @item @code{guix gc} cannot access arbitrary links to profiles. By design, the file label of the destination of a symlink is independent of the file label of the link itself. Although all profiles under $localstatedir are labelled, the links to these profiles inherit the label of the directory they are in. For links in the user’s home directory this will be @code{user_home_t}. But for links from the root user’s home directory, or @file{/tmp}, or the HTTP server’s working directory, etc, this won’t work. @code{guix gc} would be prevented from reading and following these links. @item The daemon’s feature to listen for TCP connections might no longer work. This might require extra rules, because SELinux treats network sockets differently from files. @item Currently all files with a name matching the regular expression @code{/gnu/store/.+-(guix-.+|profile)/bin/guix-daemon} are assigned the label @code{guix_daemon_exec_t}; this means that @emph{any} file with that name in any profile would be permitted to run in the @code{guix_daemon_t} domain. This is not ideal. An attacker could build a package that provides this executable and convince a user to install and run it, which lifts it into the @code{guix_daemon_t} domain. At that point SELinux could not prevent it from accessing files that are allowed for processes in that domain. You will need to relabel the store directory after all upgrades to @file{guix-daemon}, such as after running @code{guix pull}. Assuming the store is in @file{/gnu}, you can do this with @code{restorecon -vR /gnu}, or by other means provided by your operating system. We could generate a much more restrictive policy at installation time, so that only the @emph{exact} file name of the currently installed @code{guix-daemon} executable would be labelled with @code{guix_daemon_exec_t}, instead of using a broad regular expression. The downside is that root would have to install or upgrade the policy at installation time whenever the Guix package that provides the effectively running @code{guix-daemon} executable is upgraded. @end enumerate @node Invoking guix-daemon @section Invoking @command{guix-daemon} The @command{guix-daemon} program implements all the functionality to access the store. This includes launching build processes, running the garbage collector, querying the availability of a build result, etc. It is normally run as @code{root} like this: @example # guix-daemon --build-users-group=guixbuild @end example @noindent For details on how to set it up, @pxref{Setting Up the Daemon}. @cindex chroot @cindex container, build environment @cindex build environment @cindex reproducible builds By default, @command{guix-daemon} launches build processes under different UIDs, taken from the build group specified with @option{--build-users-group}. In addition, each build process is run in a chroot environment that only contains the subset of the store that the build process depends on, as specified by its derivation (@pxref{Programming Interface, derivation}), plus a set of specific system directories. By default, the latter contains @file{/dev} and @file{/dev/pts}. Furthermore, on GNU/Linux, the build environment is a @dfn{container}: in addition to having its own file system tree, it has a separate mount name space, its own PID name space, network name space, etc. This helps achieve reproducible builds (@pxref{Features}). When the daemon performs a build on behalf of the user, it creates a build directory under @file{/tmp} or under the directory specified by its @env{TMPDIR} environment variable. This directory is shared with the container for the duration of the build, though within the container, the build tree is always called @file{/tmp/guix-build-@var{name}.drv-0}. The build directory is automatically deleted upon completion, unless the build failed and the client specified @option{--keep-failed} (@pxref{Invoking guix build, @option{--keep-failed}}). The daemon listens for connections and spawns one sub-process for each session started by a client (one of the @command{guix} sub-commands). The @command{guix processes} command allows you to get an overview of the activity on your system by viewing each of the active sessions and clients. @xref{Invoking guix processes}, for more information. The following command-line options are supported: @table @code @item --build-users-group=@var{group} Take users from @var{group} to run build processes (@pxref{Setting Up the Daemon, build users}). @item --no-substitutes @cindex substitutes Do not use substitutes for build products. That is, always build things locally instead of allowing downloads of pre-built binaries (@pxref{Substitutes}). When the daemon runs with @option{--no-substitutes}, clients can still explicitly enable substitution @i{via} the @code{set-build-options} remote procedure call (@pxref{The Store}). @anchor{daemon-substitute-urls} @item --substitute-urls=@var{urls} Consider @var{urls} the default whitespace-separated list of substitute source URLs. When this option is omitted, @indicateurl{https://@value{SUBSTITUTE-SERVER}} is used. This means that substitutes may be downloaded from @var{urls}, as long as they are signed by a trusted signature (@pxref{Substitutes}). @xref{Getting Substitutes from Other Servers}, for more information on how to configure the daemon to get substitutes from other servers. @cindex offloading @item --no-offload Do not use offload builds to other machines (@pxref{Daemon Offload Setup}). That is, always build things locally instead of offloading builds to remote machines. @item --cache-failures Cache build failures. By default, only successful builds are cached. When this option is used, @command{guix gc --list-failures} can be used to query the set of store items marked as failed; @command{guix gc --clear-failures} removes store items from the set of cached failures. @xref{Invoking guix gc}. @item --cores=@var{n} @itemx -c @var{n} Use @var{n} CPU cores to build each derivation; @code{0} means as many as available. The default value is @code{0}, but it may be overridden by clients, such as the @option{--cores} option of @command{guix build} (@pxref{Invoking guix build}). The effect is to define the @env{NIX_BUILD_CORES} environment variable in the build process, which can then use it to exploit internal parallelism---for instance, by running @code{make -j$NIX_BUILD_CORES}. @item --max-jobs=@var{n} @itemx -M @var{n} Allow at most @var{n} build jobs in parallel. The default value is @code{1}. Setting it to @code{0} means that no builds will be performed locally; instead, the daemon will offload builds (@pxref{Daemon Offload Setup}), or simply fail. @item --max-silent-time=@var{seconds} When the build or substitution process remains silent for more than @var{seconds}, terminate it and report a build failure. The default value is @code{0}, which disables the timeout. The value specified here can be overridden by clients (@pxref{Common Build Options, @option{--max-silent-time}}). @item --timeout=@var{seconds} Likewise, when the build or substitution process lasts for more than @var{seconds}, terminate it and report a build failure. The default value is @code{0}, which disables the timeout. The value specified here can be overridden by clients (@pxref{Common Build Options, @option{--timeout}}). @item --rounds=@var{N} Build each derivation @var{n} times in a row, and raise an error if consecutive build results are not bit-for-bit identical. Note that this setting can be overridden by clients such as @command{guix build} (@pxref{Invoking guix build}). When used in conjunction with @option{--keep-failed}, the differing output is kept in the store, under @file{/gnu/store/@dots{}-check}. This makes it easy to look for differences between the two results. @item --debug Produce debugging output. This is useful to debug daemon start-up issues, but then it may be overridden by clients, for example the @option{--verbosity} option of @command{guix build} (@pxref{Invoking guix build}). @item --chroot-directory=@var{dir} Add @var{dir} to the build chroot. Doing this may change the result of build processes---for instance if they use optional dependencies found in @var{dir} when it is available, and not otherwise. For that reason, it is not recommended to do so. Instead, make sure that each derivation declares all the inputs that it needs. @item --disable-chroot Disable chroot builds. Using this option is not recommended since, again, it would allow build processes to gain access to undeclared dependencies. It is necessary, though, when @command{guix-daemon} is running under an unprivileged user account. @item --log-compression=@var{type} Compress build logs according to @var{type}, one of @code{gzip}, @code{bzip2}, or @code{none}. Unless @option{--lose-logs} is used, all the build logs are kept in the @var{localstatedir}. To save space, the daemon automatically compresses them with Bzip2 by default. @item --discover[=yes|no] Whether to discover substitute servers on the local network using mDNS and DNS-SD. This feature is still experimental. However, here are a few considerations. @enumerate @item It might be faster/less expensive than fetching from remote servers; @item There are no security risks, only genuine substitutes will be used (@pxref{Substitute Authentication}); @item An attacker advertising @command{guix publish} on your LAN cannot serve you malicious binaries, but they can learn what software you’re installing; @item Servers may serve substitute over HTTP, unencrypted, so anyone on the LAN can see what software you’re installing. @end enumerate It is also possible to enable or disable substitute server discovery at run-time by running: @example herd discover guix-daemon on herd discover guix-daemon off @end example @item --disable-deduplication @cindex deduplication Disable automatic file ``deduplication'' in the store. By default, files added to the store are automatically ``deduplicated'': if a newly added file is identical to another one found in the store, the daemon makes the new file a hard link to the other file. This can noticeably reduce disk usage, at the expense of slightly increased input/output load at the end of a build process. This option disables this optimization. @item --gc-keep-outputs[=yes|no] Tell whether the garbage collector (GC) must keep outputs of live derivations. @cindex GC roots @cindex garbage collector roots When set to @code{yes}, the GC will keep the outputs of any live derivation available in the store---the @file{.drv} files. The default is @code{no}, meaning that derivation outputs are kept only if they are reachable from a GC root. @xref{Invoking guix gc}, for more on GC roots. @item --gc-keep-derivations[=yes|no] Tell whether the garbage collector (GC) must keep derivations corresponding to live outputs. When set to @code{yes}, as is the case by default, the GC keeps derivations---i.e., @file{.drv} files---as long as at least one of their outputs is live. This allows users to keep track of the origins of items in their store. Setting it to @code{no} saves a bit of disk space. In this way, setting @option{--gc-keep-derivations} to @code{yes} causes liveness to flow from outputs to derivations, and setting @option{--gc-keep-outputs} to @code{yes} causes liveness to flow from derivations to outputs. When both are set to @code{yes}, the effect is to keep all the build prerequisites (the sources, compiler, libraries, and other build-time tools) of live objects in the store, regardless of whether these prerequisites are reachable from a GC root. This is convenient for developers since it saves rebuilds or downloads. @item --impersonate-linux-2.6 On Linux-based systems, impersonate Linux 2.6. This means that the kernel's @command{uname} system call will report 2.6 as the release number. This might be helpful to build programs that (usually wrongfully) depend on the kernel version number. @item --lose-logs Do not keep build logs. By default they are kept under @file{@var{localstatedir}/guix/log}. @item --system=@var{system} Assume @var{system} as the current system type. By default it is the architecture/kernel pair found at configure time, such as @code{x86_64-linux}. @item --listen=@var{endpoint} Listen for connections on @var{endpoint}. @var{endpoint} is interpreted as the file name of a Unix-domain socket if it starts with @code{/} (slash sign). Otherwise, @var{endpoint} is interpreted as a host name or host name and port to listen to. Here are a few examples: @table @code @item --listen=/gnu/var/daemon Listen for connections on the @file{/gnu/var/daemon} Unix-domain socket, creating it if needed. @item --listen=localhost @cindex daemon, remote access @cindex remote access to the daemon @cindex daemon, cluster setup @cindex clusters, daemon setup Listen for TCP connections on the network interface corresponding to @code{localhost}, on port 44146. @item --listen=128.0.0.42:1234 Listen for TCP connections on the network interface corresponding to @code{128.0.0.42}, on port 1234. @end table This option can be repeated multiple times, in which case @command{guix-daemon} accepts connections on all the specified endpoints. Users can tell client commands what endpoint to connect to by setting the @env{GUIX_DAEMON_SOCKET} environment variable (@pxref{The Store, @env{GUIX_DAEMON_SOCKET}}). @quotation Note The daemon protocol is @emph{unauthenticated and unencrypted}. Using @option{--listen=@var{host}} is suitable on local networks, such as clusters, where only trusted nodes may connect to the build daemon. In other cases where remote access to the daemon is needed, we recommend using Unix-domain sockets along with SSH. @end quotation When @option{--listen} is omitted, @command{guix-daemon} listens for connections on the Unix-domain socket located at @file{@var{localstatedir}/guix/daemon-socket/socket}. @end table @node Application Setup @section Application Setup @cindex foreign distro When using Guix on top of GNU/Linux distribution other than Guix System---a so-called @dfn{foreign distro}---a few additional steps are needed to get everything in place. Here are some of them. @subsection Locales @anchor{locales-and-locpath} @cindex locales, when not on Guix System @vindex LOCPATH @vindex GUIX_LOCPATH Packages installed @i{via} Guix will not use the locale data of the host system. Instead, you must first install one of the locale packages available with Guix and then define the @env{GUIX_LOCPATH} environment variable: @example $ guix install glibc-locales $ export GUIX_LOCPATH=$HOME/.guix-profile/lib/locale @end example Note that the @code{glibc-locales} package contains data for all the locales supported by the GNU@tie{}libc and weighs in at around 917@tie{}MiB. Alternatively, the @code{glibc-utf8-locales} is smaller but limited to a few UTF-8 locales. The @env{GUIX_LOCPATH} variable plays a role similar to @env{LOCPATH} (@pxref{Locale Names, @env{LOCPATH},, libc, The GNU C Library Reference Manual}). There are two important differences though: @enumerate @item @env{GUIX_LOCPATH} is honored only by the libc in Guix, and not by the libc provided by foreign distros. Thus, using @env{GUIX_LOCPATH} allows you to make sure the programs of the foreign distro will not end up loading incompatible locale data. @item libc suffixes each entry of @env{GUIX_LOCPATH} with @code{/X.Y}, where @code{X.Y} is the libc version---e.g., @code{2.22}. This means that, should your Guix profile contain a mixture of programs linked against different libc version, each libc version will only try to load locale data in the right format. @end enumerate This is important because the locale data format used by different libc versions may be incompatible. @subsection Name Service Switch @cindex name service switch, glibc @cindex NSS (name service switch), glibc @cindex nscd (name service caching daemon) @cindex name service caching daemon (nscd) When using Guix on a foreign distro, we @emph{strongly recommend} that the system run the GNU C library's @dfn{name service cache daemon}, @command{nscd}, which should be listening on the @file{/var/run/nscd/socket} socket. Failing to do that, applications installed with Guix may fail to look up host names or user accounts, or may even crash. The next paragraphs explain why. @cindex @file{nsswitch.conf} The GNU C library implements a @dfn{name service switch} (NSS), which is an extensible mechanism for ``name lookups'' in general: host name resolution, user accounts, and more (@pxref{Name Service Switch,,, libc, The GNU C Library Reference Manual}). @cindex Network information service (NIS) @cindex NIS (Network information service) Being extensible, the NSS supports @dfn{plugins}, which provide new name lookup implementations: for example, the @code{nss-mdns} plugin allow resolution of @code{.local} host names, the @code{nis} plugin allows user account lookup using the Network information service (NIS), and so on. These extra ``lookup services'' are configured system-wide in @file{/etc/nsswitch.conf}, and all the programs running on the system honor those settings (@pxref{NSS Configuration File,,, libc, The GNU C Reference Manual}). When they perform a name lookup---for instance by calling the @code{getaddrinfo} function in C---applications first try to connect to the nscd; on success, nscd performs name lookups on their behalf. If the nscd is not running, then they perform the name lookup by themselves, by loading the name lookup services into their own address space and running it. These name lookup services---the @file{libnss_*.so} files---are @code{dlopen}'d, but they may come from the host system's C library, rather than from the C library the application is linked against (the C library coming from Guix). And this is where the problem is: if your application is linked against Guix's C library (say, glibc 2.24) and tries to load NSS plugins from another C library (say, @code{libnss_mdns.so} for glibc 2.22), it will likely crash or have its name lookups fail unexpectedly. Running @command{nscd} on the system, among other advantages, eliminates this binary incompatibility problem because those @code{libnss_*.so} files are loaded in the @command{nscd} process, not in applications themselves. @subsection X11 Fonts @cindex fonts The majority of graphical applications use Fontconfig to locate and load fonts and perform X11-client-side rendering. The @code{fontconfig} package in Guix looks for fonts in @file{$HOME/.guix-profile} by default. Thus, to allow graphical applications installed with Guix to display fonts, you have to install fonts with Guix as well. Essential font packages include @code{gs-fonts}, @code{font-dejavu}, and @code{font-gnu-freefont}. @cindex @code{fc-cache} @cindex font cache Once you have installed or removed fonts, or when you notice an application that does not find fonts, you may need to install Fontconfig and to force an update of its font cache by running: @example guix install fontconfig fc-cache -rv @end example To display text written in Chinese languages, Japanese, or Korean in graphical applications, consider installing @code{font-adobe-source-han-sans} or @code{font-wqy-zenhei}. The former has multiple outputs, one per language family (@pxref{Packages with Multiple Outputs}). For instance, the following command installs fonts for Chinese languages: @example guix install font-adobe-source-han-sans:cn @end example @cindex @code{xterm} Older programs such as @command{xterm} do not use Fontconfig and instead rely on server-side font rendering. Such programs require to specify a full name of a font using XLFD (X Logical Font Description), like this: @example -*-dejavu sans-medium-r-normal-*-*-100-*-*-*-*-*-1 @end example To be able to use such full names for the TrueType fonts installed in your Guix profile, you need to extend the font path of the X server: @c Note: 'xset' does not accept symlinks so the trick below arranges to @c get at the real directory. See . @example xset +fp $(dirname $(readlink -f ~/.guix-profile/share/fonts/truetype/fonts.dir)) @end example @cindex @code{xlsfonts} After that, you can run @code{xlsfonts} (from @code{xlsfonts} package) to make sure your TrueType fonts are listed there. @subsection X.509 Certificates @cindex @code{nss-certs} The @code{nss-certs} package provides X.509 certificates, which allow programs to authenticate Web servers accessed over HTTPS. When using Guix on a foreign distro, you can install this package and define the relevant environment variables so that packages know where to look for certificates. @xref{X.509 Certificates}, for detailed information. @subsection Emacs Packages @cindex @code{emacs} When you install Emacs packages with Guix, the Elisp files are placed under the @file{share/emacs/site-lisp/} directory of the profile in which they are installed. The Elisp libraries are made available to Emacs through the @env{EMACSLOADPATH} environment variable, which is set when installing Emacs itself. Additionally, autoload definitions are automatically evaluated at the initialization of Emacs, by the Guix-specific @code{guix-emacs-autoload-packages} procedure. If, for some reason, you want to avoid auto-loading the Emacs packages installed with Guix, you can do so by running Emacs with the @option{--no-site-file} option (@pxref{Init File,,, emacs, The GNU Emacs Manual}). @node Upgrading Guix @section Upgrading Guix @cindex Upgrading Guix, on a foreign distro To upgrade Guix, run: @example guix pull @end example @xref{Invoking guix pull}, for more information. @cindex upgrading Guix for the root user, on a foreign distro @cindex upgrading the Guix daemon, on a foreign distro @cindex @command{guix pull} for the root user, on a foreign distro On a foreign distro, you can upgrade the build daemon by running: @example sudo -i guix pull @end example @noindent followed by (assuming your distro uses the systemd service management tool): @example systemctl restart guix-daemon.service @end example On Guix System, upgrading the daemon is achieved by reconfiguring the system (@pxref{Invoking guix system, @code{guix system reconfigure}}). @c TODO What else? @c ********************************************************************* @node System Installation @chapter System Installation @cindex installing Guix System @cindex Guix System, installation This section explains how to install Guix System on a machine. Guix, as a package manager, can also be installed on top of a running GNU/Linux system, @pxref{Installation}. @ifinfo @quotation Note @c This paragraph is for people reading this from tty2 of the @c installation image. You are reading this documentation with an Info reader. For details on how to use it, hit the @key{RET} key (``return'' or ``enter'') on the link that follows: @pxref{Top, Info reader,, info-stnd, Stand-alone GNU Info}. Hit @kbd{l} afterwards to come back here. Alternatively, run @command{info info} in another tty to keep the manual available. @end quotation @end ifinfo @menu * Limitations:: What you can expect. * Hardware Considerations:: Supported hardware. * USB Stick and DVD Installation:: Preparing the installation medium. * Preparing for Installation:: Networking, partitioning, etc. * Guided Graphical Installation:: Easy graphical installation. * Manual Installation:: Manual installation for wizards. * After System Installation:: When installation succeeded. * Installing Guix in a VM:: Guix System playground. * Building the Installation Image:: How this comes to be. @end menu @node Limitations @section Limitations We consider Guix System to be ready for a wide range of ``desktop'' and server use cases. The reliability guarantees it provides---transactional upgrades and rollbacks, reproducibility---make it a solid foundation. Nevertheless, before you proceed with the installation, be aware of the following noteworthy limitations applicable to version @value{VERSION}: @itemize @item More and more system services are provided (@pxref{Services}), but some may be missing. @item GNOME, Xfce, LXDE, and Enlightenment are available (@pxref{Desktop Services}), as well as a number of X11 window managers. However, KDE is currently missing. @end itemize More than a disclaimer, this is an invitation to report issues (and success stories!), and to join us in improving it. @xref{Contributing}, for more info. @node Hardware Considerations @section Hardware Considerations @cindex hardware support on Guix System GNU@tie{}Guix focuses on respecting the user's computing freedom. It builds around the kernel Linux-libre, which means that only hardware for which free software drivers and firmware exist is supported. Nowadays, a wide range of off-the-shelf hardware is supported on GNU/Linux-libre---from keyboards to graphics cards to scanners and Ethernet controllers. Unfortunately, there are still areas where hardware vendors deny users control over their own computing, and such hardware is not supported on Guix System. @cindex WiFi, hardware support One of the main areas where free drivers or firmware are lacking is WiFi devices. WiFi devices known to work include those using Atheros chips (AR9271 and AR7010), which corresponds to the @code{ath9k} Linux-libre driver, and those using Broadcom/AirForce chips (BCM43xx with Wireless-Core Revision 5), which corresponds to the @code{b43-open} Linux-libre driver. Free firmware exists for both and is available out-of-the-box on Guix System, as part of @code{%base-firmware} (@pxref{operating-system Reference, @code{firmware}}). @cindex RYF, Respects Your Freedom The @uref{https://www.fsf.org/, Free Software Foundation} runs @uref{https://www.fsf.org/ryf, @dfn{Respects Your Freedom}} (RYF), a certification program for hardware products that respect your freedom and your privacy and ensure that you have control over your device. We encourage you to check the list of RYF-certified devices. Another useful resource is the @uref{https://www.h-node.org/, H-Node} web site. It contains a catalog of hardware devices with information about their support in GNU/Linux. @node USB Stick and DVD Installation @section USB Stick and DVD Installation An ISO-9660 installation image that can be written to a USB stick or burnt to a DVD can be downloaded from @indicateurl{@value{BASE-URL}/guix-system-install-@value{VERSION}.x86_64-linux.iso.xz}, where you can replace @code{x86_64-linux} with one of: @table @code @item x86_64-linux for a GNU/Linux system on Intel/AMD-compatible 64-bit CPUs; @item i686-linux for a 32-bit GNU/Linux system on Intel-compatible CPUs. @end table @c start duplication of authentication part from ``Binary Installation'' Make sure to download the associated @file{.sig} file and to verify the authenticity of the image against it, along these lines: @example $ wget @value{BASE-URL}/guix-system-install-@value{VERSION}.x86_64-linux.iso.xz.sig $ gpg --verify guix-system-install-@value{VERSION}.x86_64-linux.iso.xz.sig @end example If that command fails because you do not have the required public key, then run this command to import it: @example $ wget @value{OPENPGP-SIGNING-KEY-URL} \ -qO - | gpg --import - @end example @noindent and rerun the @code{gpg --verify} command. Take note that a warning like ``This key is not certified with a trusted signature!'' is normal. @c end duplication This image contains the tools necessary for an installation. It is meant to be copied @emph{as is} to a large-enough USB stick or DVD. @unnumberedsubsec Copying to a USB Stick To copy the image to a USB stick, follow these steps: @enumerate @item Decompress the image using the @command{xz} command: @example xz -d guix-system-install-@value{VERSION}.x86_64-linux.iso.xz @end example @item Insert a USB stick of 1@tie{}GiB or more into your machine, and determine its device name. Assuming that the USB stick is known as @file{/dev/sdX}, copy the image with: @example dd if=guix-system-install-@value{VERSION}.x86_64-linux.iso of=/dev/sdX status=progress sync @end example Access to @file{/dev/sdX} usually requires root privileges. @end enumerate @unnumberedsubsec Burning on a DVD To copy the image to a DVD, follow these steps: @enumerate @item Decompress the image using the @command{xz} command: @example xz -d guix-system-install-@value{VERSION}.x86_64-linux.iso.xz @end example @item Insert a blank DVD into your machine, and determine its device name. Assuming that the DVD drive is known as @file{/dev/srX}, copy the image with: @example growisofs -dvd-compat -Z /dev/srX=guix-system-install-@value{VERSION}.x86_64-linux.iso @end example Access to @file{/dev/srX} usually requires root privileges. @end enumerate @unnumberedsubsec Booting Once this is done, you should be able to reboot the system and boot from the USB stick or DVD. The latter usually requires you to get in the BIOS or UEFI boot menu, where you can choose to boot from the USB stick. In order to boot from Libreboot, switch to the command mode by pressing the @kbd{c} key and type @command{search_grub usb}. @xref{Installing Guix in a VM}, if, instead, you would like to install Guix System in a virtual machine (VM). @node Preparing for Installation @section Preparing for Installation Once you have booted, you can use the guided graphical installer, which makes it easy to get started (@pxref{Guided Graphical Installation}). Alternatively, if you are already familiar with GNU/Linux and if you want more control than what the graphical installer provides, you can choose the ``manual'' installation process (@pxref{Manual Installation}). The graphical installer is available on TTY1. You can obtain root shells on TTYs 3 to 6 by hitting @kbd{ctrl-alt-f3}, @kbd{ctrl-alt-f4}, etc. TTY2 shows this documentation and you can reach it with @kbd{ctrl-alt-f2}. Documentation is browsable using the Info reader commands (@pxref{Top,,, info-stnd, Stand-alone GNU Info}). The installation system runs the GPM mouse daemon, which allows you to select text with the left mouse button and to paste it with the middle button. @quotation Note Installation requires access to the Internet so that any missing dependencies of your system configuration can be downloaded. See the ``Networking'' section below. @end quotation @node Guided Graphical Installation @section Guided Graphical Installation The graphical installer is a text-based user interface. It will guide you, with dialog boxes, through the steps needed to install GNU@tie{}Guix System. The first dialog boxes allow you to set up the system as you use it during the installation: you can choose the language, keyboard layout, and set up networking, which will be used during the installation. The image below shows the networking dialog. @image{images/installer-network,5in,, networking setup with the graphical installer} Later steps allow you to partition your hard disk, as shown in the image below, to choose whether or not to use encrypted file systems, to enter the host name and root password, and to create an additional account, among other things. @image{images/installer-partitions,5in,, partitioning with the graphical installer} Note that, at any time, the installer allows you to exit the current installation step and resume at a previous step, as show in the image below. @image{images/installer-resume,5in,, resuming the installation process} Once you're done, the installer produces an operating system configuration and displays it (@pxref{Using the Configuration System}). At that point you can hit ``OK'' and installation will proceed. On success, you can reboot into the new system and enjoy. @xref{After System Installation}, for what's next! @node Manual Installation @section Manual Installation This section describes how you would ``manually'' install GNU@tie{}Guix System on your machine. This option requires familiarity with GNU/Linux, with the shell, and with common administration tools. If you think this is not for you, consider using the guided graphical installer (@pxref{Guided Graphical Installation}). The installation system provides root shells on TTYs 3 to 6; press @kbd{ctrl-alt-f3}, @kbd{ctrl-alt-f4}, and so on to reach them. It includes many common tools needed to install the system. But it is also a full-blown Guix System, which means that you can install additional packages, should you need it, using @command{guix package} (@pxref{Invoking guix package}). @menu * Keyboard Layout and Networking and Partitioning:: Initial setup. * Proceeding with the Installation:: Installing. @end menu @node Keyboard Layout and Networking and Partitioning @subsection Keyboard Layout, Networking, and Partitioning Before you can install the system, you may want to adjust the keyboard layout, set up networking, and partition your target hard disk. This section will guide you through this. @subsubsection Keyboard Layout @cindex keyboard layout The installation image uses the US qwerty keyboard layout. If you want to change it, you can use the @command{loadkeys} command. For example, the following command selects the Dvorak keyboard layout: @example loadkeys dvorak @end example See the files under @file{/run/current-system/profile/share/keymaps} for a list of available keyboard layouts. Run @command{man loadkeys} for more information. @subsubsection Networking Run the following command to see what your network interfaces are called: @example ifconfig -a @end example @noindent @dots{} or, using the GNU/Linux-specific @command{ip} command: @example ip address @end example @c https://cgit.freedesktop.org/systemd/systemd/tree/src/udev/udev-builtin-net_id.c#n20 Wired interfaces have a name starting with @samp{e}; for example, the interface corresponding to the first on-board Ethernet controller is called @samp{eno1}. Wireless interfaces have a name starting with @samp{w}, like @samp{w1p2s0}. @table @asis @item Wired connection To configure a wired network run the following command, substituting @var{interface} with the name of the wired interface you want to use. @example ifconfig @var{interface} up @end example @noindent @dots{} or, using the GNU/Linux-specific @command{ip} command: @example ip link set @var{interface} up @end example @item Wireless connection @cindex wireless @cindex WiFi To configure wireless networking, you can create a configuration file for the @command{wpa_supplicant} configuration tool (its location is not important) using one of the available text editors such as @command{nano}: @example nano wpa_supplicant.conf @end example As an example, the following stanza can go to this file and will work for many wireless networks, provided you give the actual SSID and passphrase for the network you are connecting to: @example network=@{ ssid="@var{my-ssid}" key_mgmt=WPA-PSK psk="the network's secret passphrase" @} @end example Start the wireless service and run it in the background with the following command (substitute @var{interface} with the name of the network interface you want to use): @example wpa_supplicant -c wpa_supplicant.conf -i @var{interface} -B @end example Run @command{man wpa_supplicant} for more information. @end table @cindex DHCP At this point, you need to acquire an IP address. On a network where IP addresses are automatically assigned @i{via} DHCP, you can run: @example dhclient -v @var{interface} @end example Try to ping a server to see if networking is up and running: @example ping -c 3 gnu.org @end example Setting up network access is almost always a requirement because the image does not contain all the software and tools that may be needed. @cindex proxy, during system installation If you need HTTP and HTTPS access to go through a proxy, run the following command: @example herd set-http-proxy guix-daemon @var{URL} @end example @noindent where @var{URL} is the proxy URL, for example @code{http://example.org:8118}. @cindex installing over SSH If you want to, you can continue the installation remotely by starting an SSH server: @example herd start ssh-daemon @end example Make sure to either set a password with @command{passwd}, or configure OpenSSH public key authentication before logging in. @subsubsection Disk Partitioning Unless this has already been done, the next step is to partition, and then format the target partition(s). The installation image includes several partitioning tools, including Parted (@pxref{Overview,,, parted, GNU Parted User Manual}), @command{fdisk}, and @command{cfdisk}. Run it and set up your disk with the partition layout you want: @example cfdisk @end example If your disk uses the GUID Partition Table (GPT) format and you plan to install BIOS-based GRUB (which is the default), make sure a BIOS Boot Partition is available (@pxref{BIOS installation,,, grub, GNU GRUB manual}). @cindex EFI, installation @cindex UEFI, installation @cindex ESP, EFI system partition If you instead wish to use EFI-based GRUB, a FAT32 @dfn{EFI System Partition} (ESP) is required. This partition can be mounted at @file{/boot/efi} for instance and must have the @code{esp} flag set. E.g., for @command{parted}: @example parted /dev/sda set 1 esp on @end example @quotation Note @vindex grub-bootloader @vindex grub-efi-bootloader Unsure whether to use EFI- or BIOS-based GRUB? If the directory @file{/sys/firmware/efi} exists in the installation image, then you should probably perform an EFI installation, using @code{grub-efi-bootloader}. Otherwise you should use the BIOS-based GRUB, known as @code{grub-bootloader}. @xref{Bootloader Configuration}, for more info on bootloaders. @end quotation Once you are done partitioning the target hard disk drive, you have to create a file system on the relevant partition(s)@footnote{Currently Guix System only supports ext4, btrfs, JFS, and F2FS file systems. In particular, code that reads file system UUIDs and labels only works for these file system types.}. For the ESP, if you have one and assuming it is @file{/dev/sda1}, run: @example mkfs.fat -F32 /dev/sda1 @end example For the root file system, ext4 is the most widely used format. Other file systems, such as Btrfs, support compression, which is reported to nicely complement file deduplication that the daemon performs independently of the file system (@pxref{Invoking guix-daemon, deduplication}). Preferably, assign file systems a label so that you can easily and reliably refer to them in @code{file-system} declarations (@pxref{File Systems}). This is typically done using the @code{-L} option of @command{mkfs.ext4} and related commands. So, assuming the target root partition lives at @file{/dev/sda2}, a file system with the label @code{my-root} can be created with: @example mkfs.ext4 -L my-root /dev/sda2 @end example @cindex encrypted disk If you are instead planning to encrypt the root partition, you can use the Cryptsetup/LUKS utilities to do that (see @inlinefmtifelse{html, @uref{https://linux.die.net/man/8/cryptsetup, @code{man cryptsetup}}, @code{man cryptsetup}} for more information). Assuming you want to store the root partition on @file{/dev/sda2}, the command sequence would be along these lines: @example cryptsetup luksFormat /dev/sda2 cryptsetup open --type luks /dev/sda2 my-partition mkfs.ext4 -L my-root /dev/mapper/my-partition @end example Once that is done, mount the target file system under @file{/mnt} with a command like (again, assuming @code{my-root} is the label of the root file system): @example mount LABEL=my-root /mnt @end example Also mount any other file systems you would like to use on the target system relative to this path. If you have opted for @file{/boot/efi} as an EFI mount point for example, mount it at @file{/mnt/boot/efi} now so it is found by @code{guix system init} afterwards. Finally, if you plan to use one or more swap partitions (@pxref{Memory Concepts, swap space,, libc, The GNU C Library Reference Manual}), make sure to initialize them with @command{mkswap}. Assuming you have one swap partition on @file{/dev/sda3}, you would run: @example mkswap /dev/sda3 swapon /dev/sda3 @end example Alternatively, you may use a swap file. For example, assuming that in the new system you want to use the file @file{/swapfile} as a swap file, you would run@footnote{This example will work for many types of file systems (e.g., ext4). However, for copy-on-write file systems (e.g., btrfs), the required steps may be different. For details, see the manual pages for @command{mkswap} and @command{swapon}.}: @example # This is 10 GiB of swap space. Adjust "count" to change the size. dd if=/dev/zero of=/mnt/swapfile bs=1MiB count=10240 # For security, make the file readable and writable only by root. chmod 600 /mnt/swapfile mkswap /mnt/swapfile swapon /mnt/swapfile @end example Note that if you have encrypted the root partition and created a swap file in its file system as described above, then the encryption also protects the swap file, just like any other file in that file system. @node Proceeding with the Installation @subsection Proceeding with the Installation With the target partitions ready and the target root mounted on @file{/mnt}, we're ready to go. First, run: @example herd start cow-store /mnt @end example This makes @file{/gnu/store} copy-on-write, such that packages added to it during the installation phase are written to the target disk on @file{/mnt} rather than kept in memory. This is necessary because the first phase of the @command{guix system init} command (see below) entails downloads or builds to @file{/gnu/store} which, initially, is an in-memory file system. Next, you have to edit a file and provide the declaration of the operating system to be installed. To that end, the installation system comes with three text editors. We recommend GNU nano (@pxref{Top,,, nano, GNU nano Manual}), which supports syntax highlighting and parentheses matching; other editors include GNU Zile (an Emacs clone), and nvi (a clone of the original BSD @command{vi} editor). We strongly recommend storing that file on the target root file system, say, as @file{/mnt/etc/config.scm}. Failing to do that, you will have lost your configuration file once you have rebooted into the newly-installed system. @xref{Using the Configuration System}, for an overview of the configuration file. The example configurations discussed in that section are available under @file{/etc/configuration} in the installation image. Thus, to get started with a system configuration providing a graphical display server (a ``desktop'' system), you can run something along these lines: @example # mkdir /mnt/etc # cp /etc/configuration/desktop.scm /mnt/etc/config.scm # nano /mnt/etc/config.scm @end example You should pay attention to what your configuration file contains, and in particular: @itemize @item Make sure the @code{bootloader-configuration} form refers to the target you want to install GRUB on. It should mention @code{grub-bootloader} if you are installing GRUB in the legacy way, or @code{grub-efi-bootloader} for newer UEFI systems. For legacy systems, the @code{target} field names a device, like @code{/dev/sda}; for UEFI systems it names a path to a mounted EFI partition, like @code{/boot/efi}; do make sure the path is currently mounted and a @code{file-system} entry is specified in your configuration. @item Be sure that your file system labels match the value of their respective @code{device} fields in your @code{file-system} configuration, assuming your @code{file-system} configuration uses the @code{file-system-label} procedure in its @code{device} field. @item If there are encrypted or RAID partitions, make sure to add a @code{mapped-devices} field to describe them (@pxref{Mapped Devices}). @end itemize Once you are done preparing the configuration file, the new system must be initialized (remember that the target root file system is mounted under @file{/mnt}): @example guix system init /mnt/etc/config.scm /mnt @end example @noindent This copies all the necessary files and installs GRUB on @file{/dev/sdX}, unless you pass the @option{--no-bootloader} option. For more information, @pxref{Invoking guix system}. This command may trigger downloads or builds of missing packages, which can take some time. Once that command has completed---and hopefully succeeded!---you can run @command{reboot} and boot into the new system. The @code{root} password in the new system is initially empty; other users' passwords need to be initialized by running the @command{passwd} command as @code{root}, unless your configuration specifies otherwise (@pxref{user-account-password, user account passwords}). @xref{After System Installation}, for what's next! @node After System Installation @section After System Installation Success, you've now booted into Guix System! From then on, you can update the system whenever you want by running, say: @example guix pull sudo guix system reconfigure /etc/config.scm @end example @noindent This builds a new system generation with the latest packages and services (@pxref{Invoking guix system}). We recommend doing that regularly so that your system includes the latest security updates (@pxref{Security Updates}). @c See . @quotation Note @cindex sudo vs. @command{guix pull} Note that @command{sudo guix} runs your user's @command{guix} command and @emph{not} root's, because @command{sudo} leaves @env{PATH} unchanged. To explicitly run root's @command{guix}, type @command{sudo -i guix @dots{}}. The difference matters here, because @command{guix pull} updates the @command{guix} command and package definitions only for the user it is ran as. This means that if you choose to use @command{guix system reconfigure} in root's login shell, you'll need to @command{guix pull} separately. @end quotation Now, @pxref{Getting Started}, and join us on @code{#guix} on the Freenode IRC network or on @email{guix-devel@@gnu.org} to share your experience! @node Installing Guix in a VM @section Installing Guix in a Virtual Machine @cindex virtual machine, Guix System installation @cindex virtual private server (VPS) @cindex VPS (virtual private server) If you'd like to install Guix System in a virtual machine (VM) or on a virtual private server (VPS) rather than on your beloved machine, this section is for you. To boot a @uref{https://qemu.org/,QEMU} VM for installing Guix System in a disk image, follow these steps: @enumerate @item First, retrieve and decompress the Guix system installation image as described previously (@pxref{USB Stick and DVD Installation}). @item Create a disk image that will hold the installed system. To make a qcow2-formatted disk image, use the @command{qemu-img} command: @example qemu-img create -f qcow2 guix-system.img 50G @end example The resulting file will be much smaller than 50 GB (typically less than 1 MB), but it will grow as the virtualized storage device is filled up. @item Boot the USB installation image in an VM: @example qemu-system-x86_64 -m 1024 -smp 1 -enable-kvm \ -nic user,model=virtio-net-pci -boot menu=on,order=d \ -drive file=guix-system.img \ -drive media=cdrom,file=guix-system-install-@value{VERSION}.@var{system}.iso @end example @code{-enable-kvm} is optional, but significantly improves performance, @pxref{Running Guix in a VM}. @item You're now root in the VM, proceed with the installation process. @xref{Preparing for Installation}, and follow the instructions. @end enumerate Once installation is complete, you can boot the system that's on your @file{guix-system.img} image. @xref{Running Guix in a VM}, for how to do that. @node Building the Installation Image @section Building the Installation Image @cindex installation image The installation image described above was built using the @command{guix system} command, specifically: @example guix system disk-image -t iso9660 gnu/system/install.scm @end example Have a look at @file{gnu/system/install.scm} in the source tree, and see also @ref{Invoking guix system} for more information about the installation image. @section Building the Installation Image for ARM Boards Many ARM boards require a specific variant of the @uref{https://www.denx.de/wiki/U-Boot/, U-Boot} bootloader. If you build a disk image and the bootloader is not available otherwise (on another boot drive etc), it's advisable to build an image that includes the bootloader, specifically: @example guix system disk-image --system=armhf-linux -e '((@@ (gnu system install) os-with-u-boot) (@@ (gnu system install) installation-os) "A20-OLinuXino-Lime2")' @end example @code{A20-OLinuXino-Lime2} is the name of the board. If you specify an invalid board, a list of possible boards will be printed. @c ********************************************************************* @node Getting Started @chapter Getting Started Presumably, you've reached this section because either you have installed Guix on top of another distribution (@pxref{Installation}), or you've installed the standalone Guix System (@pxref{System Installation}). It's time for you to get started using Guix and this section aims to help you do that and give you a feel of what it's like. Guix is about installing software, so probably the first thing you'll want to do is to actually look for software. Let's say you're looking for a text editor, you can run: @example guix search text editor @end example This command shows you a number of matching @dfn{packages}, each time showing the package's name, version, a description, and additional info. Once you've found out the one you want to use, let's say Emacs (ah ha!), you can go ahead and install it (run this command as a regular user, @emph{no need for root privileges}!): @example guix install emacs @end example You've installed your first package, congrats! In the process, you've probably noticed that Guix downloaded pre-built binaries; or, if you explicitly chose to @emph{not} use pre-built binaries, then probably Guix is still building software (@pxref{Substitutes}, for more info). Unless you're using Guix System, the @command{guix install} command must have printed this hint: @example hint: Consider setting the necessary environment variables by running: GUIX_PROFILE="$HOME/.guix-profile" . "$GUIX_PROFILE/etc/profile" Alternately, see `guix package --search-paths -p "$HOME/.guix-profile"'. @end example Indeed, you must now tell your shell where @command{emacs} and other programs installed with Guix are to be found. Pasting the two lines above will do just that: it will add @code{$HOME/.guix-profile/bin}---which is where the installed package is---to the @code{PATH} environment variable. You can paste these two lines in your shell so they take effect right away, but more importantly you should add them to @file{~/.bash_profile} (or equivalent file if you do not use Bash) so that environment variables are set next time you spawn a shell. You only need to do this once and other search paths environment variables will be taken care of similarly---e.g., if you eventually install @code{python} and Python libraries, @code{PYTHONPATH} will be defined. You can go on installing packages at your will. To list installed packages, run: @example guix package --list-installed @end example To remove a package, you would unsurprisingly run @command{guix remove}. A distinguishing feature is the ability to @dfn{roll back} any operation you made---installation, removal, upgrade---by simply typing: @example guix package --roll-back @end example This is because each operation is in fact a @dfn{transaction} that creates a new @dfn{generation}. These generations and the difference between them can be displayed by running: @example guix package --list-generations @end example Now you know the basics of package management! @quotation Going further @xref{Package Management}, for more about package management. You may like @dfn{declarative} package management with @command{guix package --manifest}, managing separate @dfn{profiles} with @option{--profile}, deleting old generations, collecting garbage, and other nifty features that will come in handy as you become more familiar with Guix. If you are a developer, @pxref{Development} for additional tools. And if you're curious, @pxref{Features}, to peek under the hood. @end quotation Once you've installed a set of packages, you will want to periodically @emph{upgrade} them to the latest and greatest version. To do that, you will first pull the latest revision of Guix and its package collection: @example guix pull @end example The end result is a new @command{guix} command, under @file{~/.config/guix/current/bin}. Unless you're on Guix System, the first time you run @command{guix pull}, be sure to follow the hint that the command prints and, similar to what we saw above, paste these two lines in your terminal and @file{.bash_profile}: @example GUIX_PROFILE="$HOME/.config/guix/current" . "$GUIX_PROFILE/etc/profile" @end example @noindent You must also instruct your shell to point to this new @command{guix}: @example hash guix @end example At this point, you're running a brand new Guix. You can thus go ahead and actually upgrade all the packages you previously installed: @example guix upgrade @end example As you run this command, you will see that binaries are downloaded (or perhaps some packages are built), and eventually you end up with the upgraded packages. Should one of these upgraded packages not be to your liking, remember you can always roll back! You can display the exact revision of Guix you're currently using by running: @example guix describe @end example The information it displays is @emph{all it takes to reproduce the exact same Guix}, be it at a different point in time or on a different machine. @quotation Going further @xref{Invoking guix pull}, for more information. @xref{Channels}, on how to specify additional @dfn{channels} to pull packages from, how to replicate Guix, and more. You may also find @command{time-machine} handy (@pxref{Invoking guix time-machine}). @end quotation If you installed Guix System, one of the first things you'll want to do is to upgrade your system. Once you've run @command{guix pull} to get the latest Guix, you can upgrade the system like this: @example sudo guix system reconfigure /etc/config.scm @end example Upon completion, the system runs the latest versions of its software packages. When you eventually reboot, you'll notice a sub-menu in the bootloader that reads ``Old system generations'': it's what allows you to boot @emph{an older generation of your system}, should the latest generation be ``broken'' or otherwise unsatisfying. Just like for packages, you can always @emph{roll back} to a previous generation @emph{of the whole system}: @example sudo guix system roll-back @end example There are many things you'll probably want to tweak on your system: adding new user accounts, adding new system services, fiddling with the configuration of those services, etc. The system configuration is @emph{entirely} described in the @file{/etc/config.scm} file. @xref{Using the Configuration System}, to learn how to change it. Now you know enough to get started! @quotation Resources The rest of this manual provides a reference for all things Guix. Here are some additional resources you may find useful: @itemize @item @xref{Top,,, guix-cookbook, The GNU Guix Cookbook}, for a list of ``how-to'' style of recipes for a variety of applications. @item The @uref{https://guix.gnu.org/guix-refcard.pdf, GNU Guix Reference Card} lists in two pages most of the commands and options you'll ever need. @item The web site contains @uref{https://guix.gnu.org/en/videos/, instructional videos} covering topics such as everyday use of Guix, how to get help, and how to become a contributor. @item @xref{Documentation}, to learn how to access documentation on your computer. @end itemize We hope you will enjoy Guix as much as the community enjoys building it! @end quotation @c ********************************************************************* @node Package Management @chapter Package Management @cindex packages The purpose of GNU Guix is to allow users to easily install, upgrade, and remove software packages, without having to know about their build procedures or dependencies. Guix also goes beyond this obvious set of features. This chapter describes the main features of Guix, as well as the package management tools it provides. Along with the command-line interface described below (@pxref{Invoking guix package, @code{guix package}}), you may also use the Emacs-Guix interface (@pxref{Top,,, emacs-guix, The Emacs-Guix Reference Manual}), after installing @code{emacs-guix} package (run @kbd{M-x guix-help} command to start with it): @example guix install emacs-guix @end example @menu * Features:: How Guix will make your life brighter. * Invoking guix package:: Package installation, removal, etc. * Substitutes:: Downloading pre-built binaries. * Packages with Multiple Outputs:: Single source package, multiple outputs. * Invoking guix gc:: Running the garbage collector. * Invoking guix pull:: Fetching the latest Guix and distribution. * Invoking guix time-machine:: Running an older revision of Guix. * Inferiors:: Interacting with another revision of Guix. * Invoking guix describe:: Display information about your Guix revision. * Invoking guix archive:: Exporting and importing store files. @end menu @node Features @section Features Here we assume you've already made your first steps with Guix (@pxref{Getting Started}) and would like to get an overview about what's going on under the hood. When using Guix, each package ends up in the @dfn{package store}, in its own directory---something that resembles @file{/gnu/store/xxx-package-1.2}, where @code{xxx} is a base32 string. Instead of referring to these directories, users have their own @dfn{profile}, which points to the packages that they actually want to use. These profiles are stored within each user's home directory, at @code{$HOME/.guix-profile}. For example, @code{alice} installs GCC 4.7.2. As a result, @file{/home/alice/.guix-profile/bin/gcc} points to @file{/gnu/store/@dots{}-gcc-4.7.2/bin/gcc}. Now, on the same machine, @code{bob} had already installed GCC 4.8.0. The profile of @code{bob} simply continues to point to @file{/gnu/store/@dots{}-gcc-4.8.0/bin/gcc}---i.e., both versions of GCC coexist on the same system without any interference. The @command{guix package} command is the central tool to manage packages (@pxref{Invoking guix package}). It operates on the per-user profiles, and can be used @emph{with normal user privileges}. @cindex transactions The command provides the obvious install, remove, and upgrade operations. Each invocation is actually a @emph{transaction}: either the specified operation succeeds, or nothing happens. Thus, if the @command{guix package} process is terminated during the transaction, or if a power outage occurs during the transaction, then the user's profile remains in its previous state, and remains usable. In addition, any package transaction may be @emph{rolled back}. So, if, for example, an upgrade installs a new version of a package that turns out to have a serious bug, users may roll back to the previous instance of their profile, which was known to work well. Similarly, the global system configuration on Guix is subject to transactional upgrades and roll-back (@pxref{Using the Configuration System}). All packages in the package store may be @emph{garbage-collected}. Guix can determine which packages are still referenced by user profiles, and remove those that are provably no longer referenced (@pxref{Invoking guix gc}). Users may also explicitly remove old generations of their profile so that the packages they refer to can be collected. @cindex reproducibility @cindex reproducible builds Guix takes a @dfn{purely functional} approach to package management, as described in the introduction (@pxref{Introduction}). Each @file{/gnu/store} package directory name contains a hash of all the inputs that were used to build that package---compiler, libraries, build scripts, etc. This direct correspondence allows users to make sure a given package installation matches the current state of their distribution. It also helps maximize @dfn{build reproducibility}: thanks to the isolated build environments that are used, a given build is likely to yield bit-identical files when performed on different machines (@pxref{Invoking guix-daemon, container}). @cindex substitutes This foundation allows Guix to support @dfn{transparent binary/source deployment}. When a pre-built binary for a @file{/gnu/store} item is available from an external source---a @dfn{substitute}, Guix just downloads it and unpacks it; otherwise, it builds the package from source, locally (@pxref{Substitutes}). Because build results are usually bit-for-bit reproducible, users do not have to trust servers that provide substitutes: they can force a local build and @emph{challenge} providers (@pxref{Invoking guix challenge}). Control over the build environment is a feature that is also useful for developers. The @command{guix environment} command allows developers of a package to quickly set up the right development environment for their package, without having to manually install the dependencies of the package into their profile (@pxref{Invoking guix environment}). @cindex replication, of software environments @cindex provenance tracking, of software artifacts All of Guix and its package definitions is version-controlled, and @command{guix pull} allows you to ``travel in time'' on the history of Guix itself (@pxref{Invoking guix pull}). This makes it possible to replicate a Guix instance on a different machine or at a later point in time, which in turn allows you to @emph{replicate complete software environments}, while retaining precise @dfn{provenance tracking} of the software. @node Invoking guix package @section Invoking @command{guix package} @cindex installing packages @cindex removing packages @cindex package installation @cindex package removal The @command{guix package} command is the tool that allows users to install, upgrade, and remove packages, as well as rolling back to previous configurations. It operates only on the user's own profile, and works with normal user privileges (@pxref{Features}). Its syntax is: @example guix package @var{options} @end example @cindex transactions Primarily, @var{options} specifies the operations to be performed during the transaction. Upon completion, a new profile is created, but previous @dfn{generations} of the profile remain available, should the user want to roll back. For example, to remove @code{lua} and install @code{guile} and @code{guile-cairo} in a single transaction: @example guix package -r lua -i guile guile-cairo @end example @cindex aliases, for @command{guix package} For your convenience, we also provide the following aliases: @itemize @item @command{guix search} is an alias for @command{guix package -s}, @item @command{guix install} is an alias for @command{guix package -i}, @item @command{guix remove} is an alias for @command{guix package -r}, @item @command{guix upgrade} is an alias for @command{guix package -u}, @item and @command{guix show} is an alias for @command{guix package --show=}. @end itemize These aliases are less expressive than @command{guix package} and provide fewer options, so in some cases you'll probably want to use @command{guix package} directly. @command{guix package} also supports a @dfn{declarative approach} whereby the user specifies the exact set of packages to be available and passes it @i{via} the @option{--manifest} option (@pxref{profile-manifest, @option{--manifest}}). @cindex profile For each user, a symlink to the user's default profile is automatically created in @file{$HOME/.guix-profile}. This symlink always points to the current generation of the user's default profile. Thus, users can add @file{$HOME/.guix-profile/bin} to their @env{PATH} environment variable, and so on. @cindex search paths If you are not using Guix System, consider adding the following lines to your @file{~/.bash_profile} (@pxref{Bash Startup Files,,, bash, The GNU Bash Reference Manual}) so that newly-spawned shells get all the right environment variable definitions: @example GUIX_PROFILE="$HOME/.guix-profile" ; \ source "$HOME/.guix-profile/etc/profile" @end example In a multi-user setup, user profiles are stored in a place registered as a @dfn{garbage-collector root}, which @file{$HOME/.guix-profile} points to (@pxref{Invoking guix gc}). That directory is normally @code{@var{localstatedir}/guix/profiles/per-user/@var{user}}, where @var{localstatedir} is the value passed to @code{configure} as @option{--localstatedir}, and @var{user} is the user name. The @file{per-user} directory is created when @command{guix-daemon} is started, and the @var{user} sub-directory is created by @command{guix package}. The @var{options} can be among the following: @table @code @item --install=@var{package} @dots{} @itemx -i @var{package} @dots{} Install the specified @var{package}s. Each @var{package} may specify either a simple package name, such as @code{guile}, or a package name followed by an at-sign and version number, such as @code{guile@@1.8.8} or simply @code{guile@@1.8} (in the latter case, the newest version prefixed by @code{1.8} is selected). If no version number is specified, the newest available version will be selected. In addition, @var{package} may contain a colon, followed by the name of one of the outputs of the package, as in @code{gcc:doc} or @code{binutils@@2.22:lib} (@pxref{Packages with Multiple Outputs}). Packages with a corresponding name (and optionally version) are searched for among the GNU distribution modules (@pxref{Package Modules}). @cindex propagated inputs Sometimes packages have @dfn{propagated inputs}: these are dependencies that automatically get installed along with the required package (@pxref{package-propagated-inputs, @code{propagated-inputs} in @code{package} objects}, for information about propagated inputs in package definitions). @anchor{package-cmd-propagated-inputs} An example is the GNU MPC library: its C header files refer to those of the GNU MPFR library, which in turn refer to those of the GMP library. Thus, when installing MPC, the MPFR and GMP libraries also get installed in the profile; removing MPC also removes MPFR and GMP---unless they had also been explicitly installed by the user. Besides, packages sometimes rely on the definition of environment variables for their search paths (see explanation of @option{--search-paths} below). Any missing or possibly incorrect environment variable definitions are reported here. @item --install-from-expression=@var{exp} @itemx -e @var{exp} Install the package @var{exp} evaluates to. @var{exp} must be a Scheme expression that evaluates to a @code{} object. This option is notably useful to disambiguate between same-named variants of a package, with expressions such as @code{(@@ (gnu packages base) guile-final)}. Note that this option installs the first output of the specified package, which may be insufficient when needing a specific output of a multiple-output package. @item --install-from-file=@var{file} @itemx -f @var{file} Install the package that the code within @var{file} evaluates to. As an example, @var{file} might contain a definition like this (@pxref{Defining Packages}): @lisp @include package-hello.scm @end lisp Developers may find it useful to include such a @file{guix.scm} file in the root of their project source tree that can be used to test development snapshots and create reproducible development environments (@pxref{Invoking guix environment}). The @var{file} may also contain a JSON representation of one or more package definitions. Running @code{guix package -f} on @file{hello.json} with the following contents would result in installing the package @code{greeter} after building @code{myhello}: @example @verbatiminclude package-hello.json @end example @item --remove=@var{package} @dots{} @itemx -r @var{package} @dots{} Remove the specified @var{package}s. As for @option{--install}, each @var{package} may specify a version number and/or output name in addition to the package name. For instance, @samp{-r glibc:debug} would remove the @code{debug} output of @code{glibc}. @item --upgrade[=@var{regexp} @dots{}] @itemx -u [@var{regexp} @dots{}] @cindex upgrading packages Upgrade all the installed packages. If one or more @var{regexp}s are specified, upgrade only installed packages whose name matches a @var{regexp}. Also see the @option{--do-not-upgrade} option below. Note that this upgrades package to the latest version of packages found in the distribution currently installed. To update your distribution, you should regularly run @command{guix pull} (@pxref{Invoking guix pull}). @cindex package transformations, upgrades When upgrading, package transformations that were originally applied when creating the profile are automatically re-applied (@pxref{Package Transformation Options}). For example, assume you first installed Emacs from the tip of its development branch with: @example guix install emacs-next --with-branch=emacs-next=master @end example Next time you run @command{guix upgrade}, Guix will again pull the tip of the Emacs development branch and build @code{emacs-next} from that checkout. Note that transformation options such as @option{--with-branch} and @option{--with-source} depend on external state; it is up to you to ensure that they work as expected. You can also discard a transformations that apply to a package by running: @example guix install @var{package} @end example @item --do-not-upgrade[=@var{regexp} @dots{}] When used together with the @option{--upgrade} option, do @emph{not} upgrade any packages whose name matches a @var{regexp}. For example, to upgrade all packages in the current profile except those containing the substring ``emacs'': @example $ guix package --upgrade . --do-not-upgrade emacs @end example @item @anchor{profile-manifest}--manifest=@var{file} @itemx -m @var{file} @cindex profile declaration @cindex profile manifest Create a new generation of the profile from the manifest object returned by the Scheme code in @var{file}. This option can be repeated several times, in which case the manifests are concatenated. This allows you to @emph{declare} the profile's contents rather than constructing it through a sequence of @option{--install} and similar commands. The advantage is that @var{file} can be put under version control, copied to different machines to reproduce the same profile, and so on. @c FIXME: Add reference to (guix profile) documentation when available. @var{file} must return a @dfn{manifest} object, which is roughly a list of packages: @findex packages->manifest @lisp (use-package-modules guile emacs) (packages->manifest (list emacs guile-2.0 ;; Use a specific package output. (list guile-2.0 "debug"))) @end lisp @findex specifications->manifest In this example we have to know which modules define the @code{emacs} and @code{guile-2.0} variables to provide the right @code{use-package-modules} line, which can be cumbersome. We can instead provide regular package specifications and let @code{specifications->manifest} look up the corresponding package objects, like this: @lisp (specifications->manifest '("emacs" "guile@@2.2" "guile@@2.2:debug")) @end lisp @item --roll-back @cindex rolling back @cindex undoing transactions @cindex transactions, undoing Roll back to the previous @dfn{generation} of the profile---i.e., undo the last transaction. When combined with options such as @option{--install}, roll back occurs before any other actions. When rolling back from the first generation that actually contains installed packages, the profile is made to point to the @dfn{zeroth generation}, which contains no files apart from its own metadata. After having rolled back, installing, removing, or upgrading packages overwrites previous future generations. Thus, the history of the generations in a profile is always linear. @item --switch-generation=@var{pattern} @itemx -S @var{pattern} @cindex generations Switch to a particular generation defined by @var{pattern}. @var{pattern} may be either a generation number or a number prefixed with ``+'' or ``-''. The latter means: move forward/backward by a specified number of generations. For example, if you want to return to the latest generation after @option{--roll-back}, use @option{--switch-generation=+1}. The difference between @option{--roll-back} and @option{--switch-generation=-1} is that @option{--switch-generation} will not make a zeroth generation, so if a specified generation does not exist, the current generation will not be changed. @item --search-paths[=@var{kind}] @cindex search paths Report environment variable definitions, in Bash syntax, that may be needed in order to use the set of installed packages. These environment variables are used to specify @dfn{search paths} for files used by some of the installed packages. For example, GCC needs the @env{CPATH} and @env{LIBRARY_PATH} environment variables to be defined so it can look for headers and libraries in the user's profile (@pxref{Environment Variables,,, gcc, Using the GNU Compiler Collection (GCC)}). If GCC and, say, the C library are installed in the profile, then @option{--search-paths} will suggest setting these variables to @file{@var{profile}/include} and @file{@var{profile}/lib}, respectively. The typical use case is to define these environment variables in the shell: @example $ eval `guix package --search-paths` @end example @var{kind} may be one of @code{exact}, @code{prefix}, or @code{suffix}, meaning that the returned environment variable definitions will either be exact settings, or prefixes or suffixes of the current value of these variables. When omitted, @var{kind} defaults to @code{exact}. This option can also be used to compute the @emph{combined} search paths of several profiles. Consider this example: @example $ guix package -p foo -i guile $ guix package -p bar -i guile-json $ guix package -p foo -p bar --search-paths @end example The last command above reports about the @env{GUILE_LOAD_PATH} variable, even though, taken individually, neither @file{foo} nor @file{bar} would lead to that recommendation. @item --profile=@var{profile} @itemx -p @var{profile} Use @var{profile} instead of the user's default profile. @var{profile} must be the name of a file that will be created upon completion. Concretely, @var{profile} will be a mere symbolic link (``symlink'') pointing to the actual profile where packages are installed: @example $ guix install hello -p ~/code/my-profile @dots{} $ ~/code/my-profile/bin/hello Hello, world! @end example All it takes to get rid of the profile is to remove this symlink and its siblings that point to specific generations: @example $ rm ~/code/my-profile ~/code/my-profile-*-link @end example @item --list-profiles List all the user's profiles: @example $ guix package --list-profiles /home/charlie/.guix-profile /home/charlie/code/my-profile /home/charlie/code/devel-profile /home/charlie/tmp/test @end example When running as root, list all the profiles of all the users. @cindex collisions, in a profile @cindex colliding packages in profiles @cindex profile collisions @item --allow-collisions Allow colliding packages in the new profile. Use at your own risk! By default, @command{guix package} reports as an error @dfn{collisions} in the profile. Collisions happen when two or more different versions or variants of a given package end up in the profile. @item --bootstrap Use the bootstrap Guile to build the profile. This option is only useful to distribution developers. @end table In addition to these actions, @command{guix package} supports the following options to query the current state of a profile, or the availability of packages: @table @option @item --search=@var{regexp} @itemx -s @var{regexp} @anchor{guix-search} @cindex searching for packages List the available packages whose name, synopsis, or description matches @var{regexp} (in a case-insensitive fashion), sorted by relevance. Print all the metadata of matching packages in @code{recutils} format (@pxref{Top, GNU recutils databases,, recutils, GNU recutils manual}). This allows specific fields to be extracted using the @command{recsel} command, for instance: @example $ guix package -s malloc | recsel -p name,version,relevance name: jemalloc version: 4.5.0 relevance: 6 name: glibc version: 2.25 relevance: 1 name: libgc version: 7.6.0 relevance: 1 @end example Similarly, to show the name of all the packages available under the terms of the GNU@tie{}LGPL version 3: @example $ guix package -s "" | recsel -p name -e 'license ~ "LGPL 3"' name: elfutils name: gmp @dots{} @end example It is also possible to refine search results using several @code{-s} flags to @command{guix package}, or several arguments to @command{guix search}. For example, the following command returns a list of board games (this time using the @command{guix search} alias): @example $ guix search '\' game | recsel -p name name: gnubg @dots{} @end example If we were to omit @code{-s game}, we would also get software packages that deal with printed circuit boards; removing the angle brackets around @code{board} would further add packages that have to do with keyboards. And now for a more elaborate example. The following command searches for cryptographic libraries, filters out Haskell, Perl, Python, and Ruby libraries, and prints the name and synopsis of the matching packages: @example $ guix search crypto library | \ recsel -e '! (name ~ "^(ghc|perl|python|ruby)")' -p name,synopsis @end example @noindent @xref{Selection Expressions,,, recutils, GNU recutils manual}, for more information on @dfn{selection expressions} for @code{recsel -e}. @item --show=@var{package} Show details about @var{package}, taken from the list of available packages, in @code{recutils} format (@pxref{Top, GNU recutils databases,, recutils, GNU recutils manual}). @example $ guix package --show=python | recsel -p name,version name: python version: 2.7.6 name: python version: 3.3.5 @end example You may also specify the full name of a package to only get details about a specific version of it (this time using the @command{guix show} alias): @example $ guix show python@@3.4 | recsel -p name,version name: python version: 3.4.3 @end example @item --list-installed[=@var{regexp}] @itemx -I [@var{regexp}] List the currently installed packages in the specified profile, with the most recently installed packages shown last. When @var{regexp} is specified, list only installed packages whose name matches @var{regexp}. For each installed package, print the following items, separated by tabs: the package name, its version string, the part of the package that is installed (for instance, @code{out} for the default output, @code{include} for its headers, etc.), and the path of this package in the store. @item --list-available[=@var{regexp}] @itemx -A [@var{regexp}] List packages currently available in the distribution for this system (@pxref{GNU Distribution}). When @var{regexp} is specified, list only available packages whose name matches @var{regexp}. For each package, print the following items separated by tabs: its name, its version string, the parts of the package (@pxref{Packages with Multiple Outputs}), and the source location of its definition. @item --list-generations[=@var{pattern}] @itemx -l [@var{pattern}] @cindex generations Return a list of generations along with their creation dates; for each generation, show the installed packages, with the most recently installed packages shown last. Note that the zeroth generation is never shown. For each installed package, print the following items, separated by tabs: the name of a package, its version string, the part of the package that is installed (@pxref{Packages with Multiple Outputs}), and the location of this package in the store. When @var{pattern} is used, the command returns only matching generations. Valid patterns include: @itemize @item @emph{Integers and comma-separated integers}. Both patterns denote generation numbers. For instance, @option{--list-generations=1} returns the first one. And @option{--list-generations=1,8,2} outputs three generations in the specified order. Neither spaces nor trailing commas are allowed. @item @emph{Ranges}. @option{--list-generations=2..9} prints the specified generations and everything in between. Note that the start of a range must be smaller than its end. It is also possible to omit the endpoint. For example, @option{--list-generations=2..}, returns all generations starting from the second one. @item @emph{Durations}. You can also get the last @emph{N}@tie{}days, weeks, or months by passing an integer along with the first letter of the duration. For example, @option{--list-generations=20d} lists generations that are up to 20 days old. @end itemize @item --delete-generations[=@var{pattern}] @itemx -d [@var{pattern}] When @var{pattern} is omitted, delete all generations except the current one. This command accepts the same patterns as @option{--list-generations}. When @var{pattern} is specified, delete the matching generations. When @var{pattern} specifies a duration, generations @emph{older} than the specified duration match. For instance, @option{--delete-generations=1m} deletes generations that are more than one month old. If the current generation matches, it is @emph{not} deleted. Also, the zeroth generation is never deleted. Note that deleting generations prevents rolling back to them. Consequently, this command must be used with care. @end table Finally, since @command{guix package} may actually start build processes, it supports all the common build options (@pxref{Common Build Options}). It also supports package transformation options, such as @option{--with-source} (@pxref{Package Transformation Options}). However, note that package transformations are lost when upgrading; to preserve transformations across upgrades, you should define your own package variant in a Guile module and add it to @env{GUIX_PACKAGE_PATH} (@pxref{Defining Packages}). @node Substitutes @section Substitutes @cindex substitutes @cindex pre-built binaries Guix supports transparent source/binary deployment, which means that it can either build things locally, or download pre-built items from a server, or both. We call these pre-built items @dfn{substitutes}---they are substitutes for local build results. In many cases, downloading a substitute is much faster than building things locally. Substitutes can be anything resulting from a derivation build (@pxref{Derivations}). Of course, in the common case, they are pre-built package binaries, but source tarballs, for instance, which also result from derivation builds, can be available as substitutes. @menu * Official Substitute Server:: One particular source of substitutes. * Substitute Server Authorization:: How to enable or disable substitutes. * Getting Substitutes from Other Servers:: Substitute diversity. * Substitute Authentication:: How Guix verifies substitutes. * Proxy Settings:: How to get substitutes via proxy. * Substitution Failure:: What happens when substitution fails. * On Trusting Binaries:: How can you trust that binary blob? @end menu @node Official Substitute Server @subsection Official Substitute Server @cindex build farm The @code{@value{SUBSTITUTE-SERVER}} server is a front-end to an official build farm that builds packages from Guix continuously for some architectures, and makes them available as substitutes. This is the default source of substitutes; it can be overridden by passing the @option{--substitute-urls} option either to @command{guix-daemon} (@pxref{daemon-substitute-urls,, @code{guix-daemon --substitute-urls}}) or to client tools such as @command{guix package} (@pxref{client-substitute-urls,, client @option{--substitute-urls} option}). Substitute URLs can be either HTTP or HTTPS. HTTPS is recommended because communications are encrypted; conversely, using HTTP makes all communications visible to an eavesdropper, who could use the information gathered to determine, for instance, whether your system has unpatched security vulnerabilities. Substitutes from the official build farm are enabled by default when using Guix System (@pxref{GNU Distribution}). However, they are disabled by default when using Guix on a foreign distribution, unless you have explicitly enabled them via one of the recommended installation steps (@pxref{Installation}). The following paragraphs describe how to enable or disable substitutes for the official build farm; the same procedure can also be used to enable substitutes for any other substitute server. @node Substitute Server Authorization @subsection Substitute Server Authorization @cindex security @cindex substitutes, authorization thereof @cindex access control list (ACL), for substitutes @cindex ACL (access control list), for substitutes To allow Guix to download substitutes from @code{@value{SUBSTITUTE-SERVER}} or a mirror thereof, you must add its public key to the access control list (ACL) of archive imports, using the @command{guix archive} command (@pxref{Invoking guix archive}). Doing so implies that you trust @code{@value{SUBSTITUTE-SERVER}} to not be compromised and to serve genuine substitutes. @quotation Note If you are using Guix System, you can skip this section: Guix System authorizes substitutes from @code{@value{SUBSTITUTE-SERVER}} by default. @end quotation The public key for @code{@value{SUBSTITUTE-SERVER}} is installed along with Guix, in @code{@var{prefix}/share/guix/@value{SUBSTITUTE-SERVER}.pub}, where @var{prefix} is the installation prefix of Guix. If you installed Guix from source, make sure you checked the GPG signature of @file{guix-@value{VERSION}.tar.gz}, which contains this public key file. Then, you can run something like this: @example # guix archive --authorize < @var{prefix}/share/guix/@value{SUBSTITUTE-SERVER}.pub @end example Once this is in place, the output of a command like @code{guix build} should change from something like: @example $ guix build emacs --dry-run The following derivations would be built: /gnu/store/yr7bnx8xwcayd6j95r2clmkdl1qh688w-emacs-24.3.drv /gnu/store/x8qsh1hlhgjx6cwsjyvybnfv2i37z23w-dbus-1.6.4.tar.gz.drv /gnu/store/1ixwp12fl950d15h2cj11c73733jay0z-alsa-lib-1.0.27.1.tar.bz2.drv /gnu/store/nlma1pw0p603fpfiqy7kn4zm105r5dmw-util-linux-2.21.drv @dots{} @end example @noindent to something like: @example $ guix build emacs --dry-run 112.3 MB would be downloaded: /gnu/store/pk3n22lbq6ydamyymqkkz7i69wiwjiwi-emacs-24.3 /gnu/store/2ygn4ncnhrpr61rssa6z0d9x22si0va3-libjpeg-8d /gnu/store/71yz6lgx4dazma9dwn2mcjxaah9w77jq-cairo-1.12.16 /gnu/store/7zdhgp0n1518lvfn8mb96sxqfmvqrl7v-libxrender-0.9.7 @dots{} @end example @noindent The text changed from ``The following derivations would be built'' to ``112.3 MB would be downloaded''. This indicates that substitutes from @code{@value{SUBSTITUTE-SERVER}} are usable and will be downloaded, when possible, for future builds. @cindex substitutes, how to disable The substitute mechanism can be disabled globally by running @code{guix-daemon} with @option{--no-substitutes} (@pxref{Invoking guix-daemon}). It can also be disabled temporarily by passing the @option{--no-substitutes} option to @command{guix package}, @command{guix build}, and other command-line tools. @node Getting Substitutes from Other Servers @subsection Getting Substitutes from Other Servers @cindex substitute servers, adding more Guix can look up and fetch substitutes from several servers. This is useful when you are using packages from additional channels for which the official server does not have substitutes but another server provides them. Another situation where this is useful is when you would prefer to download from your organization's substitute server, resorting to the official server only as a fallback or dismissing it altogether. You can give Guix a list of substitute server URLs and it will check them in the specified order. You also need to explicitly authorize the public keys of substitute servers to instruct Guix to accept the substitutes they sign. On Guix System, this is achieved by modifying the configuration of the @code{guix} service. Since the @code{guix} service is part of the default lists of services, @code{%base-services} and @code{%desktop-services}, you can use @code{modify-services} to change its configuration and add the URLs and substitute keys that you want (@pxref{Service Reference, @code{modify-services}}). As an example, suppose you want to fetch substitutes from @code{guix.example.org} and to authorize the signing key of that server, in addition to the default @code{@value{SUBSTITUTE-SERVER}}. The resulting operating system configuration will look something like: @lisp (operating-system ;; @dots{} (services ;; Assume we're starting from '%desktop-services'. Replace it ;; with the list of services you're actually using. (modify-services %desktop-services (guix-service-type config => (guix-configuration (inherit config) (substitute-urls (append (list "https://guix.example.org") %default-substitute-urls)) (authorized-keys (append (list (local-file "./key.pub")) %default-authorized-guix-keys))))))) @end lisp This assumes that the file @file{key.pub} contains the signing key of @code{guix.example.org}. With this change in place in your operating system configuration file (say @file{/etc/config.scm}), you can reconfigure and restart the @code{guix-daemon} service or reboot so the changes take effect: @example $ sudo guix system reconfigure /etc/config.scm $ sudo herd restart guix-daemon @end example If you're running Guix on a ``foreign distro'', you would instead take the following steps to get substitutes from additional servers: @enumerate @item Edit the service configuration file for @code{guix-daemon}; when using systemd, this is normally @file{/etc/systemd/system/guix-daemon.service}. Add the @option{--substitute-urls} option on the @command{guix-daemon} command line and list the URLs of interest (@pxref{daemon-substitute-urls, @code{guix-daemon --substitute-urls}}): @example @dots{} --substitute-urls='https://guix.example.org https://@value{SUBSTITUTE-SERVER}' @end example @item Restart the daemon. For systemd, it goes like this: @example systemctl daemon-reload systemctl restart guix-daemon.service @end example @item Authorize the key of the new server (@pxref{Invoking guix archive}): @example guix archive --authorize < key.pub @end example Again this assumes @file{key.pub} contains the public key that @code{guix.example.org} uses to sign substitutes. @end enumerate Now you're all set! Substitutes will be preferably taken from @code{https://guix.example.org}, using @code{@value{SUBSTITUTE-SERVER}} as a fallback. Of course you can list as many substitute servers as you like, with the caveat that substitute lookup can be slowed down if too many servers need to be contacted. Note that there are also situations where one may want to add the URL of a substitute server @emph{without} authorizing its key. @xref{Substitute Authentication}, to understand this fine point. @node Substitute Authentication @subsection Substitute Authentication @cindex digital signatures Guix detects and raises an error when attempting to use a substitute that has been tampered with. Likewise, it ignores substitutes that are not signed, or that are not signed by one of the keys listed in the ACL. There is one exception though: if an unauthorized server provides substitutes that are @emph{bit-for-bit identical} to those provided by an authorized server, then the unauthorized server becomes eligible for downloads. For example, assume we have chosen two substitute servers with this option: @example --substitute-urls="https://a.example.org https://b.example.org" @end example @noindent @cindex reproducible builds If the ACL contains only the key for @samp{b.example.org}, and if @samp{a.example.org} happens to serve the @emph{exact same} substitutes, then Guix will download substitutes from @samp{a.example.org} because it comes first in the list and can be considered a mirror of @samp{b.example.org}. In practice, independent build machines usually produce the same binaries, thanks to bit-reproducible builds (see below). When using HTTPS, the server's X.509 certificate is @emph{not} validated (in other words, the server is not authenticated), contrary to what HTTPS clients such as Web browsers usually do. This is because Guix authenticates substitute information itself, as explained above, which is what we care about (whereas X.509 certificates are about authenticating bindings between domain names and public keys). @node Proxy Settings @subsection Proxy Settings @vindex http_proxy @vindex https_proxy Substitutes are downloaded over HTTP or HTTPS. The @env{http_proxy} and @env{https_proxy} environment variables can be set in the environment of @command{guix-daemon} and are honored for downloads of substitutes. Note that the value of those environment variables in the environment where @command{guix build}, @command{guix package}, and other client commands are run has @emph{absolutely no effect}. @node Substitution Failure @subsection Substitution Failure Even when a substitute for a derivation is available, sometimes the substitution attempt will fail. This can happen for a variety of reasons: the substitute server might be offline, the substitute may recently have been deleted, the connection might have been interrupted, etc. When substitutes are enabled and a substitute for a derivation is available, but the substitution attempt fails, Guix will attempt to build the derivation locally depending on whether or not @option{--fallback} was given (@pxref{fallback-option,, common build option @option{--fallback}}). Specifically, if @option{--fallback} was omitted, then no local build will be performed, and the derivation is considered to have failed. However, if @option{--fallback} was given, then Guix will attempt to build the derivation locally, and the success or failure of the derivation depends on the success or failure of the local build. Note that when substitutes are disabled or no substitute is available for the derivation in question, a local build will @emph{always} be performed, regardless of whether or not @option{--fallback} was given. To get an idea of how many substitutes are available right now, you can try running the @command{guix weather} command (@pxref{Invoking guix weather}). This command provides statistics on the substitutes provided by a server. @node On Trusting Binaries @subsection On Trusting Binaries @cindex trust, of pre-built binaries Today, each individual's control over their own computing is at the mercy of institutions, corporations, and groups with enough power and determination to subvert the computing infrastructure and exploit its weaknesses. While using @code{@value{SUBSTITUTE-SERVER}} substitutes can be convenient, we encourage users to also build on their own, or even run their own build farm, such that @code{@value{SUBSTITUTE-SERVER}} is less of an interesting target. One way to help is by publishing the software you build using @command{guix publish} so that others have one more choice of server to download substitutes from (@pxref{Invoking guix publish}). Guix has the foundations to maximize build reproducibility (@pxref{Features}). In most cases, independent builds of a given package or derivation should yield bit-identical results. Thus, through a diverse set of independent package builds, we can strengthen the integrity of our systems. The @command{guix challenge} command aims to help users assess substitute servers, and to assist developers in finding out about non-deterministic package builds (@pxref{Invoking guix challenge}). Similarly, the @option{--check} option of @command{guix build} allows users to check whether previously-installed substitutes are genuine by rebuilding them locally (@pxref{build-check, @command{guix build --check}}). In the future, we want Guix to have support to publish and retrieve binaries to/from other users, in a peer-to-peer fashion. If you would like to discuss this project, join us on @email{guix-devel@@gnu.org}. @node Packages with Multiple Outputs @section Packages with Multiple Outputs @cindex multiple-output packages @cindex package outputs @cindex outputs Often, packages defined in Guix have a single @dfn{output}---i.e., the source package leads to exactly one directory in the store. When running @command{guix install glibc}, one installs the default output of the GNU libc package; the default output is called @code{out}, but its name can be omitted as shown in this command. In this particular case, the default output of @code{glibc} contains all the C header files, shared libraries, static libraries, Info documentation, and other supporting files. Sometimes it is more appropriate to separate the various types of files produced from a single source package into separate outputs. For instance, the GLib C library (used by GTK+ and related packages) installs more than 20 MiB of reference documentation as HTML pages. To save space for users who do not need it, the documentation goes to a separate output, called @code{doc}. To install the main GLib output, which contains everything but the documentation, one would run: @example guix install glib @end example @cindex documentation The command to install its documentation is: @example guix install glib:doc @end example Some packages install programs with different ``dependency footprints''. For instance, the WordNet package installs both command-line tools and graphical user interfaces (GUIs). The former depend solely on the C library, whereas the latter depend on Tcl/Tk and the underlying X libraries. In this case, we leave the command-line tools in the default output, whereas the GUIs are in a separate output. This allows users who do not need the GUIs to save space. The @command{guix size} command can help find out about such situations (@pxref{Invoking guix size}). @command{guix graph} can also be helpful (@pxref{Invoking guix graph}). There are several such multiple-output packages in the GNU distribution. Other conventional output names include @code{lib} for libraries and possibly header files, @code{bin} for stand-alone programs, and @code{debug} for debugging information (@pxref{Installing Debugging Files}). The outputs of a packages are listed in the third column of the output of @command{guix package --list-available} (@pxref{Invoking guix package}). @node Invoking guix gc @section Invoking @command{guix gc} @cindex garbage collector @cindex disk space Packages that are installed, but not used, may be @dfn{garbage-collected}. The @command{guix gc} command allows users to explicitly run the garbage collector to reclaim space from the @file{/gnu/store} directory. It is the @emph{only} way to remove files from @file{/gnu/store}---removing files or directories manually may break it beyond repair! @cindex GC roots @cindex garbage collector roots The garbage collector has a set of known @dfn{roots}: any file under @file{/gnu/store} reachable from a root is considered @dfn{live} and cannot be deleted; any other file is considered @dfn{dead} and may be deleted. The set of garbage collector roots (``GC roots'' for short) includes default user profiles; by default, the symlinks under @file{/var/guix/gcroots} represent these GC roots. New GC roots can be added with @command{guix build --root}, for example (@pxref{Invoking guix build}). The @command{guix gc --list-roots} command lists them. Prior to running @code{guix gc --collect-garbage} to make space, it is often useful to remove old generations from user profiles; that way, old package builds referenced by those generations can be reclaimed. This is achieved by running @code{guix package --delete-generations} (@pxref{Invoking guix package}). Our recommendation is to run a garbage collection periodically, or when you are short on disk space. For instance, to guarantee that at least 5@tie{}GB are available on your disk, simply run: @example guix gc -F 5G @end example It is perfectly safe to run as a non-interactive periodic job (@pxref{Scheduled Job Execution}, for how to set up such a job). Running @command{guix gc} with no arguments will collect as much garbage as it can, but that is often inconvenient: you may find yourself having to rebuild or re-download software that is ``dead'' from the GC viewpoint but that is necessary to build other pieces of software---e.g., the compiler tool chain. The @command{guix gc} command has three modes of operation: it can be used to garbage-collect any dead files (the default), to delete specific files (the @option{--delete} option), to print garbage-collector information, or for more advanced queries. The garbage collection options are as follows: @table @code @item --collect-garbage[=@var{min}] @itemx -C [@var{min}] Collect garbage---i.e., unreachable @file{/gnu/store} files and sub-directories. This is the default operation when no option is specified. When @var{min} is given, stop once @var{min} bytes have been collected. @var{min} may be a number of bytes, or it may include a unit as a suffix, such as @code{MiB} for mebibytes and @code{GB} for gigabytes (@pxref{Block size, size specifications,, coreutils, GNU Coreutils}). When @var{min} is omitted, collect all the garbage. @item --free-space=@var{free} @itemx -F @var{free} Collect garbage until @var{free} space is available under @file{/gnu/store}, if possible; @var{free} denotes storage space, such as @code{500MiB}, as described above. When @var{free} or more is already available in @file{/gnu/store}, do nothing and exit immediately. @item --delete-generations[=@var{duration}] @itemx -d [@var{duration}] Before starting the garbage collection process, delete all the generations older than @var{duration}, for all the user profiles; when run as root, this applies to all the profiles @emph{of all the users}. For example, this command deletes all the generations of all your profiles that are older than 2 months (except generations that are current), and then proceeds to free space until at least 10 GiB are available: @example guix gc -d 2m -F 10G @end example @item --delete @itemx -D Attempt to delete all the store files and directories specified as arguments. This fails if some of the files are not in the store, or if they are still live. @item --list-failures List store items corresponding to cached build failures. This prints nothing unless the daemon was started with @option{--cache-failures} (@pxref{Invoking guix-daemon, @option{--cache-failures}}). @item --list-roots List the GC roots owned by the user; when run as root, list @emph{all} the GC roots. @item --list-busy List store items in use by currently running processes. These store items are effectively considered GC roots: they cannot be deleted. @item --clear-failures Remove the specified store items from the failed-build cache. Again, this option only makes sense when the daemon is started with @option{--cache-failures}. Otherwise, it does nothing. @item --list-dead Show the list of dead files and directories still present in the store---i.e., files and directories no longer reachable from any root. @item --list-live Show the list of live store files and directories. @end table In addition, the references among existing store files can be queried: @table @code @item --references @itemx --referrers @cindex package dependencies List the references (respectively, the referrers) of store files given as arguments. @item --requisites @itemx -R @cindex closure List the requisites of the store files passed as arguments. Requisites include the store files themselves, their references, and the references of these, recursively. In other words, the returned list is the @dfn{transitive closure} of the store files. @xref{Invoking guix size}, for a tool to profile the size of the closure of an element. @xref{Invoking guix graph}, for a tool to visualize the graph of references. @item --derivers @cindex derivation Return the derivation(s) leading to the given store items (@pxref{Derivations}). For example, this command: @example guix gc --derivers `guix package -I ^emacs$ | cut -f4` @end example @noindent returns the @file{.drv} file(s) leading to the @code{emacs} package installed in your profile. Note that there may be zero matching @file{.drv} files, for instance because these files have been garbage-collected. There can also be more than one matching @file{.drv} due to fixed-output derivations. @end table Lastly, the following options allow you to check the integrity of the store and to control disk usage. @table @option @item --verify[=@var{options}] @cindex integrity, of the store @cindex integrity checking Verify the integrity of the store. By default, make sure that all the store items marked as valid in the database of the daemon actually exist in @file{/gnu/store}. When provided, @var{options} must be a comma-separated list containing one or more of @code{contents} and @code{repair}. When passing @option{--verify=contents}, the daemon computes the content hash of each store item and compares it against its hash in the database. Hash mismatches are reported as data corruptions. Because it traverses @emph{all the files in the store}, this command can take a long time, especially on systems with a slow disk drive. @cindex repairing the store @cindex corruption, recovering from Using @option{--verify=repair} or @option{--verify=contents,repair} causes the daemon to try to repair corrupt store items by fetching substitutes for them (@pxref{Substitutes}). Because repairing is not atomic, and thus potentially dangerous, it is available only to the system administrator. A lightweight alternative, when you know exactly which items in the store are corrupt, is @command{guix build --repair} (@pxref{Invoking guix build}). @item --optimize @cindex deduplication Optimize the store by hard-linking identical files---this is @dfn{deduplication}. The daemon performs deduplication after each successful build or archive import, unless it was started with @option{--disable-deduplication} (@pxref{Invoking guix-daemon, @option{--disable-deduplication}}). Thus, this option is primarily useful when the daemon was running with @option{--disable-deduplication}. @end table @node Invoking guix pull @section Invoking @command{guix pull} @cindex upgrading Guix @cindex updating Guix @cindex @command{guix pull} @cindex pull @cindex security, @command{guix pull} @cindex authenticity, of code obtained with @command{guix pull} Packages are installed or upgraded to the latest version available in the distribution currently available on your local machine. To update that distribution, along with the Guix tools, you must run @command{guix pull}: the command downloads the latest Guix source code and package descriptions, and deploys it. Source code is downloaded from a @uref{https://git-scm.com, Git} repository, by default the official GNU@tie{}Guix repository, though this can be customized. @command{guix pull} ensures that the code it downloads is @emph{authentic} by verifying that commits are signed by Guix developers. Specifically, @command{guix pull} downloads code from the @dfn{channels} (@pxref{Channels}) specified by one of the followings, in this order: @enumerate @item the @option{--channels} option; @item the user's @file{~/.config/guix/channels.scm} file; @item the system-wide @file{/etc/guix/channels.scm} file; @item the built-in default channels specified in the @code{%default-channels} variable. @end enumerate On completion, @command{guix package} will use packages and package versions from this just-retrieved copy of Guix. Not only that, but all the Guix commands and Scheme modules will also be taken from that latest version. New @command{guix} sub-commands added by the update also become available. Any user can update their Guix copy using @command{guix pull}, and the effect is limited to the user who ran @command{guix pull}. For instance, when user @code{root} runs @command{guix pull}, this has no effect on the version of Guix that user @code{alice} sees, and vice versa. The result of running @command{guix pull} is a @dfn{profile} available under @file{~/.config/guix/current} containing the latest Guix. Thus, make sure to add it to the beginning of your search path so that you use the latest version, and similarly for the Info manual (@pxref{Documentation}): @example export PATH="$HOME/.config/guix/current/bin:$PATH" export INFOPATH="$HOME/.config/guix/current/share/info:$INFOPATH" @end example The @option{--list-generations} or @option{-l} option lists past generations produced by @command{guix pull}, along with details about their provenance: @example $ guix pull -l Generation 1 Jun 10 2018 00:18:18 guix 65956ad repository URL: https://git.savannah.gnu.org/git/guix.git branch: origin/master commit: 65956ad3526ba09e1f7a40722c96c6ef7c0936fe Generation 2 Jun 11 2018 11:02:49 guix e0cc7f6 repository URL: https://git.savannah.gnu.org/git/guix.git branch: origin/master commit: e0cc7f669bec22c37481dd03a7941c7d11a64f1d 2 new packages: keepalived, libnfnetlink 6 packages upgraded: emacs-nix-mode@@2.0.4, guile2.0-guix@@0.14.0-12.77a1aac, guix@@0.14.0-12.77a1aac, heimdal@@7.5.0, milkytracker@@1.02.00, nix@@2.0.4 Generation 3 Jun 13 2018 23:31:07 (current) guix 844cc1c repository URL: https://git.savannah.gnu.org/git/guix.git branch: origin/master commit: 844cc1c8f394f03b404c5bb3aee086922373490c 28 new packages: emacs-helm-ls-git, emacs-helm-mu, @dots{} 69 packages upgraded: borg@@1.1.6, cheese@@3.28.0, @dots{} @end example @xref{Invoking guix describe, @command{guix describe}}, for other ways to describe the current status of Guix. This @code{~/.config/guix/current} profile works exactly like the profiles created by @command{guix package} (@pxref{Invoking guix package}). That is, you can list generations, roll back to the previous generation---i.e., the previous Guix---and so on: @example $ guix pull --roll-back switched from generation 3 to 2 $ guix pull --delete-generations=1 deleting /var/guix/profiles/per-user/charlie/current-guix-1-link @end example You can also use @command{guix package} (@pxref{Invoking guix package}) to manage the profile by naming it explicitly: @example $ guix package -p ~/.config/guix/current --roll-back switched from generation 3 to 2 $ guix package -p ~/.config/guix/current --delete-generations=1 deleting /var/guix/profiles/per-user/charlie/current-guix-1-link @end example The @command{guix pull} command is usually invoked with no arguments, but it supports the following options: @table @code @item --url=@var{url} @itemx --commit=@var{commit} @itemx --branch=@var{branch} Download code for the @code{guix} channel from the specified @var{url}, at the given @var{commit} (a valid Git commit ID represented as a hexadecimal string), or @var{branch}. @cindex @file{channels.scm}, configuration file @cindex configuration file for channels These options are provided for convenience, but you can also specify your configuration in the @file{~/.config/guix/channels.scm} file or using the @option{--channels} option (see below). @item --channels=@var{file} @itemx -C @var{file} Read the list of channels from @var{file} instead of @file{~/.config/guix/channels.scm} or @file{/etc/guix/channels.scm}. @var{file} must contain Scheme code that evaluates to a list of channel objects. @xref{Channels}, for more information. @cindex channel news @item --news @itemx -N Display the list of packages added or upgraded since the previous generation, as well as, occasionally, news written by channel authors for their users (@pxref{Channels, Writing Channel News}). The package information is the same as displayed upon @command{guix pull} completion, but without ellipses; it is also similar to the output of @command{guix pull -l} for the last generation (see below). @item --list-generations[=@var{pattern}] @itemx -l [@var{pattern}] List all the generations of @file{~/.config/guix/current} or, if @var{pattern} is provided, the subset of generations that match @var{pattern}. The syntax of @var{pattern} is the same as with @code{guix package --list-generations} (@pxref{Invoking guix package}). @item --roll-back @cindex rolling back @cindex undoing transactions @cindex transactions, undoing Roll back to the previous @dfn{generation} of @file{~/.config/guix/current}---i.e., undo the last transaction. @item --switch-generation=@var{pattern} @itemx -S @var{pattern} @cindex generations Switch to a particular generation defined by @var{pattern}. @var{pattern} may be either a generation number or a number prefixed with ``+'' or ``-''. The latter means: move forward/backward by a specified number of generations. For example, if you want to return to the latest generation after @option{--roll-back}, use @option{--switch-generation=+1}. @item --delete-generations[=@var{pattern}] @itemx -d [@var{pattern}] When @var{pattern} is omitted, delete all generations except the current one. This command accepts the same patterns as @option{--list-generations}. When @var{pattern} is specified, delete the matching generations. When @var{pattern} specifies a duration, generations @emph{older} than the specified duration match. For instance, @option{--delete-generations=1m} deletes generations that are more than one month old. If the current generation matches, it is @emph{not} deleted. Note that deleting generations prevents rolling back to them. Consequently, this command must be used with care. @xref{Invoking guix describe}, for a way to display information about the current generation only. @item --profile=@var{profile} @itemx -p @var{profile} Use @var{profile} instead of @file{~/.config/guix/current}. @item --dry-run @itemx -n Show which channel commit(s) would be used and what would be built or substituted but do not actually do it. @item --allow-downgrades Allow pulling older or unrelated revisions of channels than those currently in use. @cindex downgrade attacks, protection against By default, @command{guix pull} protects against so-called ``downgrade attacks'' whereby the Git repository of a channel would be reset to an earlier or unrelated revision of itself, potentially leading you to install older, known-vulnerable versions of software packages. @quotation Note Make sure you understand its security implications before using @option{--allow-downgrades}. @end quotation @item --disable-authentication Allow pulling channel code without authenticating it. @cindex authentication, of channel code By default, @command{guix pull} authenticates code downloaded from channels by verifying that its commits are signed by authorized developers, and raises an error if this is not the case. This option instructs it to not perform any such verification. @quotation Note Make sure you understand its security implications before using @option{--disable-authentication}. @end quotation @item --system=@var{system} @itemx -s @var{system} Attempt to build for @var{system}---e.g., @code{i686-linux}---instead of the system type of the build host. @item --bootstrap Use the bootstrap Guile to build the latest Guix. This option is only useful to Guix developers. @end table The @dfn{channel} mechanism allows you to instruct @command{guix pull} which repository and branch to pull from, as well as @emph{additional} repositories containing package modules that should be deployed. @xref{Channels}, for more information. In addition, @command{guix pull} supports all the common build options (@pxref{Common Build Options}). @node Invoking guix time-machine @section Invoking @command{guix time-machine} @cindex @command{guix time-machine} @cindex pinning, channels @cindex replicating Guix @cindex reproducibility, of Guix The @command{guix time-machine} command provides access to other revisions of Guix, for example to install older versions of packages, or to reproduce a computation in an identical environment. The revision of Guix to be used is defined by a commit or by a channel description file created by @command{guix describe} (@pxref{Invoking guix describe}). The general syntax is: @example guix time-machine @var{options}@dots{} -- @var{command} @var {arg}@dots{} @end example where @var{command} and @var{arg}@dots{} are passed unmodified to the @command{guix} command of the specified revision. The @var{options} that define this revision are the same as for @command{guix pull} (@pxref{Invoking guix pull}): @table @code @item --url=@var{url} @itemx --commit=@var{commit} @itemx --branch=@var{branch} Use the @code{guix} channel from the specified @var{url}, at the given @var{commit} (a valid Git commit ID represented as a hexadecimal string), or @var{branch}. @item --channels=@var{file} @itemx -C @var{file} Read the list of channels from @var{file}. @var{file} must contain Scheme code that evaluates to a list of channel objects. @xref{Channels} for more information. @end table As for @command{guix pull}, the absence of any options means that the latest commit on the master branch will be used. The command @example guix time-machine -- build hello @end example will thus build the package @code{hello} as defined in the master branch, which is in general a newer revision of Guix than you have installed. Time travel works in both directions! Note that @command{guix time-machine} can trigger builds of channels and their dependencies, and these are controlled by the standard build options (@pxref{Common Build Options}). @node Inferiors @section Inferiors @c TODO: Remove this once we're more confident about API stability. @quotation Note The functionality described here is a ``technology preview'' as of version @value{VERSION}. As such, the interface is subject to change. @end quotation @cindex inferiors @cindex composition of Guix revisions Sometimes you might need to mix packages from the revision of Guix you're currently running with packages available in a different revision of Guix. Guix @dfn{inferiors} allow you to achieve that by composing different Guix revisions in arbitrary ways. @cindex inferior packages Technically, an ``inferior'' is essentially a separate Guix process connected to your main Guix process through a REPL (@pxref{Invoking guix repl}). The @code{(guix inferior)} module allows you to create inferiors and to communicate with them. It also provides a high-level interface to browse and manipulate the packages that an inferior provides---@dfn{inferior packages}. When combined with channels (@pxref{Channels}), inferiors provide a simple way to interact with a separate revision of Guix. For example, let's assume you want to install in your profile the current @code{guile} package, along with the @code{guile-json} as it existed in an older revision of Guix---perhaps because the newer @code{guile-json} has an incompatible API and you want to run your code against the old API@. To do that, you could write a manifest for use by @code{guix package --manifest} (@pxref{Invoking guix package}); in that manifest, you would create an inferior for that old Guix revision you care about, and you would look up the @code{guile-json} package in the inferior: @lisp (use-modules (guix inferior) (guix channels) (srfi srfi-1)) ;for 'first' (define channels ;; This is the old revision from which we want to ;; extract guile-json. (list (channel (name 'guix) (url "https://git.savannah.gnu.org/git/guix.git") (commit "65956ad3526ba09e1f7a40722c96c6ef7c0936fe")))) (define inferior ;; An inferior representing the above revision. (inferior-for-channels channels)) ;; Now create a manifest with the current "guile" package ;; and the old "guile-json" package. (packages->manifest (list (first (lookup-inferior-packages inferior "guile-json")) (specification->package "guile"))) @end lisp On its first run, @command{guix package --manifest} might have to build the channel you specified before it can create the inferior; subsequent runs will be much faster because the Guix revision will be cached. The @code{(guix inferior)} module provides the following procedures to open an inferior: @deffn {Scheme Procedure} inferior-for-channels @var{channels} @ [#:cache-directory] [#:ttl] Return an inferior for @var{channels}, a list of channels. Use the cache at @var{cache-directory}, where entries can be reclaimed after @var{ttl} seconds. This procedure opens a new connection to the build daemon. As a side effect, this procedure may build or substitute binaries for @var{channels}, which can take time. @end deffn @deffn {Scheme Procedure} open-inferior @var{directory} @ [#:command "bin/guix"] Open the inferior Guix in @var{directory}, running @code{@var{directory}/@var{command} repl} or equivalent. Return @code{#f} if the inferior could not be launched. @end deffn @cindex inferior packages The procedures listed below allow you to obtain and manipulate inferior packages. @deffn {Scheme Procedure} inferior-packages @var{inferior} Return the list of packages known to @var{inferior}. @end deffn @deffn {Scheme Procedure} lookup-inferior-packages @var{inferior} @var{name} @ [@var{version}] Return the sorted list of inferior packages matching @var{name} in @var{inferior}, with highest version numbers first. If @var{version} is true, return only packages with a version number prefixed by @var{version}. @end deffn @deffn {Scheme Procedure} inferior-package? @var{obj} Return true if @var{obj} is an inferior package. @end deffn @deffn {Scheme Procedure} inferior-package-name @var{package} @deffnx {Scheme Procedure} inferior-package-version @var{package} @deffnx {Scheme Procedure} inferior-package-synopsis @var{package} @deffnx {Scheme Procedure} inferior-package-description @var{package} @deffnx {Scheme Procedure} inferior-package-home-page @var{package} @deffnx {Scheme Procedure} inferior-package-location @var{package} @deffnx {Scheme Procedure} inferior-package-inputs @var{package} @deffnx {Scheme Procedure} inferior-package-native-inputs @var{package} @deffnx {Scheme Procedure} inferior-package-propagated-inputs @var{package} @deffnx {Scheme Procedure} inferior-package-transitive-propagated-inputs @var{package} @deffnx {Scheme Procedure} inferior-package-native-search-paths @var{package} @deffnx {Scheme Procedure} inferior-package-transitive-native-search-paths @var{package} @deffnx {Scheme Procedure} inferior-package-search-paths @var{package} These procedures are the counterpart of package record accessors (@pxref{package Reference}). Most of them work by querying the inferior @var{package} comes from, so the inferior must still be live when you call these procedures. @end deffn Inferior packages can be used transparently like any other package or file-like object in G-expressions (@pxref{G-Expressions}). They are also transparently handled by the @code{packages->manifest} procedure, which is commonly use in manifests (@pxref{Invoking guix package, the @option{--manifest} option of @command{guix package}}). Thus you can insert an inferior package pretty much anywhere you would insert a regular package: in manifests, in the @code{packages} field of your @code{operating-system} declaration, and so on. @node Invoking guix describe @section Invoking @command{guix describe} @cindex reproducibility @cindex replicating Guix Often you may want to answer questions like: ``Which revision of Guix am I using?'' or ``Which channels am I using?'' This is useful information in many situations: if you want to @emph{replicate} an environment on a different machine or user account, if you want to report a bug or to determine what change in the channels you are using caused it, or if you want to record your system state for reproducibility purposes. The @command{guix describe} command answers these questions. When run from a @command{guix pull}ed @command{guix}, @command{guix describe} displays the channel(s) that it was built from, including their repository URL and commit IDs (@pxref{Channels}): @example $ guix describe Generation 10 Sep 03 2018 17:32:44 (current) guix e0fa68c repository URL: https://git.savannah.gnu.org/git/guix.git branch: master commit: e0fa68c7718fffd33d81af415279d6ddb518f727 @end example If you're familiar with the Git version control system, this is similar in spirit to @command{git describe}; the output is also similar to that of @command{guix pull --list-generations}, but limited to the current generation (@pxref{Invoking guix pull, the @option{--list-generations} option}). Because the Git commit ID shown above unambiguously refers to a snapshot of Guix, this information is all it takes to describe the revision of Guix you're using, and also to replicate it. To make it easier to replicate Guix, @command{guix describe} can also be asked to return a list of channels instead of the human-readable description above: @example $ guix describe -f channels (list (channel (name 'guix) (url "https://git.savannah.gnu.org/git/guix.git") (commit "e0fa68c7718fffd33d81af415279d6ddb518f727") (introduction (make-channel-introduction "9edb3f66fd807b096b48283debdcddccfea34bad" (openpgp-fingerprint "BBB0 2DDF 2CEA F6A8 0D1D E643 A2A0 6DF2 A33A 54FA"))))) @end example @noindent You can save this to a file and feed it to @command{guix pull -C} on some other machine or at a later point in time, which will instantiate @emph{this exact Guix revision} (@pxref{Invoking guix pull, the @option{-C} option}). From there on, since you're able to deploy the same revision of Guix, you can just as well @emph{replicate a complete software environment}. We humbly think that this is @emph{awesome}, and we hope you'll like it too! The details of the options supported by @command{guix describe} are as follows: @table @code @item --format=@var{format} @itemx -f @var{format} Produce output in the specified @var{format}, one of: @table @code @item human produce human-readable output; @item channels produce a list of channel specifications that can be passed to @command{guix pull -C} or installed as @file{~/.config/guix/channels.scm} (@pxref{Invoking guix pull}); @item channels-sans-intro like @code{channels}, but omit the @code{introduction} field; use it to produce a channel specification suitable for Guix version 1.1.0 or earlier---the @code{introduction} field has to do with channel authentication (@pxref{Channels, Channel Authentication}) and is not supported by these older versions; @item json @cindex JSON produce a list of channel specifications in JSON format; @item recutils produce a list of channel specifications in Recutils format. @end table @item --list-formats Display available formats for @option{--format} option. @item --profile=@var{profile} @itemx -p @var{profile} Display information about @var{profile}. @end table @node Invoking guix archive @section Invoking @command{guix archive} @cindex @command{guix archive} @cindex archive The @command{guix archive} command allows users to @dfn{export} files from the store into a single archive, and to later @dfn{import} them on a machine that runs Guix. In particular, it allows store files to be transferred from one machine to the store on another machine. @quotation Note If you're looking for a way to produce archives in a format suitable for tools other than Guix, @pxref{Invoking guix pack}. @end quotation @cindex exporting store items To export store files as an archive to standard output, run: @example guix archive --export @var{options} @var{specifications}... @end example @var{specifications} may be either store file names or package specifications, as for @command{guix package} (@pxref{Invoking guix package}). For instance, the following command creates an archive containing the @code{gui} output of the @code{git} package and the main output of @code{emacs}: @example guix archive --export git:gui /gnu/store/...-emacs-24.3 > great.nar @end example If the specified packages are not built yet, @command{guix archive} automatically builds them. The build process may be controlled with the common build options (@pxref{Common Build Options}). To transfer the @code{emacs} package to a machine connected over SSH, one would run: @example guix archive --export -r emacs | ssh the-machine guix archive --import @end example @noindent Similarly, a complete user profile may be transferred from one machine to another like this: @example guix archive --export -r $(readlink -f ~/.guix-profile) | \ ssh the-machine guix archive --import @end example @noindent However, note that, in both examples, all of @code{emacs} and the profile as well as all of their dependencies are transferred (due to @option{-r}), regardless of what is already available in the store on the target machine. The @option{--missing} option can help figure out which items are missing from the target store. The @command{guix copy} command simplifies and optimizes this whole process, so this is probably what you should use in this case (@pxref{Invoking guix copy}). @cindex nar, archive format @cindex normalized archive (nar) @cindex nar bundle, archive format Each store item is written in the @dfn{normalized archive} or @dfn{nar} format (described below), and the output of @command{guix archive --export} (and input of @command{guix archive --import}) is a @dfn{nar bundle}. The nar format is comparable in spirit to `tar', but with differences that make it more appropriate for our purposes. First, rather than recording all Unix metadata for each file, the nar format only mentions the file type (regular, directory, or symbolic link); Unix permissions and owner/group are dismissed. Second, the order in which directory entries are stored always follows the order of file names according to the C locale collation order. This makes archive production fully deterministic. That nar bundle format is essentially the concatenation of zero or more nars along with metadata for each store item it contains: its file name, references, corresponding derivation, and a digital signature. When exporting, the daemon digitally signs the contents of the archive, and that digital signature is appended. When importing, the daemon verifies the signature and rejects the import in case of an invalid signature or if the signing key is not authorized. @c FIXME: Add xref to daemon doc about signatures. The main options are: @table @code @item --export Export the specified store files or packages (see below). Write the resulting archive to the standard output. Dependencies are @emph{not} included in the output, unless @option{--recursive} is passed. @item -r @itemx --recursive When combined with @option{--export}, this instructs @command{guix archive} to include dependencies of the given items in the archive. Thus, the resulting archive is self-contained: it contains the closure of the exported store items. @item --import Read an archive from the standard input, and import the files listed therein into the store. Abort if the archive has an invalid digital signature, or if it is signed by a public key not among the authorized keys (see @option{--authorize} below). @item --missing Read a list of store file names from the standard input, one per line, and write on the standard output the subset of these files missing from the store. @item --generate-key[=@var{parameters}] @cindex signing, archives Generate a new key pair for the daemon. This is a prerequisite before archives can be exported with @option{--export}. This operation is usually instantaneous but it can take time if the system's entropy pool needs to be refilled. On Guix System, @code{guix-service-type} takes care of generating this key pair the first boot. The generated key pair is typically stored under @file{/etc/guix}, in @file{signing-key.pub} (public key) and @file{signing-key.sec} (private key, which must be kept secret). When @var{parameters} is omitted, an ECDSA key using the Ed25519 curve is generated, or, for Libgcrypt versions before 1.6.0, it is a 4096-bit RSA key. Alternatively, @var{parameters} can specify @code{genkey} parameters suitable for Libgcrypt (@pxref{General public-key related Functions, @code{gcry_pk_genkey},, gcrypt, The Libgcrypt Reference Manual}). @item --authorize @cindex authorizing, archives Authorize imports signed by the public key passed on standard input. The public key must be in ``s-expression advanced format''---i.e., the same format as the @file{signing-key.pub} file. The list of authorized keys is kept in the human-editable file @file{/etc/guix/acl}. The file contains @url{https://people.csail.mit.edu/rivest/Sexp.txt, ``advanced-format s-expressions''} and is structured as an access-control list in the @url{https://theworld.com/~cme/spki.txt, Simple Public-Key Infrastructure (SPKI)}. @item --extract=@var{directory} @itemx -x @var{directory} Read a single-item archive as served by substitute servers (@pxref{Substitutes}) and extract it to @var{directory}. This is a low-level operation needed in only very narrow use cases; see below. For example, the following command extracts the substitute for Emacs served by @code{@value{SUBSTITUTE-SERVER}} to @file{/tmp/emacs}: @example $ wget -O - \ https://@value{SUBSTITUTE-SERVER}/nar/gzip/@dots{}-emacs-24.5 \ | gunzip | guix archive -x /tmp/emacs @end example Single-item archives are different from multiple-item archives produced by @command{guix archive --export}; they contain a single store item, and they do @emph{not} embed a signature. Thus this operation does @emph{no} signature verification and its output should be considered unsafe. The primary purpose of this operation is to facilitate inspection of archive contents coming from possibly untrusted substitute servers (@pxref{Invoking guix challenge}). @item --list @itemx -t Read a single-item archive as served by substitute servers (@pxref{Substitutes}) and print the list of files it contains, as in this example: @example $ wget -O - \ https://@value{SUBSTITUTE-SERVER}/nar/lzip/@dots{}-emacs-26.3 \ | lzip -d | guix archive -t @end example @end table @c ********************************************************************* @node Channels @chapter Channels @cindex channels @cindex @file{channels.scm}, configuration file @cindex configuration file for channels @cindex @command{guix pull}, configuration file @cindex configuration of @command{guix pull} Guix and its package collection are updated by running @command{guix pull} (@pxref{Invoking guix pull}). By default @command{guix pull} downloads and deploys Guix itself from the official GNU@tie{}Guix repository. This can be customized by defining @dfn{channels} in the @file{~/.config/guix/channels.scm} file. A channel specifies a URL and branch of a Git repository to be deployed, and @command{guix pull} can be instructed to pull from one or more channels. In other words, channels can be used to @emph{customize} and to @emph{extend} Guix, as we will see below. Guix is able to take into account security concerns and deal with authenticated updates. @menu * Specifying Additional Channels:: Extending the package collection. * Using a Custom Guix Channel:: Using a customized Guix. * Replicating Guix:: Running the @emph{exact same} Guix. * Channel Authentication:: How Guix verifies what it fetches. * Creating a Channel:: How to write your custom channel. * Package Modules in a Sub-directory:: Specifying the channel's package modules location. * Declaring Channel Dependencies:: How to depend on other channels. * Specifying Channel Authorizations:: Defining channel authors authorizations. * Primary URL:: Distinguishing mirror to original. * Writing Channel News:: Communicating information to channel's users. @end menu @node Specifying Additional Channels @section Specifying Additional Channels @cindex extending the package collection (channels) @cindex variant packages (channels) You can specify @emph{additional channels} to pull from. To use a channel, write @code{~/.config/guix/channels.scm} to instruct @command{guix pull} to pull from it @emph{in addition} to the default Guix channel(s): @vindex %default-channels @lisp ;; Add variant packages to those Guix provides. (cons (channel (name 'variant-packages) (url "https://example.org/variant-packages.git")) %default-channels) @end lisp @noindent Note that the snippet above is (as always!)@: Scheme code; we use @code{cons} to add a channel the list of channels that the variable @code{%default-channels} is bound to (@pxref{Pairs, @code{cons} and lists,, guile, GNU Guile Reference Manual}). With this file in place, @command{guix pull} builds not only Guix but also the package modules from your own repository. The result in @file{~/.config/guix/current} is the union of Guix with your own package modules: @example $ guix pull --list-generations @dots{} Generation 19 Aug 27 2018 16:20:48 guix d894ab8 repository URL: https://git.savannah.gnu.org/git/guix.git branch: master commit: d894ab8e9bfabcefa6c49d9ba2e834dd5a73a300 variant-packages dd3df5e repository URL: https://example.org/variant-packages.git branch: master commit: dd3df5e2c8818760a8fc0bd699e55d3b69fef2bb 11 new packages: variant-gimp, variant-emacs-with-cool-features, @dots{} 4 packages upgraded: emacs-racket-mode@@0.0.2-2.1b78827, @dots{} @end example @noindent The output of @command{guix pull} above shows that Generation@tie{}19 includes both Guix and packages from the @code{variant-personal-packages} channel. Among the new and upgraded packages that are listed, some like @code{variant-gimp} and @code{variant-emacs-with-cool-features} might come from @code{variant-packages}, while others come from the Guix default channel. @node Using a Custom Guix Channel @section Using a Custom Guix Channel The channel called @code{guix} specifies where Guix itself---its command-line tools as well as its package collection---should be downloaded. For instance, suppose you want to update from another copy of the Guix repository at @code{example.org}, and specifically the @code{super-hacks} branch, you can write in @code{~/.config/guix/channels.scm} this specification: @lisp ;; Tell 'guix pull' to use another repo. (list (channel (name 'guix) (url "https://example.org/another-guix.git") (branch "super-hacks"))) @end lisp @noindent From there on, @command{guix pull} will fetch code from the @code{super-hacks} branch of the repository at @code{example.org}. The authentication concern is addressed below ((@pxref{Channel Authentication}). @node Replicating Guix @section Replicating Guix @cindex pinning, channels @cindex replicating Guix @cindex reproducibility, of Guix The @command{guix pull --list-generations} output above shows precisely which commits were used to build this instance of Guix. We can thus replicate it, say, on another machine, by providing a channel specification in @file{~/.config/guix/channels.scm} that is ``pinned'' to these commits: @lisp ;; Deploy specific commits of my channels of interest. (list (channel (name 'guix) (url "https://git.savannah.gnu.org/git/guix.git") (commit "6298c3ffd9654d3231a6f25390b056483e8f407c")) (channel (name 'variant-packages) (url "https://example.org/variant-packages.git") (commit "dd3df5e2c8818760a8fc0bd699e55d3b69fef2bb"))) @end lisp The @command{guix describe --format=channels} command can even generate this list of channels directly (@pxref{Invoking guix describe}). The resulting file can be used with the -C options of @command{guix pull} (@pxref{Invoking guix pull}) or @command{guix time-machine} (@pxref{Invoking guix time-machine}). At this point the two machines run the @emph{exact same Guix}, with access to the @emph{exact same packages}. The output of @command{guix build gimp} on one machine will be exactly the same, bit for bit, as the output of the same command on the other machine. It also means both machines have access to all the source code of Guix and, transitively, to all the source code of every package it defines. This gives you super powers, allowing you to track the provenance of binary artifacts with very fine grain, and to reproduce software environments at will---some sort of ``meta reproducibility'' capabilities, if you will. @xref{Inferiors}, for another way to take advantage of these super powers. @node Channel Authentication @section Channel Authentication @anchor{channel-authentication} @cindex authentication, of channel code The @command{guix pull} and @command{guix time-machine} commands @dfn{authenticate} the code retrieved from channels: they make sure each commit that is fetched is signed by an authorized developer. The goal is to protect from unauthorized modifications to the channel that would lead users to run malicious code. As a user, you must provide a @dfn{channel introduction} in your channels file so that Guix knows how to authenticate its first commit. A channel specification, including its introduction, looks something along these lines: @lisp (channel (name 'some-channel) (url "https://example.org/some-channel.git") (introduction (make-channel-introduction "6f0d8cc0d88abb59c324b2990bfee2876016bb86" (openpgp-fingerprint "CABB A931 C0FF EEC6 900D 0CFB 090B 1199 3D9A EBB5")))) @end lisp The specification above shows the name and URL of the channel. The call to @code{make-channel-introduction} above specifies that authentication of this channel starts at commit @code{6f0d8cc@dots{}}, which is signed by the OpenPGP key with fingerprint @code{CABB A931@dots{}}. For the main channel, called @code{guix}, you automatically get that information from your Guix installation. For other channels, include the channel introduction provided by the channel authors in your @file{channels.scm} file. Make sure you retrieve the channel introduction from a trusted source since that is the root of your trust. If you're curious about the authentication mechanics, read on! @node Creating a Channel @section Creating a Channel @cindex personal packages (channels) @cindex channels, for personal packages Let's say you have a bunch of custom package variants or personal packages that you think would make little sense to contribute to the Guix project, but would like to have these packages transparently available to you at the command line. You would first write modules containing those package definitions (@pxref{Package Modules}), maintain them in a Git repository, and then you and anyone else can use it as an additional channel to get packages from. Neat, no? @c What follows stems from discussions at @c as well as @c earlier discussions on guix-devel@gnu.org. @quotation Warning Before you, dear user, shout---``woow this is @emph{soooo coool}!''---and publish your personal channel to the world, we would like to share a few words of caution: @itemize @item Before publishing a channel, please consider contributing your package definitions to Guix proper (@pxref{Contributing}). Guix as a project is open to free software of all sorts, and packages in Guix proper are readily available to all Guix users and benefit from the project's quality assurance process. @item When you maintain package definitions outside Guix, we, Guix developers, consider that @emph{the compatibility burden is on you}. Remember that package modules and package definitions are just Scheme code that uses various programming interfaces (APIs). We want to remain free to change these APIs to keep improving Guix, possibly in ways that break your channel. We never change APIs gratuitously, but we will @emph{not} commit to freezing APIs either. @item Corollary: if you're using an external channel and that channel breaks, please @emph{report the issue to the channel authors}, not to the Guix project. @end itemize You've been warned! Having said this, we believe external channels are a practical way to exert your freedom to augment Guix' package collection and to share your improvements, which are basic tenets of @uref{https://www.gnu.org/philosophy/free-sw.html, free software}. Please email us at @email{guix-devel@@gnu.org} if you'd like to discuss this. @end quotation To create a channel, create a Git repository containing your own package modules and make it available. The repository can contain anything, but a useful channel will contain Guile modules that export packages. Once you start using a channel, Guix will behave as if the root directory of that channel's Git repository has been added to the Guile load path (@pxref{Load Paths,,, guile, GNU Guile Reference Manual}). For example, if your channel contains a file at @file{my-packages/my-tools.scm} that defines a Guile module, then the module will be available under the name @code{(my-packages my-tools)}, and you will be able to use it like any other module (@pxref{Modules,,, guile, GNU Guile Reference Manual}). As a channel author, consider bundling authentication material with your channel so that users can authenticate it. @xref{Channel Authentication}, and @ref{Specifying Channel Authorizations}, for info on how to do it. @node Package Modules in a Sub-directory @section Package Modules in a Sub-directory @cindex subdirectory, channels As a channel author, you may want to keep your channel modules in a sub-directory. If your modules are in the sub-directory @file{guix}, you must add a meta-data file @file{.guix-channel} that contains: @lisp (channel (version 0) (directory "guix")) @end lisp @node Declaring Channel Dependencies @section Declaring Channel Dependencies @cindex dependencies, channels @cindex meta-data, channels Channel authors may decide to augment a package collection provided by other channels. They can declare their channel to be dependent on other channels in a meta-data file @file{.guix-channel}, which is to be placed in the root of the channel repository. The meta-data file should contain a simple S-expression like this: @lisp (channel (version 0) (dependencies (channel (name 'some-collection) (url "https://example.org/first-collection.git") ;; The 'introduction' bit below is optional: you would ;; provide it for dependencies that can be authenticated. (introduction (channel-introduction (version 0) (commit "a8883b58dc82e167c96506cf05095f37c2c2c6cd") (signer "CABB A931 C0FF EEC6 900D 0CFB 090B 1199 3D9A EBB5")))) (channel (name 'some-other-collection) (url "https://example.org/second-collection.git") (branch "testing")))) @end lisp In the above example this channel is declared to depend on two other channels, which will both be fetched automatically. The modules provided by the channel will be compiled in an environment where the modules of all these declared channels are available. For the sake of reliability and maintainability, you should avoid dependencies on channels that you don't control, and you should aim to keep the number of dependencies to a minimum. @node Specifying Channel Authorizations @section Specifying Channel Authorizations @cindex channel authorizations @anchor{channel-authorizations} As we saw above, Guix ensures the source code it pulls from channels comes from authorized developers. As a channel author, you need to specify the list of authorized developers in the @file{.guix-authorizations} file in the channel's Git repository. The authentication rule is simple: each commit must be signed by a key listed in the @file{.guix-authorizations} file of its parent commit(s)@footnote{Git commits form a @dfn{directed acyclic graph} (DAG). Each commit can have zero or more parents; ``regular'' commits have one parent and merge commits have two parent commits. Read @uref{https://eagain.net/articles/git-for-computer-scientists/, @i{Git for Computer Scientists}} for a great overview.} The @file{.guix-authorizations} file looks like this: @lisp ;; Example '.guix-authorizations' file. (authorizations (version 0) ;current file format version (("AD17 A21E F8AE D8F1 CC02 DBD9 F8AE D8F1 765C 61E3" (name "alice")) ("2A39 3FFF 68F4 EF7A 3D29 12AF 68F4 EF7A 22FB B2D5" (name "bob")) ("CABB A931 C0FF EEC6 900D 0CFB 090B 1199 3D9A EBB5" (name "charlie")))) @end lisp Each fingerprint is followed by optional key/value pairs, as in the example above. Currently these key/value pairs are ignored. This authentication rule creates a chicken-and-egg issue: how do we authenticate the first commit? Related to that: how do we deal with channels whose repository history contains unsigned commits and lack @file{.guix-authorizations}? And how do we fork existing channels? @cindex channel introduction Channel introductions answer these questions by describing the first commit of a channel that should be authenticated. The first time a channel is fetched with @command{guix pull} or @command{guix time-machine}, the command looks up the introductory commit and verifies that it is signed by the specified OpenPGP key. From then on, it authenticates commits according to the rule above. Additionally, your channel must provide all the OpenPGP keys that were ever mentioned in @file{.guix-authorizations}, stored as @file{.key} files, which can be either binary or ``ASCII-armored''. By default, those @file{.key} files are searched for in the branch named @code{keyring} but you can specify a different branch name in @code{.guix-channel} like so: @lisp (channel (version 0) (keyring-reference "my-keyring-branch")) @end lisp To summarize, as the author of a channel, there are three things you have to do to allow users to authenticate your code: @enumerate @item Export the OpenPGP keys of past and present committers with @command{gpg --export} and store them in @file{.key} files, by default in a branch named @code{keyring} (we recommend making it an @dfn{orphan branch}). @item Introduce an initial @file{.guix-authorizations} in the channel's repository. Do that in a signed commit (@pxref{Commit Access}, for information on how to sign Git commits.) @item Advertise the channel introduction, for instance on your channel's web page. The channel introduction, as we saw above, is the commit/key pair---i.e., the commit that introduced @file{.guix-authorizations}, and the fingerprint of the OpenPGP used to sign it. @end enumerate Before pushing to your public Git repository, you can run @command{guix git-authenticate} to verify that you did sign all the commits you are about to push with an authorized key: @example guix git authenticate @var{commit} @var{signer} @end example @noindent where @var{commit} and @var{signer} are your channel introduction. @xref{Invoking guix git authenticate}, for details. Publishing a signed channel requires discipline: any mistake, such as an unsigned commit or a commit signed by an unauthorized key, will prevent users from pulling from your channel---well, that's the whole point of authentication! Pay attention to merges in particular: merge commits are considered authentic if and only if they are signed by a key present in the @file{.guix-authorizations} file of @emph{both} branches. @node Primary URL @section Primary URL @cindex primary URL, channels Channel authors can indicate the primary URL of their channel's Git repository in the @file{.guix-channel} file, like so: @lisp (channel (version 0) (url "https://example.org/guix.git")) @end lisp This allows @command{guix pull} to determine whether it is pulling code from a mirror of the channel; when that is the case, it warns the user that the mirror might be stale and displays the primary URL. That way, users cannot be tricked into fetching code from a stale mirror that does not receive security updates. This feature only makes sense for authenticated repositories, such as the official @code{guix} channel, for which @command{guix pull} ensures the code it fetches is authentic. @node Writing Channel News @section Writing Channel News @cindex news, for channels Channel authors may occasionally want to communicate to their users information about important changes in the channel. You'd send them all an email, but that's not convenient. Instead, channels can provide a @dfn{news file}; when the channel users run @command{guix pull}, that news file is automatically read and @command{guix pull --news} can display the announcements that correspond to the new commits that have been pulled, if any. To do that, channel authors must first declare the name of the news file in their @file{.guix-channel} file: @lisp (channel (version 0) (news-file "etc/news.txt")) @end lisp The news file itself, @file{etc/news.txt} in this example, must look something like this: @lisp (channel-news (version 0) (entry (tag "the-bug-fix") (title (en "Fixed terrible bug") (fr "Oh la la")) (body (en "@@emph@{Good news@}! It's fixed!") (eo "Certe ĝi pli bone funkcias nun!"))) (entry (commit "bdcabe815cd28144a2d2b4bc3c5057b051fa9906") (title (en "Added a great package") (ca "Què vol dir guix?")) (body (en "Don't miss the @@code@{hello@} package!")))) @end lisp While the news file is using the Scheme syntax, avoid naming it with a @file{.scm} extension or else it will get picked up when building the channel and yield an error since it is not a valid module. Alternatively, you can move the channel module to a subdirectory and store the news file in another directory. The file consists of a list of @dfn{news entries}. Each entry is associated with a commit or tag: it describes changes made in this commit, possibly in preceding commits as well. Users see entries only the first time they obtain the commit the entry refers to. The @code{title} field should be a one-line summary while @code{body} can be arbitrarily long, and both can contain Texinfo markup (@pxref{Overview,,, texinfo, GNU Texinfo}). Both the title and body are a list of language tag/message tuples, which allows @command{guix pull} to display news in the language that corresponds to the user's locale. If you want to translate news using a gettext-based workflow, you can extract translatable strings with @command{xgettext} (@pxref{xgettext Invocation,,, gettext, GNU Gettext Utilities}). For example, assuming you write news entries in English first, the command below creates a PO file containing the strings to translate: @example xgettext -o news.po -l scheme -ken etc/news.txt @end example To sum up, yes, you could use your channel as a blog. But beware, this is @emph{not quite} what your users might expect. @c ********************************************************************* @node Development @chapter Development @cindex software development If you are a software developer, Guix provides tools that you should find helpful---independently of the language you're developing in. This is what this chapter is about. The @command{guix environment} command provides a convenient way to set up @dfn{development environments} containing all the dependencies and tools necessary to work on the software package of your choice. The @command{guix pack} command allows you to create @dfn{application bundles} that can be easily distributed to users who do not run Guix. @menu * Invoking guix environment:: Setting up development environments. * Invoking guix pack:: Creating software bundles. * The GCC toolchain:: Working with languages supported by GCC. * Invoking guix git authenticate:: Authenticating Git repositories. @end menu @node Invoking guix environment @section Invoking @command{guix environment} @cindex reproducible build environments @cindex development environments @cindex @command{guix environment} @cindex environment, package build environment The purpose of @command{guix environment} is to assist hackers in creating reproducible development environments without polluting their package profile. The @command{guix environment} tool takes one or more packages, builds all of their inputs, and creates a shell environment to use them. The general syntax is: @example guix environment @var{options} @var{package}@dots{} @end example The following example spawns a new shell set up for the development of GNU@tie{}Guile: @example guix environment guile @end example If the needed dependencies are not built yet, @command{guix environment} automatically builds them. The environment of the new shell is an augmented version of the environment that @command{guix environment} was run in. It contains the necessary search paths for building the given package added to the existing environment variables. To create a ``pure'' environment, in which the original environment variables have been unset, use the @option{--pure} option@footnote{Users sometimes wrongfully augment environment variables such as @env{PATH} in their @file{~/.bashrc} file. As a consequence, when @command{guix environment} launches it, Bash may read @file{~/.bashrc}, thereby introducing ``impurities'' in these environment variables. It is an error to define such environment variables in @file{.bashrc}; instead, they should be defined in @file{.bash_profile}, which is sourced only by log-in shells. @xref{Bash Startup Files,,, bash, The GNU Bash Reference Manual}, for details on Bash start-up files.}. @vindex GUIX_ENVIRONMENT @command{guix environment} defines the @env{GUIX_ENVIRONMENT} variable in the shell it spawns; its value is the file name of the profile of this environment. This allows users to, say, define a specific prompt for development environments in their @file{.bashrc} (@pxref{Bash Startup Files,,, bash, The GNU Bash Reference Manual}): @example if [ -n "$GUIX_ENVIRONMENT" ] then export PS1="\u@@\h \w [dev]\$ " fi @end example @noindent ...@: or to browse the profile: @example $ ls "$GUIX_ENVIRONMENT/bin" @end example Additionally, more than one package may be specified, in which case the union of the inputs for the given packages are used. For example, the command below spawns a shell where all of the dependencies of both Guile and Emacs are available: @example guix environment guile emacs @end example Sometimes an interactive shell session is not desired. An arbitrary command may be invoked by placing the @code{--} token to separate the command from the rest of the arguments: @example guix environment guile -- make -j4 @end example In other situations, it is more convenient to specify the list of packages needed in the environment. For example, the following command runs @command{python} from an environment containing Python@tie{}2.7 and NumPy: @example guix environment --ad-hoc python2-numpy python-2.7 -- python @end example Furthermore, one might want the dependencies of a package and also some additional packages that are not build-time or runtime dependencies, but are useful when developing nonetheless. Because of this, the @option{--ad-hoc} flag is positional. Packages appearing before @option{--ad-hoc} are interpreted as packages whose dependencies will be added to the environment. Packages appearing after are interpreted as packages that will be added to the environment directly. For example, the following command creates a Guix development environment that additionally includes Git and strace: @example guix environment --pure guix --ad-hoc git strace @end example @cindex container Sometimes it is desirable to isolate the environment as much as possible, for maximal purity and reproducibility. In particular, when using Guix on a host distro that is not Guix System, it is desirable to prevent access to @file{/usr/bin} and other system-wide resources from the development environment. For example, the following command spawns a Guile REPL in a ``container'' where only the store and the current working directory are mounted: @example guix environment --ad-hoc --container guile -- guile @end example @quotation Note The @option{--container} option requires Linux-libre 3.19 or newer. @end quotation @cindex certificates Another typical use case for containers is to run security-sensitive applications such as a web browser. To run Eolie, we must expose and share some files and directories; we include @code{nss-certs} and expose @file{/etc/ssl/certs/} for HTTPS authentication; finally we preserve the @env{DISPLAY} environment variable since containerized graphical applications won't display without it. @example guix environment --preserve='^DISPLAY$' --container --network \ --expose=/etc/machine-id \ --expose=/etc/ssl/certs/ \ --share=$HOME/.local/share/eolie/=$HOME/.local/share/eolie/ \ --ad-hoc eolie nss-certs dbus -- eolie @end example The available options are summarized below. @table @code @item --root=@var{file} @itemx -r @var{file} @cindex persistent environment @cindex garbage collector root, for environments Make @var{file} a symlink to the profile for this environment, and register it as a garbage collector root. This is useful if you want to protect your environment from garbage collection, to make it ``persistent''. When this option is omitted, the environment is protected from garbage collection only for the duration of the @command{guix environment} session. This means that next time you recreate the same environment, you could have to rebuild or re-download packages. @xref{Invoking guix gc}, for more on GC roots. @item --expression=@var{expr} @itemx -e @var{expr} Create an environment for the package or list of packages that @var{expr} evaluates to. For example, running: @example guix environment -e '(@@ (gnu packages maths) petsc-openmpi)' @end example starts a shell with the environment for this specific variant of the PETSc package. Running: @example guix environment --ad-hoc -e '(@@ (gnu) %base-packages)' @end example starts a shell with all the base system packages available. The above commands only use the default output of the given packages. To select other outputs, two element tuples can be specified: @example guix environment --ad-hoc -e '(list (@@ (gnu packages bash) bash) "include")' @end example @item --load=@var{file} @itemx -l @var{file} Create an environment for the package or list of packages that the code within @var{file} evaluates to. As an example, @var{file} might contain a definition like this (@pxref{Defining Packages}): @lisp @verbatiminclude environment-gdb.scm @end lisp @item --manifest=@var{file} @itemx -m @var{file} Create an environment for the packages contained in the manifest object returned by the Scheme code in @var{file}. This option can be repeated several times, in which case the manifests are concatenated. This is similar to the same-named option in @command{guix package} (@pxref{profile-manifest, @option{--manifest}}) and uses the same manifest files. @item --ad-hoc Include all specified packages in the resulting environment, as if an @i{ad hoc} package were defined with them as inputs. This option is useful for quickly creating an environment without having to write a package expression to contain the desired inputs. For instance, the command: @example guix environment --ad-hoc guile guile-sdl -- guile @end example runs @command{guile} in an environment where Guile and Guile-SDL are available. Note that this example implicitly asks for the default output of @code{guile} and @code{guile-sdl}, but it is possible to ask for a specific output---e.g., @code{glib:bin} asks for the @code{bin} output of @code{glib} (@pxref{Packages with Multiple Outputs}). This option may be composed with the default behavior of @command{guix environment}. Packages appearing before @option{--ad-hoc} are interpreted as packages whose dependencies will be added to the environment, the default behavior. Packages appearing after are interpreted as packages that will be added to the environment directly. @item --pure Unset existing environment variables when building the new environment, except those specified with @option{--preserve} (see below). This has the effect of creating an environment in which search paths only contain package inputs. @item --preserve=@var{regexp} @itemx -E @var{regexp} When used alongside @option{--pure}, preserve the environment variables matching @var{regexp}---in other words, put them on a ``white list'' of environment variables that must be preserved. This option can be repeated several times. @example guix environment --pure --preserve=^SLURM --ad-hoc openmpi @dots{} \ -- mpirun @dots{} @end example This example runs @command{mpirun} in a context where the only environment variables defined are @env{PATH}, environment variables whose name starts with @samp{SLURM}, as well as the usual ``precious'' variables (@env{HOME}, @env{USER}, etc.). @item --search-paths Display the environment variable definitions that make up the environment. @item --system=@var{system} @itemx -s @var{system} Attempt to build for @var{system}---e.g., @code{i686-linux}. @item --container @itemx -C @cindex container Run @var{command} within an isolated container. The current working directory outside the container is mapped inside the container. Additionally, unless overridden with @option{--user}, a dummy home directory is created that matches the current user's home directory, and @file{/etc/passwd} is configured accordingly. The spawned process runs as the current user outside the container. Inside the container, it has the same UID and GID as the current user, unless @option{--user} is passed (see below). @item --network @itemx -N For containers, share the network namespace with the host system. Containers created without this flag only have access to the loopback device. @item --link-profile @itemx -P For containers, link the environment profile to @file{~/.guix-profile} within the container and set @code{GUIX_ENVIRONMENT} to that. This is equivalent to making @file{~/.guix-profile} a symlink to the actual profile within the container. Linking will fail and abort the environment if the directory already exists, which will certainly be the case if @command{guix environment} was invoked in the user's home directory. Certain packages are configured to look in @file{~/.guix-profile} for configuration files and data;@footnote{For example, the @code{fontconfig} package inspects @file{~/.guix-profile/share/fonts} for additional fonts.} @option{--link-profile} allows these programs to behave as expected within the environment. @item --user=@var{user} @itemx -u @var{user} For containers, use the username @var{user} in place of the current user. The generated @file{/etc/passwd} entry within the container will contain the name @var{user}, the home directory will be @file{/home/@var{user}}, and no user GECOS data will be copied. Furthermore, the UID and GID inside the container are 1000. @var{user} need not exist on the system. Additionally, any shared or exposed path (see @option{--share} and @option{--expose} respectively) whose target is within the current user's home directory will be remapped relative to @file{/home/USER}; this includes the automatic mapping of the current working directory. @example # will expose paths as /home/foo/wd, /home/foo/test, and /home/foo/target cd $HOME/wd guix environment --container --user=foo \ --expose=$HOME/test \ --expose=/tmp/target=$HOME/target @end example While this will limit the leaking of user identity through home paths and each of the user fields, this is only one useful component of a broader privacy/anonymity solution---not one in and of itself. @item --no-cwd For containers, the default behavior is to share the current working directory with the isolated container and immediately change to that directory within the container. If this is undesirable, @option{--no-cwd} will cause the current working directory to @emph{not} be automatically shared and will change to the user's home directory within the container instead. See also @option{--user}. @item --expose=@var{source}[=@var{target}] @itemx --share=@var{source}[=@var{target}] For containers, @option{--expose} (resp. @option{--share}) exposes the file system @var{source} from the host system as the read-only (resp. writable) file system @var{target} within the container. If @var{target} is not specified, @var{source} is used as the target mount point in the container. The example below spawns a Guile REPL in a container in which the user's home directory is accessible read-only via the @file{/exchange} directory: @example guix environment --container --expose=$HOME=/exchange --ad-hoc guile -- guile @end example @end table @command{guix environment} also supports all of the common build options that @command{guix build} supports (@pxref{Common Build Options}) as well as package transformation options (@pxref{Package Transformation Options}). @node Invoking guix pack @section Invoking @command{guix pack} Occasionally you want to pass software to people who are not (yet!) lucky enough to be using Guix. You'd tell them to run @command{guix package -i @var{something}}, but that's not possible in this case. This is where @command{guix pack} comes in. @quotation Note If you are looking for ways to exchange binaries among machines that already run Guix, @pxref{Invoking guix copy}, @ref{Invoking guix publish}, and @ref{Invoking guix archive}. @end quotation @cindex pack @cindex bundle @cindex application bundle @cindex software bundle The @command{guix pack} command creates a shrink-wrapped @dfn{pack} or @dfn{software bundle}: it creates a tarball or some other archive containing the binaries of the software you're interested in, and all its dependencies. The resulting archive can be used on any machine that does not have Guix, and people can run the exact same binaries as those you have with Guix. The pack itself is created in a bit-reproducible fashion, so anyone can verify that it really contains the build results that you pretend to be shipping. For example, to create a bundle containing Guile, Emacs, Geiser, and all their dependencies, you can run: @example $ guix pack guile emacs geiser @dots{} /gnu/store/@dots{}-pack.tar.gz @end example The result here is a tarball containing a @file{/gnu/store} directory with all the relevant packages. The resulting tarball contains a @dfn{profile} with the three packages of interest; the profile is the same as would be created by @command{guix package -i}. It is this mechanism that is used to create Guix's own standalone binary tarball (@pxref{Binary Installation}). Users of this pack would have to run @file{/gnu/store/@dots{}-profile/bin/guile} to run Guile, which you may find inconvenient. To work around it, you can create, say, a @file{/opt/gnu/bin} symlink to the profile: @example guix pack -S /opt/gnu/bin=bin guile emacs geiser @end example @noindent That way, users can happily type @file{/opt/gnu/bin/guile} and enjoy. @cindex relocatable binaries, with @command{guix pack} What if the recipient of your pack does not have root privileges on their machine, and thus cannot unpack it in the root file system? In that case, you will want to use the @option{--relocatable} option (see below). This option produces @dfn{relocatable binaries}, meaning they they can be placed anywhere in the file system hierarchy: in the example above, users can unpack your tarball in their home directory and directly run @file{./opt/gnu/bin/guile}. @cindex Docker, build an image with guix pack Alternatively, you can produce a pack in the Docker image format using the following command: @example guix pack -f docker -S /bin=bin guile guile-readline @end example @noindent The result is a tarball that can be passed to the @command{docker load} command, followed by @code{docker run}: @example docker load < @var{file} docker run -ti guile-guile-readline /bin/guile @end example @noindent where @var{file} is the image returned by @var{guix pack}, and @code{guile-guile-readline} is its ``image tag''. See the @uref{https://docs.docker.com/engine/reference/commandline/load/, Docker documentation} for more information. @cindex Singularity, build an image with guix pack @cindex SquashFS, build an image with guix pack Yet another option is to produce a SquashFS image with the following command: @example guix pack -f squashfs bash guile emacs geiser @end example @noindent The result is a SquashFS file system image that can either be mounted or directly be used as a file system container image with the @uref{https://www.sylabs.io/docs/, Singularity container execution environment}, using commands like @command{singularity shell} or @command{singularity exec}. Several command-line options allow you to customize your pack: @table @code @item --format=@var{format} @itemx -f @var{format} Produce a pack in the given @var{format}. The available formats are: @table @code @item tarball This is the default format. It produces a tarball containing all the specified binaries and symlinks. @item docker This produces a tarball that follows the @uref{https://github.com/docker/docker/blob/master/image/spec/v1.2.md, Docker Image Specification}. The ``repository name'' as it appears in the output of the @command{docker images} command is computed from package names passed on the command line or in the manifest file. @item squashfs This produces a SquashFS image containing all the specified binaries and symlinks, as well as empty mount points for virtual file systems like procfs. @quotation Note Singularity @emph{requires} you to provide @file{/bin/sh} in the image. For that reason, @command{guix pack -f squashfs} always implies @code{-S /bin=bin}. Thus, your @command{guix pack} invocation must always start with something like: @example guix pack -f squashfs bash @dots{} @end example If you forget the @code{bash} (or similar) package, @command{singularity run} and @command{singularity exec} will fail with an unhelpful ``no such file or directory'' message. @end quotation @end table @cindex relocatable binaries @item --relocatable @itemx -R Produce @dfn{relocatable binaries}---i.e., binaries that can be placed anywhere in the file system hierarchy and run from there. When this option is passed once, the resulting binaries require support for @dfn{user namespaces} in the kernel Linux; when passed @emph{twice}@footnote{Here's a trick to memorize it: @code{-RR}, which adds PRoot support, can be thought of as the abbreviation of ``Really Relocatable''. Neat, isn't it?}, relocatable binaries fall to back to other techniques if user namespaces are unavailable, and essentially work anywhere---see below for the implications. For example, if you create a pack containing Bash with: @example guix pack -RR -S /mybin=bin bash @end example @noindent ...@: you can copy that pack to a machine that lacks Guix, and from your home directory as a normal user, run: @example tar xf pack.tar.gz ./mybin/sh @end example @noindent In that shell, if you type @code{ls /gnu/store}, you'll notice that @file{/gnu/store} shows up and contains all the dependencies of @code{bash}, even though the machine actually lacks @file{/gnu/store} altogether! That is probably the simplest way to deploy Guix-built software on a non-Guix machine. @quotation Note By default, relocatable binaries rely on the @dfn{user namespace} feature of the kernel Linux, which allows unprivileged users to mount or change root. Old versions of Linux did not support it, and some GNU/Linux distributions turn it off. To produce relocatable binaries that work even in the absence of user namespaces, pass @option{--relocatable} or @option{-R} @emph{twice}. In that case, binaries will try user namespace support and fall back to another @dfn{execution engine} if user namespaces are not supported. The following execution engines are supported: @table @code @item default Try user namespaces and fall back to PRoot if user namespaces are not supported (see below). @item performance Try user namespaces and fall back to Fakechroot if user namespaces are not supported (see below). @item userns Run the program through user namespaces and abort if they are not supported. @item proot Run through PRoot. The @uref{https://proot-me.github.io/, PRoot} program provides the necessary support for file system virtualization. It achieves that by using the @code{ptrace} system call on the running program. This approach has the advantage to work without requiring special kernel support, but it incurs run-time overhead every time a system call is made. @item fakechroot Run through Fakechroot. @uref{https://github.com/dex4er/fakechroot/, Fakechroot} virtualizes file system accesses by intercepting calls to C library functions such as @code{open}, @code{stat}, @code{exec}, and so on. Unlike PRoot, it incurs very little overhead. However, it does not always work: for example, some file system accesses made from within the C library are not intercepted, and file system accesses made @i{via} direct syscalls are not intercepted either, leading to erratic behavior. @end table @vindex GUIX_EXECUTION_ENGINE When running a wrapped program, you can explicitly request one of the execution engines listed above by setting the @env{GUIX_EXECUTION_ENGINE} environment variable accordingly. @end quotation @cindex entry point, for Docker images @item --entry-point=@var{command} Use @var{command} as the @dfn{entry point} of the resulting pack, if the pack format supports it---currently @code{docker} and @code{squashfs} (Singularity) support it. @var{command} must be relative to the profile contained in the pack. The entry point specifies the command that tools like @code{docker run} or @code{singularity run} automatically start by default. For example, you can do: @example guix pack -f docker --entry-point=bin/guile guile @end example The resulting pack can easily be loaded and @code{docker run} with no extra arguments will spawn @code{bin/guile}: @example docker load -i pack.tar.gz docker run @var{image-id} @end example @item --expression=@var{expr} @itemx -e @var{expr} Consider the package @var{expr} evaluates to. This has the same purpose as the same-named option in @command{guix build} (@pxref{Additional Build Options, @option{--expression} in @command{guix build}}). @item --manifest=@var{file} @itemx -m @var{file} Use the packages contained in the manifest object returned by the Scheme code in @var{file}. This option can be repeated several times, in which case the manifests are concatenated. This has a similar purpose as the same-named option in @command{guix package} (@pxref{profile-manifest, @option{--manifest}}) and uses the same manifest files. It allows you to define a collection of packages once and use it both for creating profiles and for creating archives for use on machines that do not have Guix installed. Note that you can specify @emph{either} a manifest file @emph{or} a list of packages, but not both. @item --system=@var{system} @itemx -s @var{system} Attempt to build for @var{system}---e.g., @code{i686-linux}---instead of the system type of the build host. @item --target=@var{triplet} @cindex cross-compilation Cross-build for @var{triplet}, which must be a valid GNU triplet, such as @code{"aarch64-linux-gnu"} (@pxref{Specifying target triplets, GNU configuration triplets,, autoconf, Autoconf}). @item --compression=@var{tool} @itemx -C @var{tool} Compress the resulting tarball using @var{tool}---one of @code{gzip}, @code{zstd}, @code{bzip2}, @code{xz}, @code{lzip}, or @code{none} for no compression. @item --symlink=@var{spec} @itemx -S @var{spec} Add the symlinks specified by @var{spec} to the pack. This option can appear several times. @var{spec} has the form @code{@var{source}=@var{target}}, where @var{source} is the symlink that will be created and @var{target} is the symlink target. For instance, @code{-S /opt/gnu/bin=bin} creates a @file{/opt/gnu/bin} symlink pointing to the @file{bin} sub-directory of the profile. @item --save-provenance Save provenance information for the packages passed on the command line. Provenance information includes the URL and commit of the channels in use (@pxref{Channels}). Provenance information is saved in the @file{/gnu/store/@dots{}-profile/manifest} file in the pack, along with the usual package metadata---the name and version of each package, their propagated inputs, and so on. It is useful information to the recipient of the pack, who then knows how the pack was (supposedly) obtained. This option is not enabled by default because, like timestamps, provenance information contributes nothing to the build process. In other words, there is an infinity of channel URLs and commit IDs that can lead to the same pack. Recording such ``silent'' metadata in the output thus potentially breaks the source-to-binary bitwise reproducibility property. @item --root=@var{file} @itemx -r @var{file} @cindex garbage collector root, for packs Make @var{file} a symlink to the resulting pack, and register it as a garbage collector root. @item --localstatedir @itemx --profile-name=@var{name} Include the ``local state directory'', @file{/var/guix}, in the resulting pack, and notably the @file{/var/guix/profiles/per-user/root/@var{name}} profile---by default @var{name} is @code{guix-profile}, which corresponds to @file{~root/.guix-profile}. @file{/var/guix} contains the store database (@pxref{The Store}) as well as garbage-collector roots (@pxref{Invoking guix gc}). Providing it in the pack means that the store is ``complete'' and manageable by Guix; not providing it pack means that the store is ``dead'': items cannot be added to it or removed from it after extraction of the pack. One use case for this is the Guix self-contained binary tarball (@pxref{Binary Installation}). @item --derivation @itemx -d Print the name of the derivation that builds the pack. @item --bootstrap Use the bootstrap binaries to build the pack. This option is only useful to Guix developers. @end table In addition, @command{guix pack} supports all the common build options (@pxref{Common Build Options}) and all the package transformation options (@pxref{Package Transformation Options}). @node The GCC toolchain @section The GCC toolchain @cindex GCC @cindex ld-wrapper @cindex linker wrapper @cindex toolchain, for C development @cindex toolchain, for Fortran development If you need a complete toolchain for compiling and linking C or C++ source code, use the @code{gcc-toolchain} package. This package provides a complete GCC toolchain for C/C++ development, including GCC itself, the GNU C Library (headers and binaries, plus debugging symbols in the @code{debug} output), Binutils, and a linker wrapper. The wrapper's purpose is to inspect the @code{-L} and @code{-l} switches passed to the linker, add corresponding @code{-rpath} arguments, and invoke the actual linker with this new set of arguments. You can instruct the wrapper to refuse to link against libraries not in the store by setting the @env{GUIX_LD_WRAPPER_ALLOW_IMPURITIES} environment variable to @code{no}. The package @code{gfortran-toolchain} provides a complete GCC toolchain for Fortran development. For other languages, please use @samp{guix search gcc toolchain} (@pxref{guix-search,, Invoking guix package}). @node Invoking guix git authenticate @section Invoking @command{guix git authenticate} The @command{guix git authenticate} command authenticates a Git checkout following the same rule as for channels (@pxref{channel-authentication, channel authentication}). That is, starting from a given commit, it ensures that all subsequent commits are signed by an OpenPGP key whose fingerprint appears in the @file{.guix-authorizations} file of its parent commit(s). You will find this command useful if you maintain a channel. But in fact, this authentication mechanism is useful in a broader context, so you might want to use it for Git repositories that have nothing to do with Guix. The general syntax is: @example guix git authenticate @var{commit} @var{signer} [@var{options}@dots{}] @end example By default, this command authenticates the Git checkout in the current directory; it outputs nothing and exits with exit code zero on success and non-zero on failure. @var{commit} above denotes the first commit where authentication takes place, and @var{signer} is the OpenPGP fingerprint of public key used to sign @var{commit}. Together, they form a ``channel introduction'' (@pxref{channel-authentication, channel introduction}). The options below allow you to fine-tune the process. @table @code @item --repository=@var{directory} @itemx -r @var{directory} Open the Git repository in @var{directory} instead of the current directory. @item --keyring=@var{reference} @itemx -k @var{reference} Load OpenPGP keyring from @var{reference}, the reference of a branch such as @code{origin/keyring} or @code{my-keyring}. The branch must contain OpenPGP public keys in @file{.key} files, either in binary form or ``ASCII-armored''. By default the keyring is loaded from the branch named @code{keyring}. @item --stats Display commit signing statistics upon completion. @item --cache-key=@var{key} Previously-authenticated commits are cached in a file under @file{~/.cache/guix/authentication}. This option forces the cache to be stored in file @var{key} in that directory. @item --historical-authorizations=@var{file} By default, any commit whose parent commit(s) lack the @file{.guix-authorizations} file is considered inauthentic. In contrast, this option considers the authorizations in @var{file} for any commit that lacks @file{.guix-authorizations}. The format of @var{file} is the same as that of @file{.guix-authorizations} (@pxref{channel-authorizations, @file{.guix-authorizations} format}). @end table @c ********************************************************************* @node Programming Interface @chapter Programming Interface GNU Guix provides several Scheme programming interfaces (APIs) to define, build, and query packages. The first interface allows users to write high-level package definitions. These definitions refer to familiar packaging concepts, such as the name and version of a package, its build system, and its dependencies. These definitions can then be turned into concrete build actions. Build actions are performed by the Guix daemon, on behalf of users. In a standard setup, the daemon has write access to the store---the @file{/gnu/store} directory---whereas users do not. The recommended setup also has the daemon perform builds in chroots, under specific build users, to minimize interference with the rest of the system. @cindex derivation Lower-level APIs are available to interact with the daemon and the store. To instruct the daemon to perform a build action, users actually provide it with a @dfn{derivation}. A derivation is a low-level representation of the build actions to be taken, and the environment in which they should occur---derivations are to package definitions what assembly is to C programs. The term ``derivation'' comes from the fact that build results @emph{derive} from them. This chapter describes all these APIs in turn, starting from high-level package definitions. @menu * Package Modules:: Packages from the programmer's viewpoint. * Defining Packages:: Defining new packages. * Defining Package Variants:: Customizing packages. * Build Systems:: Specifying how packages are built. * Build Phases:: Phases of the build process of a package. * Build Utilities:: Helpers for your package definitions and more. * The Store:: Manipulating the package store. * Derivations:: Low-level interface to package derivations. * The Store Monad:: Purely functional interface to the store. * G-Expressions:: Manipulating build expressions. * Invoking guix repl:: Programming Guix in Guile @end menu @node Package Modules @section Package Modules From a programming viewpoint, the package definitions of the GNU distribution are provided by Guile modules in the @code{(gnu packages @dots{})} name space@footnote{Note that packages under the @code{(gnu packages @dots{})} module name space are not necessarily ``GNU packages''. This module naming scheme follows the usual Guile module naming convention: @code{gnu} means that these modules are distributed as part of the GNU system, and @code{packages} identifies modules that define packages.} (@pxref{Modules, Guile modules,, guile, GNU Guile Reference Manual}). For instance, the @code{(gnu packages emacs)} module exports a variable named @code{emacs}, which is bound to a @code{} object (@pxref{Defining Packages}). The @code{(gnu packages @dots{})} module name space is automatically scanned for packages by the command-line tools. For instance, when running @code{guix install emacs}, all the @code{(gnu packages @dots{})} modules are scanned until one that exports a package object whose name is @code{emacs} is found. This package search facility is implemented in the @code{(gnu packages)} module. @cindex customization, of packages @cindex package module search path Users can store package definitions in modules with different names---e.g., @code{(my-packages emacs)}@footnote{Note that the file name and module name must match. For instance, the @code{(my-packages emacs)} module must be stored in a @file{my-packages/emacs.scm} file relative to the load path specified with @option{--load-path} or @env{GUIX_PACKAGE_PATH}. @xref{Modules and the File System,,, guile, GNU Guile Reference Manual}, for details.}. There are two ways to make these package definitions visible to the user interfaces: @enumerate @item By adding the directory containing your package modules to the search path with the @code{-L} flag of @command{guix package} and other commands (@pxref{Common Build Options}), or by setting the @env{GUIX_PACKAGE_PATH} environment variable described below. @item By defining a @dfn{channel} and configuring @command{guix pull} so that it pulls from it. A channel is essentially a Git repository containing package modules. @xref{Channels}, for more information on how to define and use channels. @end enumerate @env{GUIX_PACKAGE_PATH} works similarly to other search path variables: @defvr {Environment Variable} GUIX_PACKAGE_PATH This is a colon-separated list of directories to search for additional package modules. Directories listed in this variable take precedence over the own modules of the distribution. @end defvr The distribution is fully @dfn{bootstrapped} and @dfn{self-contained}: each package is built based solely on other packages in the distribution. The root of this dependency graph is a small set of @dfn{bootstrap binaries}, provided by the @code{(gnu packages bootstrap)} module. For more information on bootstrapping, @pxref{Bootstrapping}. @node Defining Packages @section Defining Packages The high-level interface to package definitions is implemented in the @code{(guix packages)} and @code{(guix build-system)} modules. As an example, the package definition, or @dfn{recipe}, for the GNU Hello package looks like this: @lisp (define-module (gnu packages hello) #:use-module (guix packages) #:use-module (guix download) #:use-module (guix build-system gnu) #:use-module (guix licenses) #:use-module (gnu packages gawk)) (define-public hello (package (name "hello") (version "2.10") (source (origin (method url-fetch) (uri (string-append "mirror://gnu/hello/hello-" version ".tar.gz")) (sha256 (base32 "0ssi1wpaf7plaswqqjwigppsg5fyh99vdlb9kzl7c9lng89ndq1i")))) (build-system gnu-build-system) (arguments '(#:configure-flags '("--enable-silent-rules"))) (inputs `(("gawk" ,gawk))) (synopsis "Hello, GNU world: An example GNU package") (description "Guess what GNU Hello prints!") (home-page "https://www.gnu.org/software/hello/") (license gpl3+))) @end lisp @noindent Without being a Scheme expert, the reader may have guessed the meaning of the various fields here. This expression binds the variable @code{hello} to a @code{} object, which is essentially a record (@pxref{SRFI-9, Scheme records,, guile, GNU Guile Reference Manual}). This package object can be inspected using procedures found in the @code{(guix packages)} module; for instance, @code{(package-name hello)} returns---surprise!---@code{"hello"}. With luck, you may be able to import part or all of the definition of the package you are interested in from another repository, using the @code{guix import} command (@pxref{Invoking guix import}). In the example above, @code{hello} is defined in a module of its own, @code{(gnu packages hello)}. Technically, this is not strictly necessary, but it is convenient to do so: all the packages defined in modules under @code{(gnu packages @dots{})} are automatically known to the command-line tools (@pxref{Package Modules}). There are a few points worth noting in the above package definition: @itemize @item The @code{source} field of the package is an @code{} object (@pxref{origin Reference}, for the complete reference). Here, the @code{url-fetch} method from @code{(guix download)} is used, meaning that the source is a file to be downloaded over FTP or HTTP. The @code{mirror://gnu} prefix instructs @code{url-fetch} to use one of the GNU mirrors defined in @code{(guix download)}. The @code{sha256} field specifies the expected SHA256 hash of the file being downloaded. It is mandatory, and allows Guix to check the integrity of the file. The @code{(base32 @dots{})} form introduces the base32 representation of the hash. You can obtain this information with @code{guix download} (@pxref{Invoking guix download}) and @code{guix hash} (@pxref{Invoking guix hash}). @cindex patches When needed, the @code{origin} form can also have a @code{patches} field listing patches to be applied, and a @code{snippet} field giving a Scheme expression to modify the source code. @item @cindex GNU Build System The @code{build-system} field specifies the procedure to build the package (@pxref{Build Systems}). Here, @code{gnu-build-system} represents the familiar GNU Build System, where packages may be configured, built, and installed with the usual @code{./configure && make && make check && make install} command sequence. When you start packaging non-trivial software, you may need tools to manipulate those build phases, manipulate files, and so on. @xref{Build Utilities}, for more on this. @item The @code{arguments} field specifies options for the build system (@pxref{Build Systems}). Here it is interpreted by @code{gnu-build-system} as a request run @file{configure} with the @option{--enable-silent-rules} flag. @cindex quote @cindex quoting @findex ' @findex quote What about these quote (@code{'}) characters? They are Scheme syntax to introduce a literal list; @code{'} is synonymous with @code{quote}. @xref{Expression Syntax, quoting,, guile, GNU Guile Reference Manual}, for details. Here the value of the @code{arguments} field is a list of arguments passed to the build system down the road, as with @code{apply} (@pxref{Fly Evaluation, @code{apply},, guile, GNU Guile Reference Manual}). The hash-colon (@code{#:}) sequence defines a Scheme @dfn{keyword} (@pxref{Keywords,,, guile, GNU Guile Reference Manual}), and @code{#:configure-flags} is a keyword used to pass a keyword argument to the build system (@pxref{Coding With Keywords,,, guile, GNU Guile Reference Manual}). @item The @code{inputs} field specifies inputs to the build process---i.e., build-time or run-time dependencies of the package. Here, we define an input called @code{"gawk"} whose value is that of the @code{gawk} variable; @code{gawk} is itself bound to a @code{} object. @cindex backquote (quasiquote) @findex ` @findex quasiquote @cindex comma (unquote) @findex , @findex unquote @findex ,@@ @findex unquote-splicing Again, @code{`} (a backquote, synonymous with @code{quasiquote}) allows us to introduce a literal list in the @code{inputs} field, while @code{,} (a comma, synonymous with @code{unquote}) allows us to insert a value in that list (@pxref{Expression Syntax, unquote,, guile, GNU Guile Reference Manual}). Note that GCC, Coreutils, Bash, and other essential tools do not need to be specified as inputs here. Instead, @code{gnu-build-system} takes care of ensuring that they are present (@pxref{Build Systems}). However, any other dependencies need to be specified in the @code{inputs} field. Any dependency not specified here will simply be unavailable to the build process, possibly leading to a build failure. @end itemize @xref{package Reference}, for a full description of possible fields. Once a package definition is in place, the package may actually be built using the @code{guix build} command-line tool (@pxref{Invoking guix build}), troubleshooting any build failures you encounter (@pxref{Debugging Build Failures}). You can easily jump back to the package definition using the @command{guix edit} command (@pxref{Invoking guix edit}). @xref{Packaging Guidelines}, for more information on how to test package definitions, and @ref{Invoking guix lint}, for information on how to check a definition for style conformance. @vindex GUIX_PACKAGE_PATH Lastly, @pxref{Channels}, for information on how to extend the distribution by adding your own package definitions in a ``channel''. Finally, updating the package definition to a new upstream version can be partly automated by the @command{guix refresh} command (@pxref{Invoking guix refresh}). Behind the scenes, a derivation corresponding to the @code{} object is first computed by the @code{package-derivation} procedure. That derivation is stored in a @file{.drv} file under @file{/gnu/store}. The build actions it prescribes may then be realized by using the @code{build-derivations} procedure (@pxref{The Store}). @deffn {Scheme Procedure} package-derivation @var{store} @var{package} [@var{system}] Return the @code{} object of @var{package} for @var{system} (@pxref{Derivations}). @var{package} must be a valid @code{} object, and @var{system} must be a string denoting the target system type---e.g., @code{"x86_64-linux"} for an x86_64 Linux-based GNU system. @var{store} must be a connection to the daemon, which operates on the store (@pxref{The Store}). @end deffn @noindent @cindex cross-compilation Similarly, it is possible to compute a derivation that cross-builds a package for some other system: @deffn {Scheme Procedure} package-cross-derivation @var{store} @ @var{package} @var{target} [@var{system}] Return the @code{} object of @var{package} cross-built from @var{system} to @var{target}. @var{target} must be a valid GNU triplet denoting the target hardware and operating system, such as @code{"aarch64-linux-gnu"} (@pxref{Specifying Target Triplets,,, autoconf, Autoconf}). @end deffn Once you have package definitions, you can easily define @emph{variants} of those packages. @xref{Defining Package Variants}, for more on that. @menu * package Reference:: The package data type. * origin Reference:: The origin data type. @end menu @node package Reference @subsection @code{package} Reference This section summarizes all the options available in @code{package} declarations (@pxref{Defining Packages}). @deftp {Data Type} package This is the data type representing a package recipe. @table @asis @item @code{name} The name of the package, as a string. @item @code{version} The version of the package, as a string. @item @code{source} An object telling how the source code for the package should be acquired. Most of the time, this is an @code{origin} object, which denotes a file fetched from the Internet (@pxref{origin Reference}). It can also be any other ``file-like'' object such as a @code{local-file}, which denotes a file from the local file system (@pxref{G-Expressions, @code{local-file}}). @item @code{build-system} The build system that should be used to build the package (@pxref{Build Systems}). @item @code{arguments} (default: @code{'()}) The arguments that should be passed to the build system. This is a list, typically containing sequential keyword-value pairs. @item @code{inputs} (default: @code{'()}) @itemx @code{native-inputs} (default: @code{'()}) @itemx @code{propagated-inputs} (default: @code{'()}) @cindex inputs, of packages These fields list dependencies of the package. Each one is a list of tuples, where each tuple has a label for the input (a string) as its first element, a package, origin, or derivation as its second element, and optionally the name of the output thereof that should be used, which defaults to @code{"out"} (@pxref{Packages with Multiple Outputs}, for more on package outputs). For example, the list below specifies three inputs: @lisp `(("libffi" ,libffi) ("libunistring" ,libunistring) ("glib:bin" ,glib "bin")) ;the "bin" output of Glib @end lisp @cindex cross compilation, package dependencies The distinction between @code{native-inputs} and @code{inputs} is necessary when considering cross-compilation. When cross-compiling, dependencies listed in @code{inputs} are built for the @emph{target} architecture; conversely, dependencies listed in @code{native-inputs} are built for the architecture of the @emph{build} machine. @code{native-inputs} is typically used to list tools needed at build time, but not at run time, such as Autoconf, Automake, pkg-config, Gettext, or Bison. @command{guix lint} can report likely mistakes in this area (@pxref{Invoking guix lint}). @anchor{package-propagated-inputs} Lastly, @code{propagated-inputs} is similar to @code{inputs}, but the specified packages will be automatically installed to profiles (@pxref{Features, the role of profiles in Guix}) alongside the package they belong to (@pxref{package-cmd-propagated-inputs, @command{guix package}}, for information on how @command{guix package} deals with propagated inputs). For example this is necessary when packaging a C/C++ library that needs headers of another library to compile, or when a pkg-config file refers to another one @i{via} its @code{Requires} field. Another example where @code{propagated-inputs} is useful is for languages that lack a facility to record the run-time search path akin to the @code{RUNPATH} of ELF files; this includes Guile, Python, Perl, and more. When packaging libraries written in those languages, ensure they can find library code they depend on at run time by listing run-time dependencies in @code{propagated-inputs} rather than @code{inputs}. @item @code{outputs} (default: @code{'("out")}) The list of output names of the package. @xref{Packages with Multiple Outputs}, for typical uses of additional outputs. @item @code{native-search-paths} (default: @code{'()}) @itemx @code{search-paths} (default: @code{'()}) A list of @code{search-path-specification} objects describing search-path environment variables honored by the package. @item @code{replacement} (default: @code{#f}) This must be either @code{#f} or a package object that will be used as a @dfn{replacement} for this package. @xref{Security Updates, grafts}, for details. @item @code{synopsis} A one-line description of the package. @item @code{description} A more elaborate description of the package. @item @code{license} @cindex license, of packages The license of the package; a value from @code{(guix licenses)}, or a list of such values. @item @code{home-page} The URL to the home-page of the package, as a string. @item @code{supported-systems} (default: @code{%supported-systems}) The list of systems supported by the package, as strings of the form @code{architecture-kernel}, for example @code{"x86_64-linux"}. @item @code{location} (default: source location of the @code{package} form) The source location of the package. It is useful to override this when inheriting from another package, in which case this field is not automatically corrected. @end table @end deftp @deffn {Scheme Syntax} this-package When used in the @emph{lexical scope} of a package field definition, this identifier resolves to the package being defined. The example below shows how to add a package as a native input of itself when cross-compiling: @lisp (package (name "guile") ;; ... ;; When cross-compiled, Guile, for example, depends on ;; a native version of itself. Add it here. (native-inputs (if (%current-target-system) `(("self" ,this-package)) '()))) @end lisp It is an error to refer to @code{this-package} outside a package definition. @end deffn Because packages are regular Scheme objects that capture a complete dependency graph and associated build procedures, it is often useful to write procedures that take a package and return a modified version thereof according to some parameters. Below are a few examples. @cindex tool chain, choosing a package's tool chain @deffn {Scheme Procedure} package-with-c-toolchain @var{package} @var{toolchain} Return a variant of @var{package} that uses @var{toolchain} instead of the default GNU C/C++ toolchain. @var{toolchain} must be a list of inputs (label/package tuples) providing equivalent functionality, such as the @code{gcc-toolchain} package. The example below returns a variant of the @code{hello} package built with GCC@tie{}10.x and the rest of the GNU tool chain (Binutils and the GNU C Library) instead of the default tool chain: @lisp (let ((toolchain (specification->package "gcc-toolchain@@10"))) (package-with-c-toolchain hello `(("toolchain" ,toolchain)))) @end lisp The build tool chain is part of the @dfn{implicit inputs} of packages---it's usually not listed as part of the various ``inputs'' fields and is instead pulled in by the build system. Consequently, this procedure works by changing the build system of @var{package} so that it pulls in @var{toolchain} instead of the defaults. @ref{Build Systems}, for more on build systems. @end deffn @node origin Reference @subsection @code{origin} Reference This section documents @dfn{origins}. An @code{origin} declaration specifies data that must be ``produced''---downloaded, usually---and whose content hash is known in advance. Origins are primarily used to represent the source code of packages (@pxref{Defining Packages}). For that reason, the @code{origin} form allows you to declare patches to apply to the original source code as well as code snippets to modify it. @deftp {Data Type} origin This is the data type representing a source code origin. @table @asis @item @code{uri} An object containing the URI of the source. The object type depends on the @code{method} (see below). For example, when using the @var{url-fetch} method of @code{(guix download)}, the valid @code{uri} values are: a URL represented as a string, or a list thereof. @cindex fixed-output derivations, for download @item @code{method} A monadic procedure that handles the given URI. The procedure must accept at least three arguments: the value of the @code{uri} field and the hash algorithm and hash value specified by the @code{hash} field. It must return a store item or a derivation in the store monad (@pxref{The Store Monad}); most methods return a fixed-output derivation (@pxref{Derivations}). Commonly used methods include @code{url-fetch}, which fetches data from a URL, and @code{git-fetch}, which fetches data from a Git repository (see below). @item @code{sha256} A bytevector containing the SHA-256 hash of the source. This is equivalent to providing a @code{content-hash} SHA256 object in the @code{hash} field described below. @item @code{hash} The @code{content-hash} object of the source---see below for how to use @code{content-hash}. You can obtain this information using @code{guix download} (@pxref{Invoking guix download}) or @code{guix hash} (@pxref{Invoking guix hash}). @item @code{file-name} (default: @code{#f}) The file name under which the source code should be saved. When this is @code{#f}, a sensible default value will be used in most cases. In case the source is fetched from a URL, the file name from the URL will be used. For version control checkouts, it is recommended to provide the file name explicitly because the default is not very descriptive. @item @code{patches} (default: @code{'()}) A list of file names, origins, or file-like objects (@pxref{G-Expressions, file-like objects}) pointing to patches to be applied to the source. This list of patches must be unconditional. In particular, it cannot depend on the value of @code{%current-system} or @code{%current-target-system}. @item @code{snippet} (default: @code{#f}) A G-expression (@pxref{G-Expressions}) or S-expression that will be run in the source directory. This is a convenient way to modify the source, sometimes more convenient than a patch. @item @code{patch-flags} (default: @code{'("-p1")}) A list of command-line flags that should be passed to the @code{patch} command. @item @code{patch-inputs} (default: @code{#f}) Input packages or derivations to the patching process. When this is @code{#f}, the usual set of inputs necessary for patching are provided, such as GNU@tie{}Patch. @item @code{modules} (default: @code{'()}) A list of Guile modules that should be loaded during the patching process and while running the code in the @code{snippet} field. @item @code{patch-guile} (default: @code{#f}) The Guile package that should be used in the patching process. When this is @code{#f}, a sensible default is used. @end table @end deftp @deftp {Data Type} content-hash @var{value} [@var{algorithm}] Construct a content hash object for the given @var{algorithm}, and with @var{value} as its hash value. When @var{algorithm} is omitted, assume it is @code{sha256}. @var{value} can be a literal string, in which case it is base32-decoded, or it can be a bytevector. The following forms are all equivalent: @lisp (content-hash "05zxkyz9bv3j9h0xyid1rhvh3klhsmrpkf3bcs6frvlgyr2gwilj") (content-hash "05zxkyz9bv3j9h0xyid1rhvh3klhsmrpkf3bcs6frvlgyr2gwilj" sha256) (content-hash (base32 "05zxkyz9bv3j9h0xyid1rhvh3klhsmrpkf3bcs6frvlgyr2gwilj")) (content-hash (base64 "kkb+RPaP7uyMZmu4eXPVkM4BN8yhRd8BTHLslb6f/Rc=") sha256) @end lisp Technically, @code{content-hash} is currently implemented as a macro. It performs sanity checks at macro-expansion time, when possible, such as ensuring that @var{value} has the right size for @var{algorithm}. @end deftp As we have seen above, how exactly the data an origin refers to is retrieved is determined by its @code{method} field. The @code{(guix download)} module provides the most common method, @code{url-fetch}, described below. @deffn {Scheme Procedure} url-fetch @var{url} @var{hash-algo} @var{hash} @ [name] [#:executable? #f] Return a fixed-output derivation that fetches data from @var{url} (a string, or a list of strings denoting alternate URLs), which is expected to have hash @var{hash} of type @var{hash-algo} (a symbol). By default, the file name is the base name of URL; optionally, @var{name} can specify a different file name. When @var{executable?} is true, make the downloaded file executable. When one of the URL starts with @code{mirror://}, then its host part is interpreted as the name of a mirror scheme, taken from @file{%mirror-file}. Alternatively, when URL starts with @code{file://}, return the corresponding file name in the store. @end deffn Likewise, the @code{(guix git-download)} module defines the @code{git-fetch} origin method, which fetches data from a Git version control repository, and the @code{git-reference} data type to describe the repository and revision to fetch. @deffn {Scheme Procedure} git-fetch @var{ref} @var{hash-algo} @var{hash} Return a fixed-output derivation that fetches @var{ref}, a @code{} object. The output is expected to have recursive hash @var{hash} of type @var{hash-algo} (a symbol). Use @var{name} as the file name, or a generic name if @code{#f}. @end deffn @deftp {Data Type} git-reference This data type represents a Git reference for @code{git-fetch} to retrieve. @table @asis @item @code{url} The URL of the Git repository to clone. @item @code{commit} This string denotes either the commit to fetch (a hexadecimal string, either the full SHA1 commit or a ``short'' commit string; the latter is not recommended) or the tag to fetch. @item @code{recursive?} (default: @code{#f}) This Boolean indicates whether to recursively fetch Git sub-modules. @end table The example below denotes the @code{v2.10} tag of the GNU@tie{}Hello repository: @lisp (git-reference (url "https://git.savannah.gnu.org/git/hello.git") (commit "v2.10")) @end lisp This is equivalent to the reference below, which explicitly names the commit: @lisp (git-reference (url "https://git.savannah.gnu.org/git/hello.git") (commit "dc7dc56a00e48fe6f231a58f6537139fe2908fb9")) @end lisp @end deftp For Mercurial repositories, the module @code{(guix hg-download)} defines the @code{hg-fetch} origin method and @code{hg-reference} data type for support of the Mercurial version control system. @deffn {Scheme Procedure} hg-fetch @var{ref} @var{hash-algo} @var{hash} @ [name] Return a fixed-output derivation that fetches @var{ref}, a @code{} object. The output is expected to have recursive hash @var{hash} of type @var{hash-algo} (a symbol). Use @var{name} as the file name, or a generic name if @code{#false}. @end deffn @node Defining Package Variants @section Defining Package Variants @cindex customizing packages @cindex variants, of packages One of the nice things with Guix is that, given a package definition, you can easily @emph{derive} variants of that package---for a different upstream version, with different dependencies, different compilation options, and so on. Some of these custom packages can be defined straight from the command line (@pxref{Package Transformation Options}). This section describes how to define package variants in code. This can be useful in ``manifests'' (@pxref{profile-manifest, @option{--manifest}}) and in your own package collection (@pxref{Creating a Channel}), among others! @cindex inherit, for package definitions As discussed earlier, packages are first-class objects in the Scheme language. The @code{(guix packages)} module provides the @code{package} construct to define new package objects (@pxref{package Reference}). The easiest way to define a package variant is using the @code{inherit} keyword together with @code{package}. This allows you to inherit from a package definition while overriding the fields you want. For example, given the @code{hello} variable, which contains a definition for the current version of GNU@tie{}Hello, here's how you would define a variant for version 2.2 (released in 2006, it's vintage!): @lisp (use-modules (gnu packages base)) ;for 'hello' (define hello-2.2 (package (inherit hello) (version "2.2") (source (origin (method url-fetch) (uri (string-append "mirror://gnu/hello/hello-" version ".tar.gz")) (sha256 (base32 "0lappv4slgb5spyqbh6yl5r013zv72yqg2pcl30mginf3wdqd8k9")))))) @end lisp The example above corresponds to what the @option{--with-source} package transformation option does. Essentially @code{hello-2.2} preserves all the fields of @code{hello}, except @code{version} and @code{source}, which it overrides. Note that the original @code{hello} variable is still there, in the @code{(gnu packages base)} module, unchanged. When you define a custom package like this, you are really @emph{adding} a new package definition; the original one remains available. You can just as well define variants with a different set of dependencies than the original package. For example, the default @code{gdb} package depends on @code{guile}, but since that is an optional dependency, you can define a variant that removes that dependency like so: @lisp (use-modules (gnu packages gdb) ;for 'gdb' (srfi srfi-1)) ;for 'alist-delete' (define gdb-sans-guile (package (inherit gdb) (inputs (alist-delete "guile" (package-inputs gdb))))) @end lisp The @code{alist-delete} call above removes the tuple from the @code{inputs} field that has @code{"guile"} as its first element (@pxref{SRFI-1 Association Lists,,, guile, GNU Guile Reference Manual}). In some cases, you may find it useful to write functions (``procedures'', in Scheme parlance) that return a package based on some parameters. For example, consider the @code{luasocket} library for the Lua programming language. We want to create @code{luasocket} packages for major versions of Lua. One way to do that is to define a procedure that takes a Lua package and returns a @code{luasocket} package that depends on it: @lisp (define (make-lua-socket name lua) ;; Return a luasocket package built with LUA. (package (name name) (version "3.0") ;; several fields omitted (inputs `(("lua" ,lua))) (synopsis "Socket library for Lua"))) (define-public lua5.1-socket (make-lua-socket "lua5.1-socket" lua-5.1)) (define-public lua5.2-socket (make-lua-socket "lua5.2-socket" lua-5.2)) @end lisp Here we have defined packages @code{lua5.1-socket} and @code{lua5.2-socket} by calling @code{make-lua-socket} with different arguments. @xref{Procedures,,, guile, GNU Guile Reference Manual}, for more info on procedures. Having top-level public definitions for these two packages means that they can be referred to from the command line (@pxref{Package Modules}). @cindex package transformations These are pretty simple package variants. As a convenience, the @code{(guix transformations)} module provides a high-level interface that directly maps to the more sophisticated package transformation options (@pxref{Package Transformation Options}): @deffn {Scheme Procedure} options->transformation @var{opts} Return a procedure that, when passed an object to build (package, derivation, etc.), applies the transformations specified by @var{opts} and returns the resulting objects. @var{opts} must be a list of symbol/string pairs such as: @lisp ((with-branch . "guile-gcrypt=master") (without-tests . "libgcrypt")) @end lisp Each symbol names a transformation and the corresponding string is an argument to that transformation. @end deffn For instance, a manifest equivalent to this command: @example guix build guix \ --with-branch=guile-gcrypt=master \ --with-debug-info=zlib @end example @noindent ... would look like this: @lisp (use-modules (guix transformations)) (define transform ;; The package transformation procedure. (options->transformation '((with-branch . "guile-gcrypt=master") (with-debug-info . "zlib")))) (packages->manifest (list (transform (specification->package "guix")))) @end lisp @cindex input rewriting @cindex dependency graph rewriting The @code{options->transformation} procedure is convenient, but it's perhaps also not as flexible as you may like. How is it implemented? The astute reader probably noticed that most package transformation options go beyond the superficial changes shown in the first examples of this section: they involve @dfn{input rewriting}, whereby the dependency graph of a package is rewritten by replacing specific inputs by others. Dependency graph rewriting, for the purposes of swapping packages in the graph, is what the @code{package-input-rewriting} procedure in @code{(guix packages)} implements. @deffn {Scheme Procedure} package-input-rewriting @var{replacements} @ [@var{rewrite-name}] [#:deep? #t] Return a procedure that, when passed a package, replaces its direct and indirect dependencies, including implicit inputs when @var{deep?} is true, according to @var{replacements}. @var{replacements} is a list of package pairs; the first element of each pair is the package to replace, and the second one is the replacement. Optionally, @var{rewrite-name} is a one-argument procedure that takes the name of a package and returns its new name after rewrite. @end deffn @noindent Consider this example: @lisp (define libressl-instead-of-openssl ;; This is a procedure to replace OPENSSL by LIBRESSL, ;; recursively. (package-input-rewriting `((,openssl . ,libressl)))) (define git-with-libressl (libressl-instead-of-openssl git)) @end lisp @noindent Here we first define a rewriting procedure that replaces @var{openssl} with @var{libressl}. Then we use it to define a @dfn{variant} of the @var{git} package that uses @var{libressl} instead of @var{openssl}. This is exactly what the @option{--with-input} command-line option does (@pxref{Package Transformation Options, @option{--with-input}}). The following variant of @code{package-input-rewriting} can match packages to be replaced by name rather than by identity. @deffn {Scheme Procedure} package-input-rewriting/spec @var{replacements} [#:deep? #t] Return a procedure that, given a package, applies the given @var{replacements} to all the package graph, including implicit inputs unless @var{deep?} is false. @var{replacements} is a list of spec/procedures pair; each spec is a package specification such as @code{"gcc"} or @code{"guile@@2"}, and each procedure takes a matching package and returns a replacement for that package. @end deffn The example above could be rewritten this way: @lisp (define libressl-instead-of-openssl ;; Replace all the packages called "openssl" with LibreSSL. (package-input-rewriting/spec `(("openssl" . ,(const libressl))))) @end lisp The key difference here is that, this time, packages are matched by spec and not by identity. In other words, any package in the graph that is called @code{openssl} will be replaced. A more generic procedure to rewrite a package dependency graph is @code{package-mapping}: it supports arbitrary changes to nodes in the graph. @deffn {Scheme Procedure} package-mapping @var{proc} [@var{cut?}] [#:deep? #f] Return a procedure that, given a package, applies @var{proc} to all the packages depended on and returns the resulting package. The procedure stops recursion when @var{cut?} returns true for a given package. When @var{deep?} is true, @var{proc} is applied to implicit inputs as well. @end deffn @node Build Systems @section Build Systems @cindex build system Each package definition specifies a @dfn{build system} and arguments for that build system (@pxref{Defining Packages}). This @code{build-system} field represents the build procedure of the package, as well as implicit dependencies of that build procedure. Build systems are @code{} objects. The interface to create and manipulate them is provided by the @code{(guix build-system)} module, and actual build systems are exported by specific modules. @cindex bag (low-level package representation) Under the hood, build systems first compile package objects to @dfn{bags}. A @dfn{bag} is like a package, but with less ornamentation---in other words, a bag is a lower-level representation of a package, which includes all the inputs of that package, including some that were implicitly added by the build system. This intermediate representation is then compiled to a derivation (@pxref{Derivations}). The @code{package-with-c-toolchain} is an example of a way to change the implicit inputs that a package's build system pulls in (@pxref{package Reference, @code{package-with-c-toolchain}}). Build systems accept an optional list of @dfn{arguments}. In package definitions, these are passed @i{via} the @code{arguments} field (@pxref{Defining Packages}). They are typically keyword arguments (@pxref{Optional Arguments, keyword arguments in Guile,, guile, GNU Guile Reference Manual}). The value of these arguments is usually evaluated in the @dfn{build stratum}---i.e., by a Guile process launched by the daemon (@pxref{Derivations}). The main build system is @code{gnu-build-system}, which implements the standard build procedure for GNU and many other packages. It is provided by the @code{(guix build-system gnu)} module. @defvr {Scheme Variable} gnu-build-system @code{gnu-build-system} represents the GNU Build System, and variants thereof (@pxref{Configuration, configuration and makefile conventions,, standards, GNU Coding Standards}). @cindex build phases In a nutshell, packages using it are configured, built, and installed with the usual @code{./configure && make && make check && make install} command sequence. In practice, a few additional steps are often needed. All these steps are split up in separate @dfn{phases}, notably@footnote{Please see the @code{(guix build gnu-build-system)} modules for more details about the build phases.}: @table @code @item unpack Unpack the source tarball, and change the current directory to the extracted source tree. If the source is actually a directory, copy it to the build tree, and enter that directory. @item patch-source-shebangs Patch shebangs encountered in source files so they refer to the right store file names. For instance, this changes @code{#!/bin/sh} to @code{#!/gnu/store/@dots{}-bash-4.3/bin/sh}. @item configure Run the @file{configure} script with a number of default options, such as @option{--prefix=/gnu/store/@dots{}}, as well as the options specified by the @code{#:configure-flags} argument. @item build Run @code{make} with the list of flags specified with @code{#:make-flags}. If the @code{#:parallel-build?} argument is true (the default), build with @code{make -j}. @item check Run @code{make check}, or some other target specified with @code{#:test-target}, unless @code{#:tests? #f} is passed. If the @code{#:parallel-tests?} argument is true (the default), run @code{make check -j}. @item install Run @code{make install} with the flags listed in @code{#:make-flags}. @item patch-shebangs Patch shebangs on the installed executable files. @item strip Strip debugging symbols from ELF files (unless @code{#:strip-binaries?} is false), copying them to the @code{debug} output when available (@pxref{Installing Debugging Files}). @end table @vindex %standard-phases The build-side module @code{(guix build gnu-build-system)} defines @code{%standard-phases} as the default list of build phases. @code{%standard-phases} is a list of symbol/procedure pairs, where the procedure implements the actual phase. @xref{Build Phases}, for more info on build phases and ways to customize them. In addition, this build system ensures that the ``standard'' environment for GNU packages is available. This includes tools such as GCC, libc, Coreutils, Bash, Make, Diffutils, grep, and sed (see the @code{(guix build-system gnu)} module for a complete list). We call these the @dfn{implicit inputs} of a package, because package definitions do not have to mention them. @end defvr Other @code{} objects are defined to support other conventions and tools used by free software packages. They inherit most of @code{gnu-build-system}, and differ mainly in the set of inputs implicitly added to the build process, and in the list of phases executed. Some of these build systems are listed below. @defvr {Scheme Variable} ant-build-system This variable is exported by @code{(guix build-system ant)}. It implements the build procedure for Java packages that can be built with @url{https://ant.apache.org/, Ant build tool}. It adds both @code{ant} and the @dfn{Java Development Kit} (JDK) as provided by the @code{icedtea} package to the set of inputs. Different packages can be specified with the @code{#:ant} and @code{#:jdk} parameters, respectively. When the original package does not provide a suitable Ant build file, the parameter @code{#:jar-name} can be used to generate a minimal Ant build file @file{build.xml} with tasks to build the specified jar archive. In this case the parameter @code{#:source-dir} can be used to specify the source sub-directory, defaulting to ``src''. The @code{#:main-class} parameter can be used with the minimal ant buildfile to specify the main class of the resulting jar. This makes the jar file executable. The @code{#:test-include} parameter can be used to specify the list of junit tests to run. It defaults to @code{(list "**/*Test.java")}. The @code{#:test-exclude} can be used to disable some tests. It defaults to @code{(list "**/Abstract*.java")}, because abstract classes cannot be run as tests. The parameter @code{#:build-target} can be used to specify the Ant task that should be run during the @code{build} phase. By default the ``jar'' task will be run. @end defvr @defvr {Scheme Variable} android-ndk-build-system @cindex Android distribution @cindex Android NDK build system This variable is exported by @code{(guix build-system android-ndk)}. It implements a build procedure for Android NDK (native development kit) packages using a Guix-specific build process. The build system assumes that packages install their public interface (header) files to the subdirectory @file{include} of the @code{out} output and their libraries to the subdirectory @file{lib} the @code{out} output. It's also assumed that the union of all the dependencies of a package has no conflicting files. For the time being, cross-compilation is not supported - so right now the libraries and header files are assumed to be host tools. @end defvr @defvr {Scheme Variable} asdf-build-system/source @defvrx {Scheme Variable} asdf-build-system/sbcl @defvrx {Scheme Variable} asdf-build-system/ecl These variables, exported by @code{(guix build-system asdf)}, implement build procedures for Common Lisp packages using @url{https://common-lisp.net/project/asdf/, ``ASDF''}. ASDF is a system definition facility for Common Lisp programs and libraries. The @code{asdf-build-system/source} system installs the packages in source form, and can be loaded using any common lisp implementation, via ASDF. The others, such as @code{asdf-build-system/sbcl}, install binary systems in the format which a particular implementation understands. These build systems can also be used to produce executable programs, or lisp images which contain a set of packages pre-loaded. The build system uses naming conventions. For binary packages, the package name should be prefixed with the lisp implementation, such as @code{sbcl-} for @code{asdf-build-system/sbcl}. Additionally, the corresponding source package should be labeled using the same convention as python packages (see @ref{Python Modules}), using the @code{cl-} prefix. In order to create executable programs and images, the build-side procedures @code{build-program} and @code{build-image} can be used. They should be called in a build phase after the @code{create-asdf-configuration} phase, so that the system which was just built can be used within the resulting image. @code{build-program} requires a list of Common Lisp expressions to be passed as the @code{#:entry-program} argument. By default, all the @file{.asd} files present in the sources are read to find system definitions. The @code{#:asd-files} parameter can be used to specify the list of @file{.asd} files to read. Furthermore, if the package defines a system for its tests in a separate file, it will be loaded before the tests are run if it is specified by the @code{#:test-asd-file} parameter. If it is not set, the files @code{-tests.asd}, @code{-test.asd}, @code{tests.asd}, and @code{test.asd} will be tried if they exist. If for some reason the package must be named in a different way than the naming conventions suggest, or if several systems must be compiled, the @code{#:asd-systems} parameter can be used to specify the list of system names. @end defvr @defvr {Scheme Variable} cargo-build-system @cindex Rust programming language @cindex Cargo (Rust build system) This variable is exported by @code{(guix build-system cargo)}. It supports builds of packages using Cargo, the build tool of the @uref{https://www.rust-lang.org, Rust programming language}. It adds @code{rustc} and @code{cargo} to the set of inputs. A different Rust package can be specified with the @code{#:rust} parameter. Regular cargo dependencies should be added to the package definition via the @code{#:cargo-inputs} parameter as a list of name and spec pairs, where the spec can be a package or a source definition. Note that the spec must evaluate to a path to a gzipped tarball which includes a @code{Cargo.toml} file at its root, or it will be ignored. Similarly, cargo dev-dependencies should be added to the package definition via the @code{#:cargo-development-inputs} parameter. In its @code{configure} phase, this build system will make any source inputs specified in the @code{#:cargo-inputs} and @code{#:cargo-development-inputs} parameters available to cargo. It will also remove an included @code{Cargo.lock} file to be recreated by @code{cargo} during the @code{build} phase. The @code{install} phase installs the binaries defined by the crate. @end defvr @defvr {Scheme Variable} chicken-build-system This variable is exported by @code{(guix build-system chicken)}. It builds @uref{https://call-cc.org/, CHICKEN Scheme} modules, also called ``eggs'' or ``extensions''. CHICKEN generates C source code, which then gets compiled by a C compiler, in this case GCC. This build system adds @code{chicken} to the package inputs, as well as the packages of @code{gnu-build-system}. The build system can't (yet) deduce the egg's name automatically, so just like with @code{go-build-system} and its @code{#:import-path}, you should define @code{#:egg-name} in the package's @code{arguments} field. For example, if you are packaging the @code{srfi-1} egg: @lisp (arguments '(#:egg-name "srfi-1")) @end lisp Egg dependencies must be defined in @code{propagated-inputs}, not @code{inputs} because CHICKEN doesn't embed absolute references in compiled eggs. Test dependencies should go to @code{native-inputs}, as usual. @end defvr @defvr {Scheme Variable} copy-build-system This variable is exported by @code{(guix build-system copy)}. It supports builds of simple packages that don't require much compiling, mostly just moving files around. It adds much of the @code{gnu-build-system} packages to the set of inputs. Because of this, the @code{copy-build-system} does not require all the boilerplate code often needed for the @code{trivial-build-system}. To further simplify the file installation process, an @code{#:install-plan} argument is exposed to let the packager specify which files go where. The install plan is a list of @code{(@var{source} @var{target} [@var{filters}])}. @var{filters} are optional. @itemize @item When @var{source} matches a file or directory without trailing slash, install it to @var{target}. @itemize @item If @var{target} has a trailing slash, install @var{source} basename beneath @var{target}. @item Otherwise install @var{source} as @var{target}. @end itemize @item When @var{source} is a directory with a trailing slash, or when @var{filters} are used, the trailing slash of @var{target} is implied with the same meaning as above. @itemize @item Without @var{filters}, install the full @var{source} @emph{content} to @var{target}. @item With @var{filters} among @code{#:include}, @code{#:include-regexp}, @code{#:exclude}, @code{#:exclude-regexp}, only select files are installed depending on the filters. Each filters is specified by a list of strings. @itemize @item With @code{#:include}, install all the files which the path suffix matches at least one of the elements in the given list. @item With @code{#:include-regexp}, install all the files which the subpaths match at least one of the regular expressions in the given list. @item The @code{#:exclude} and @code{#:exclude-regexp} filters are the complement of their inclusion counterpart. Without @code{#:include} flags, install all files but those matching the exclusion filters. If both inclusions and exclusions are specified, the exclusions are done on top of the inclusions. @end itemize @end itemize In all cases, the paths relative to @var{source} are preserved within @var{target}. @end itemize Examples: @itemize @item @code{("foo/bar" "share/my-app/")}: Install @file{bar} to @file{share/my-app/bar}. @item @code{("foo/bar" "share/my-app/baz")}: Install @file{bar} to @file{share/my-app/baz}. @item @code{("foo/" "share/my-app")}: Install the content of @file{foo} inside @file{share/my-app}, e.g., install @file{foo/sub/file} to @file{share/my-app/sub/file}. @item @code{("foo/" "share/my-app" #:include ("sub/file"))}: Install only @file{foo/sub/file} to @file{share/my-app/sub/file}. @item @code{("foo/sub" "share/my-app" #:include ("file"))}: Install @file{foo/sub/file} to @file{share/my-app/file}. @end itemize @end defvr @cindex Clojure (programming language) @cindex simple Clojure build system @defvr {Scheme Variable} clojure-build-system This variable is exported by @code{(guix build-system clojure)}. It implements a simple build procedure for @uref{https://clojure.org/, Clojure} packages using plain old @code{compile} in Clojure. Cross-compilation is not supported yet. It adds @code{clojure}, @code{icedtea} and @code{zip} to the set of inputs. Different packages can be specified with the @code{#:clojure}, @code{#:jdk} and @code{#:zip} parameters, respectively. A list of source directories, test directories and jar names can be specified with the @code{#:source-dirs}, @code{#:test-dirs} and @code{#:jar-names} parameters, respectively. Compile directory and main class can be specified with the @code{#:compile-dir} and @code{#:main-class} parameters, respectively. Other parameters are documented below. This build system is an extension of @code{ant-build-system}, but with the following phases changed: @table @code @item build This phase calls @code{compile} in Clojure to compile source files and runs @command{jar} to create jars from both source files and compiled files according to the include list and exclude list specified in @code{#:aot-include} and @code{#:aot-exclude}, respectively. The exclude list has priority over the include list. These lists consist of symbols representing Clojure libraries or the special keyword @code{#:all} representing all Clojure libraries found under the source directories. The parameter @code{#:omit-source?} decides if source should be included into the jars. @item check This phase runs tests according to the include list and exclude list specified in @code{#:test-include} and @code{#:test-exclude}, respectively. Their meanings are analogous to that of @code{#:aot-include} and @code{#:aot-exclude}, except that the special keyword @code{#:all} now stands for all Clojure libraries found under the test directories. The parameter @code{#:tests?} decides if tests should be run. @item install This phase installs all jars built previously. @end table Apart from the above, this build system also contains an additional phase: @table @code @item install-doc This phase installs all top-level files with base name matching @code{%doc-regex}. A different regex can be specified with the @code{#:doc-regex} parameter. All files (recursively) inside the documentation directories specified in @code{#:doc-dirs} are installed as well. @end table @end defvr @defvr {Scheme Variable} cmake-build-system This variable is exported by @code{(guix build-system cmake)}. It implements the build procedure for packages using the @url{https://www.cmake.org, CMake build tool}. It automatically adds the @code{cmake} package to the set of inputs. Which package is used can be specified with the @code{#:cmake} parameter. The @code{#:configure-flags} parameter is taken as a list of flags passed to the @command{cmake} command. The @code{#:build-type} parameter specifies in abstract terms the flags passed to the compiler; it defaults to @code{"RelWithDebInfo"} (short for ``release mode with debugging information''), which roughly means that code is compiled with @code{-O2 -g}, as is the case for Autoconf-based packages by default. @end defvr @defvr {Scheme Variable} dune-build-system This variable is exported by @code{(guix build-system dune)}. It supports builds of packages using @uref{https://dune.build/, Dune}, a build tool for the OCaml programming language. It is implemented as an extension of the @code{ocaml-build-system} which is described below. As such, the @code{#:ocaml} and @code{#:findlib} parameters can be passed to this build system. It automatically adds the @code{dune} package to the set of inputs. Which package is used can be specified with the @code{#:dune} parameter. There is no @code{configure} phase because dune packages typically don't need to be configured. The @code{#:build-flags} parameter is taken as a list of flags passed to the @code{dune} command during the build. The @code{#:jbuild?} parameter can be passed to use the @code{jbuild} command instead of the more recent @code{dune} command while building a package. Its default value is @code{#f}. The @code{#:package} parameter can be passed to specify a package name, which is useful when a package contains multiple packages and you want to build only one of them. This is equivalent to passing the @code{-p} argument to @code{dune}. @end defvr @defvr {Scheme Variable} go-build-system This variable is exported by @code{(guix build-system go)}. It implements a build procedure for Go packages using the standard @url{https://golang.org/cmd/go/#hdr-Compile_packages_and_dependencies, Go build mechanisms}. The user is expected to provide a value for the key @code{#:import-path} and, in some cases, @code{#:unpack-path}. The @url{https://golang.org/doc/code.html#ImportPaths, import path} corresponds to the file system path expected by the package's build scripts and any referring packages, and provides a unique way to refer to a Go package. It is typically based on a combination of the package source code's remote URI and file system hierarchy structure. In some cases, you will need to unpack the package's source code to a different directory structure than the one indicated by the import path, and @code{#:unpack-path} should be used in such cases. Packages that provide Go libraries should install their source code into the built output. The key @code{#:install-source?}, which defaults to @code{#t}, controls whether or not the source code is installed. It can be set to @code{#f} for packages that only provide executable files. @end defvr @defvr {Scheme Variable} glib-or-gtk-build-system This variable is exported by @code{(guix build-system glib-or-gtk)}. It is intended for use with packages making use of GLib or GTK+. This build system adds the following two phases to the ones defined by @code{gnu-build-system}: @table @code @item glib-or-gtk-wrap The phase @code{glib-or-gtk-wrap} ensures that programs in @file{bin/} are able to find GLib ``schemas'' and @uref{https://developer.gnome.org/gtk3/stable/gtk-running.html, GTK+ modules}. This is achieved by wrapping the programs in launch scripts that appropriately set the @env{XDG_DATA_DIRS} and @env{GTK_PATH} environment variables. It is possible to exclude specific package outputs from that wrapping process by listing their names in the @code{#:glib-or-gtk-wrap-excluded-outputs} parameter. This is useful when an output is known not to contain any GLib or GTK+ binaries, and where wrapping would gratuitously add a dependency of that output on GLib and GTK+. @item glib-or-gtk-compile-schemas The phase @code{glib-or-gtk-compile-schemas} makes sure that all @uref{https://developer.gnome.org/gio/stable/glib-compile-schemas.html, GSettings schemas} of GLib are compiled. Compilation is performed by the @command{glib-compile-schemas} program. It is provided by the package @code{glib:bin} which is automatically imported by the build system. The @code{glib} package providing @command{glib-compile-schemas} can be specified with the @code{#:glib} parameter. @end table Both phases are executed after the @code{install} phase. @end defvr @defvr {Scheme Variable} guile-build-system This build system is for Guile packages that consist exclusively of Scheme code and that are so lean that they don't even have a makefile, let alone a @file{configure} script. It compiles Scheme code using @command{guild compile} (@pxref{Compilation,,, guile, GNU Guile Reference Manual}) and installs the @file{.scm} and @file{.go} files in the right place. It also installs documentation. This build system supports cross-compilation by using the @option{--target} option of @samp{guild compile}. Packages built with @code{guile-build-system} must provide a Guile package in their @code{native-inputs} field. @end defvr @defvr {Scheme Variable} julia-build-system This variable is exported by @code{(guix build-system julia)}. It implements the build procedure used by @uref{https://julialang.org/, julia} packages, which essentially is similar to running @samp{julia -e 'using Pkg; Pkg.add(package)'} in an environment where @env{JULIA_LOAD_PATH} contains the paths to all Julia package inputs. Tests are run with @code{Pkg.test}. Julia packages require the source @code{file-name} to be the real name of the package, correctly capitalized. For packages requiring shared library dependencies, you may need to write the @file{/deps/deps.jl} file manually. It's usually a line of @code{const variable = /gnu/store/library.so} for each dependency, plus a void function @code{check_deps() = nothing}. Some older packages that aren't using @file{Package.toml} yet, will require this file to be created, too. The function @code{julia-create-package-toml} helps creating the file. You need to pass the outputs and the source of the package, it's name (the same as the @code{file-name} parameter), the package uuid, the package version, and a list of dependencies specified by their name and their uuid. @end defvr @defvr {Scheme Variable} maven-build-system This variable is exported by @code{(guix build-system maven)}. It implements a build procedure for @uref{https://maven.apache.org, Maven} packages. Maven is a dependency and lifecycle management tool for Java. A user of Maven specifies dependencies and plugins in a @file{pom.xml} file that Maven reads. When Maven does not have one of the dependencies or plugins in its repository, it will download them and use them to build the package. The maven build system ensures that maven will not try to download any dependency by running in offline mode. Maven will fail if a dependency is missing. Before running Maven, the @file{pom.xml} (and subprojects) are modified to specify the version of dependencies and plugins that match the versions available in the guix build environment. Dependencies and plugins must be installed in the fake maven repository at @file{lib/m2}, and are symlinked into a proper repository before maven is run. Maven is instructed to use that repository for the build and installs built artifacts there. Changed files are copied to the @file{lib/m2} directory of the package output. You can specify a @file{pom.xml} file with the @code{#:pom-file} argument, or let the build system use the default @file{pom.xml} file in the sources. In case you need to specify a dependency's version manually, you can use the @code{#:local-packages} argument. It takes an association list where the key is the groupId of the package and its value is an association list where the key is the artifactId of the package and its value is the version you want to override in the @file{pom.xml}. Some packages use dependencies or plugins that are not useful at runtime nor at build time in Guix. You can alter the @file{pom.xml} file to remove them using the @code{#:exclude} argument. Its value is an association list where the key is the groupId of the plugin or dependency you want to remove, and the value is a list of artifactId you want to remove. You can override the default @code{jdk} and @code{maven} packages with the corresponding argument, @code{#:jdk} and @code{#:maven}. The @code{#:maven-plugins} argument is a list of maven plugins used during the build, with the same format as the @code{inputs} fields of the package declaration. Its default value is @code{(default-maven-plugins)} which is also exported. @end defvr @defvr {Scheme Variable} minify-build-system This variable is exported by @code{(guix build-system minify)}. It implements a minification procedure for simple JavaScript packages. It adds @code{uglify-js} to the set of inputs and uses it to compress all JavaScript files in the @file{src} directory. A different minifier package can be specified with the @code{#:uglify-js} parameter, but it is expected that the package writes the minified code to the standard output. When the input JavaScript files are not all located in the @file{src} directory, the parameter @code{#:javascript-files} can be used to specify a list of file names to feed to the minifier. @end defvr @defvr {Scheme Variable} ocaml-build-system This variable is exported by @code{(guix build-system ocaml)}. It implements a build procedure for @uref{https://ocaml.org, OCaml} packages, which consists of choosing the correct set of commands to run for each package. OCaml packages can expect many different commands to be run. This build system will try some of them. When the package has a @file{setup.ml} file present at the top-level, it will run @code{ocaml setup.ml -configure}, @code{ocaml setup.ml -build} and @code{ocaml setup.ml -install}. The build system will assume that this file was generated by @uref{http://oasis.forge.ocamlcore.org/, OASIS} and will take care of setting the prefix and enabling tests if they are not disabled. You can pass configure and build flags with the @code{#:configure-flags} and @code{#:build-flags}. The @code{#:test-flags} key can be passed to change the set of flags used to enable tests. The @code{#:use-make?} key can be used to bypass this system in the build and install phases. When the package has a @file{configure} file, it is assumed that it is a hand-made configure script that requires a different argument format than in the @code{gnu-build-system}. You can add more flags with the @code{#:configure-flags} key. When the package has a @file{Makefile} file (or @code{#:use-make?} is @code{#t}), it will be used and more flags can be passed to the build and install phases with the @code{#:make-flags} key. Finally, some packages do not have these files and use a somewhat standard location for its build system. In that case, the build system will run @code{ocaml pkg/pkg.ml} or @code{ocaml pkg/build.ml} and take care of providing the path to the required findlib module. Additional flags can be passed via the @code{#:build-flags} key. Install is taken care of by @command{opam-installer}. In this case, the @code{opam} package must be added to the @code{native-inputs} field of the package definition. Note that most OCaml packages assume they will be installed in the same directory as OCaml, which is not what we want in guix. In particular, they will install @file{.so} files in their module's directory, which is usually fine because it is in the OCaml compiler directory. In guix though, these libraries cannot be found and we use @env{CAML_LD_LIBRARY_PATH}. This variable points to @file{lib/ocaml/site-lib/stubslibs} and this is where @file{.so} libraries should be installed. @end defvr @defvr {Scheme Variable} python-build-system This variable is exported by @code{(guix build-system python)}. It implements the more or less standard build procedure used by Python packages, which consists in running @code{python setup.py build} and then @code{python setup.py install --prefix=/gnu/store/@dots{}}. For packages that install stand-alone Python programs under @code{bin/}, it takes care of wrapping these programs so that their @env{PYTHONPATH} environment variable points to all the Python libraries they depend on. Which Python package is used to perform the build can be specified with the @code{#:python} parameter. This is a useful way to force a package to be built for a specific version of the Python interpreter, which might be necessary if the package is only compatible with a single interpreter version. By default guix calls @code{setup.py} under control of @code{setuptools}, much like @command{pip} does. Some packages are not compatible with setuptools (and pip), thus you can disable this by setting the @code{#:use-setuptools?} parameter to @code{#f}. @end defvr @defvr {Scheme Variable} perl-build-system This variable is exported by @code{(guix build-system perl)}. It implements the standard build procedure for Perl packages, which either consists in running @code{perl Build.PL --prefix=/gnu/store/@dots{}}, followed by @code{Build} and @code{Build install}; or in running @code{perl Makefile.PL PREFIX=/gnu/store/@dots{}}, followed by @code{make} and @code{make install}, depending on which of @code{Build.PL} or @code{Makefile.PL} is present in the package distribution. Preference is given to the former if both @code{Build.PL} and @code{Makefile.PL} exist in the package distribution. This preference can be reversed by specifying @code{#t} for the @code{#:make-maker?} parameter. The initial @code{perl Makefile.PL} or @code{perl Build.PL} invocation passes flags specified by the @code{#:make-maker-flags} or @code{#:module-build-flags} parameter, respectively. Which Perl package is used can be specified with @code{#:perl}. @end defvr @defvr {Scheme Variable} qt-build-system This variable is exported by @code{(guix build-system qt)}. It is intended for use with applications using Qt or KDE. This build system adds the following two phases to the ones defined by @code{cmake-build-system}: @table @code @item check-setup The phase @code{check-setup} prepares the environment for running the checks as commonly used by Qt test programs. For now this only sets some environment variables: @code{QT_QPA_PLATFORM=offscreen}, @code{DBUS_FATAL_WARNINGS=0} and @code{CTEST_OUTPUT_ON_FAILURE=1}. This phase is added before the @code{check} phase. It's a separate phase to ease adjusting if necessary. @item qt-wrap The phase @code{qt-wrap} searches for Qt5 plugin paths, QML paths and some XDG in the inputs and output. In case some path is found, all programs in the output's @file{bin/}, @file{sbin/}, @file{libexec/} and @file{lib/libexec/} directories are wrapped in scripts defining the necessary environment variables. It is possible to exclude specific package outputs from that wrapping process by listing their names in the @code{#:qt-wrap-excluded-outputs} parameter. This is useful when an output is known not to contain any Qt binaries, and where wrapping would gratuitously add a dependency of that output on Qt, KDE, or such. This phase is added after the @code{install} phase. @end table @end defvr @defvr {Scheme Variable} r-build-system This variable is exported by @code{(guix build-system r)}. It implements the build procedure used by @uref{https://r-project.org, R} packages, which essentially is little more than running @samp{R CMD INSTALL --library=/gnu/store/@dots{}} in an environment where @env{R_LIBS_SITE} contains the paths to all R package inputs. Tests are run after installation using the R function @code{tools::testInstalledPackage}. @end defvr @defvr {Scheme Variable} rakudo-build-system This variable is exported by @code{(guix build-system rakudo)}. It implements the build procedure used by @uref{https://rakudo.org/, Rakudo} for @uref{https://perl6.org/, Perl6} packages. It installs the package to @code{/gnu/store/@dots{}/NAME-VERSION/share/perl6} and installs the binaries, library files and the resources, as well as wrap the files under the @code{bin/} directory. Tests can be skipped by passing @code{#f} to the @code{tests?} parameter. Which rakudo package is used can be specified with @code{rakudo}. Which perl6-tap-harness package used for the tests can be specified with @code{#:prove6} or removed by passing @code{#f} to the @code{with-prove6?} parameter. Which perl6-zef package used for tests and installing can be specified with @code{#:zef} or removed by passing @code{#f} to the @code{with-zef?} parameter. @end defvr @defvr {Scheme Variable} texlive-build-system This variable is exported by @code{(guix build-system texlive)}. It is used to build TeX packages in batch mode with a specified engine. The build system sets the @env{TEXINPUTS} variable to find all TeX source files in the inputs. By default it runs @code{luatex} on all files ending on @code{ins}. A different engine and format can be specified with the @code{#:tex-format} argument. Different build targets can be specified with the @code{#:build-targets} argument, which expects a list of file names. The build system adds only @code{texlive-bin} and @code{texlive-latex-base} (both from @code{(gnu packages tex}) to the inputs. Both can be overridden with the arguments @code{#:texlive-bin} and @code{#:texlive-latex-base}, respectively. The @code{#:tex-directory} parameter tells the build system where to install the built files under the texmf tree. @end defvr @defvr {Scheme Variable} ruby-build-system This variable is exported by @code{(guix build-system ruby)}. It implements the RubyGems build procedure used by Ruby packages, which involves running @code{gem build} followed by @code{gem install}. The @code{source} field of a package that uses this build system typically references a gem archive, since this is the format that Ruby developers use when releasing their software. The build system unpacks the gem archive, potentially patches the source, runs the test suite, repackages the gem, and installs it. Additionally, directories and tarballs may be referenced to allow building unreleased gems from Git or a traditional source release tarball. Which Ruby package is used can be specified with the @code{#:ruby} parameter. A list of additional flags to be passed to the @command{gem} command can be specified with the @code{#:gem-flags} parameter. @end defvr @defvr {Scheme Variable} waf-build-system This variable is exported by @code{(guix build-system waf)}. It implements a build procedure around the @code{waf} script. The common phases---@code{configure}, @code{build}, and @code{install}---are implemented by passing their names as arguments to the @code{waf} script. The @code{waf} script is executed by the Python interpreter. Which Python package is used to run the script can be specified with the @code{#:python} parameter. @end defvr @defvr {Scheme Variable} scons-build-system This variable is exported by @code{(guix build-system scons)}. It implements the build procedure used by the SCons software construction tool. This build system runs @code{scons} to build the package, @code{scons test} to run tests, and then @code{scons install} to install the package. Additional flags to be passed to @code{scons} can be specified with the @code{#:scons-flags} parameter. The default build and install targets can be overridden with @code{#:build-targets} and @code{#:install-targets} respectively. The version of Python used to run SCons can be specified by selecting the appropriate SCons package with the @code{#:scons} parameter. @end defvr @defvr {Scheme Variable} haskell-build-system This variable is exported by @code{(guix build-system haskell)}. It implements the Cabal build procedure used by Haskell packages, which involves running @code{runhaskell Setup.hs configure --prefix=/gnu/store/@dots{}} and @code{runhaskell Setup.hs build}. Instead of installing the package by running @code{runhaskell Setup.hs install}, to avoid trying to register libraries in the read-only compiler store directory, the build system uses @code{runhaskell Setup.hs copy}, followed by @code{runhaskell Setup.hs register}. In addition, the build system generates the package documentation by running @code{runhaskell Setup.hs haddock}, unless @code{#:haddock? #f} is passed. Optional Haddock parameters can be passed with the help of the @code{#:haddock-flags} parameter. If the file @code{Setup.hs} is not found, the build system looks for @code{Setup.lhs} instead. Which Haskell compiler is used can be specified with the @code{#:haskell} parameter which defaults to @code{ghc}. @end defvr @defvr {Scheme Variable} dub-build-system This variable is exported by @code{(guix build-system dub)}. It implements the Dub build procedure used by D packages, which involves running @code{dub build} and @code{dub run}. Installation is done by copying the files manually. Which D compiler is used can be specified with the @code{#:ldc} parameter which defaults to @code{ldc}. @end defvr @anchor{emacs-build-system} @defvr {Scheme Variable} emacs-build-system This variable is exported by @code{(guix build-system emacs)}. It implements an installation procedure similar to the packaging system of Emacs itself (@pxref{Packages,,, emacs, The GNU Emacs Manual}). It first creates the @code{@code{package}-autoloads.el} file, then it byte compiles all Emacs Lisp files. Differently from the Emacs packaging system, the Info documentation files are moved to the standard documentation directory and the @file{dir} file is deleted. The Elisp package files are installed directly under @file{share/emacs/site-lisp}. @end defvr @defvr {Scheme Variable} font-build-system This variable is exported by @code{(guix build-system font)}. It implements an installation procedure for font packages where upstream provides pre-compiled TrueType, OpenType, etc.@: font files that merely need to be copied into place. It copies font files to standard locations in the output directory. @end defvr @defvr {Scheme Variable} meson-build-system This variable is exported by @code{(guix build-system meson)}. It implements the build procedure for packages that use @url{https://mesonbuild.com, Meson} as their build system. It adds both Meson and @uref{https://ninja-build.org/, Ninja} to the set of inputs, and they can be changed with the parameters @code{#:meson} and @code{#:ninja} if needed. The default Meson is @code{meson-for-build}, which is special because it doesn't clear the @code{RUNPATH} of binaries and libraries when they are installed. This build system is an extension of @code{gnu-build-system}, but with the following phases changed to some specific for Meson: @table @code @item configure The phase runs @code{meson} with the flags specified in @code{#:configure-flags}. The flag @option{--buildtype} is always set to @code{debugoptimized} unless something else is specified in @code{#:build-type}. @item build The phase runs @code{ninja} to build the package in parallel by default, but this can be changed with @code{#:parallel-build?}. @item check The phase runs @code{ninja} with the target specified in @code{#:test-target}, which is @code{"test"} by default. @item install The phase runs @code{ninja install} and can not be changed. @end table Apart from that, the build system also adds the following phases: @table @code @item fix-runpath This phase ensures that all binaries can find the libraries they need. It searches for required libraries in subdirectories of the package being built, and adds those to @code{RUNPATH} where needed. It also removes references to libraries left over from the build phase by @code{meson-for-build}, such as test dependencies, that aren't actually required for the program to run. @item glib-or-gtk-wrap This phase is the phase provided by @code{glib-or-gtk-build-system}, and it is not enabled by default. It can be enabled with @code{#:glib-or-gtk?}. @item glib-or-gtk-compile-schemas This phase is the phase provided by @code{glib-or-gtk-build-system}, and it is not enabled by default. It can be enabled with @code{#:glib-or-gtk?}. @end table @end defvr @defvr {Scheme Variable} linux-module-build-system @code{linux-module-build-system} allows building Linux kernel modules. @cindex build phases This build system is an extension of @code{gnu-build-system}, but with the following phases changed: @table @code @item configure This phase configures the environment so that the Linux kernel's Makefile can be used to build the external kernel module. @item build This phase uses the Linux kernel's Makefile in order to build the external kernel module. @item install This phase uses the Linux kernel's Makefile in order to install the external kernel module. @end table It is possible and useful to specify the Linux kernel to use for building the module (in the @code{arguments} form of a package using the @code{linux-module-build-system}, use the key @code{#:linux} to specify it). @end defvr @defvr {Scheme Variable} node-build-system This variable is exported by @code{(guix build-system node)}. It implements the build procedure used by @uref{https://nodejs.org, Node.js}, which implements an approximation of the @code{npm install} command, followed by an @code{npm test} command. Which Node.js package is used to interpret the @code{npm} commands can be specified with the @code{#:node} parameter which defaults to @code{node}. @end defvr Lastly, for packages that do not need anything as sophisticated, a ``trivial'' build system is provided. It is trivial in the sense that it provides basically no support: it does not pull any implicit inputs, and does not have a notion of build phases. @defvr {Scheme Variable} trivial-build-system This variable is exported by @code{(guix build-system trivial)}. This build system requires a @code{#:builder} argument. This argument must be a Scheme expression that builds the package output(s)---as with @code{build-expression->derivation} (@pxref{Derivations, @code{build-expression->derivation}}). @end defvr @node Build Phases @section Build Phases @cindex build phases, for packages Almost all package build systems implement a notion @dfn{build phases}: a sequence of actions that the build system executes, when you build the package, leading to the installed byproducts in the store. A notable exception is the ``bare-bones'' @code{trivial-build-system} (@pxref{Build Systems}). As discussed in the previous section, those build systems provide a standard list of phases. For @code{gnu-build-system}, the standard phases include an @code{unpack} phase to unpack the source code tarball, a @command{configure} phase to run @code{./configure}, a @code{build} phase to run @command{make}, and (among others) an @code{install} phase to run @command{make install}; @pxref{Build Systems}, for a more detailed view of these phases. Likewise, @code{cmake-build-system} inherits these phases, but its @code{configure} phase runs @command{cmake} instead of @command{./configure}. Other build systems, such as @code{python-build-system}, have a wholly different list of standard phases. All this code runs on the @dfn{build side}: it is evaluated when you actually build the package, in a dedicated build process spawned by the build daemon (@pxref{Invoking guix-daemon}). Build phases are represented as association lists or ``alists'' (@pxref{Association Lists,,, guile, GNU Guile Reference Manual}) where each key is a symbol for the name of the phase and the associated value is a procedure that accepts an arbitrary number of arguments. By convention, those procedures receive information about the build in the form of @dfn{keyword parameters}, which they can use or ignore. For example, here is how @code{(guix build gnu-build-system)} defines @code{%standard-phases}, the variable holding its alist of build phases@footnote{We present a simplified view of those build phases, but do take a look at @code{(guix build gnu-build-system)} to see all the details!}: @lisp ;; The build phases of 'gnu-build-system'. (define* (unpack #:key source #:allow-other-keys) ;; Extract the source tarball. (invoke "tar" "xvf" source)) (define* (configure #:key outputs #:allow-other-keys) ;; Run the 'configure' script. Install to output "out". (let ((out (assoc-ref outputs "out"))) (invoke "./configure" (string-append "--prefix=" out)))) (define* (build #:allow-other-keys) ;; Compile. (invoke "make")) (define* (check #:key (test-target "check") (tests? #true) #:allow-other-keys) ;; Run the test suite. (if tests? (invoke "make" test-target) (display "test suite not run\n"))) (define* (install #:allow-other-keys) ;; Install files to the prefix 'configure' specified. (invoke "make" "install")) (define %standard-phases ;; The list of standard phases (quite a few are omitted ;; for brevity). Each element is a symbol/procedure pair. (list (cons 'unpack unpack) (cons 'configure configure) (cons 'build build) (cons 'check check) (cons 'install install))) @end lisp This shows how @code{%standard-phases} is defined as a list of symbol/procedure pairs (@pxref{Pairs,,, guile, GNU Guile Reference Manual}). The first pair associates the @code{unpack} procedure with the @code{unpack} symbol---a name; the second pair defines the @code{configure} phase similarly, and so on. When building a package that uses @code{gnu-build-system} with its default list of phases, those phases are executed sequentially. You can see the name of each phase started and completed in the build log of packages that you build. Let's now look at the procedures themselves. Each one is defined with @code{define*}: @code{#:key} lists keyword parameters the procedure accepts, possibly with a default value, and @code{#:allow-other-keys} specifies that other keyword parameters are ignored (@pxref{Optional Arguments,,, guile, GNU Guile Reference Manual}). The @code{unpack} procedure honors the @code{source} parameter, which the build system uses to pass the file name of the source tarball (or version control checkout), and it ignores other parameters. The @code{configure} phase only cares about the @code{outputs} parameter, an alist mapping package output names to their store file name (@pxref{Packages with Multiple Outputs}). It extracts the file name of for @code{out}, the default output, and passes it to @command{./configure} as the installation prefix, meaning that @command{make install} will eventually copy all the files in that directory (@pxref{Configuration, configuration and makefile conventions,, standards, GNU Coding Standards}). @code{build} and @code{install} ignore all their arguments. @code{check} honors the @code{test-target} argument, which specifies the name of the Makefile target to run tests; it prints a message and skips tests when @code{tests?} is false. @cindex build phases, customizing The list of phases used for a particular package can be changed with the @code{#:phases} parameter of the build system. Changing the set of build phases boils down to building a new alist of phases based on the @code{%standard-phases} alist described above. This can be done with standard alist procedures such as @code{alist-delete} (@pxref{SRFI-1 Association Lists,,, guile, GNU Guile Reference Manual}); however, it is more convenient to do so with @code{modify-phases} (@pxref{Build Utilities, @code{modify-phases}}). Here is an example of a package definition that removes the @code{configure} phase of @code{%standard-phases} and inserts a new phase before the @code{build} phase, called @code{set-prefix-in-makefile}: @lisp (define-public example (package (name "example") ;; other fields omitted (build-system gnu-build-system) (arguments '(#:phases (modify-phases %standard-phases (delete 'configure) (add-before 'build 'set-prefix-in-makefile (lambda* (#:key outputs #:allow-other-keys) ;; Modify the makefile so that its ;; 'PREFIX' variable points to "out". (let ((out (assoc-ref outputs "out"))) (substitute* "Makefile" (("PREFIX =.*") (string-append "PREFIX = " out "\n"))) #true)))))))) @end lisp The new phase that is inserted is written as an anonymous procedure, introduced with @code{lambda*}; it honors the @code{outputs} parameter we have seen before. @xref{Build Utilities}, for more about the helpers used by this phase, and for more examples of @code{modify-phases}. @cindex code staging @cindex staging, of code Keep in mind that build phases are code evaluated at the time the package is actually built. This explains why the whole @code{modify-phases} expression above is quoted (it comes after the @code{'} or apostrophe): it is @dfn{staged} for later execution. @xref{G-Expressions}, for an explanation of code staging and the @dfn{code strata} involved. @node Build Utilities @section Build Utilities As soon as you start writing non-trivial package definitions (@pxref{Defining Packages}) or other build actions (@pxref{G-Expressions}), you will likely start looking for helpers for ``shell-like'' actions---creating directories, copying and deleting files recursively, manipulating build phases, and so on. The @code{(guix build utils)} module provides such utility procedures. Most build systems load @code{(guix build utils)} (@pxref{Build Systems}). Thus, when writing custom build phases for your package definitions, you can usually assume those procedures are in scope. When writing G-expressions, you can import @code{(guix build utils)} on the ``build side'' using @code{with-imported-modules} and then put it in scope with the @code{use-modules} form (@pxref{Using Guile Modules,,, guile, GNU Guile Reference Manual}): @lisp (with-imported-modules '((guix build utils)) ;import it (computed-file "empty-tree" #~(begin ;; Put it in scope. (use-modules (guix build utils)) ;; Happily use its 'mkdir-p' procedure. (mkdir-p (string-append #$output "/a/b/c"))))) @end lisp The remainder of this section is the reference for most of the utility procedures provided by @code{(guix build utils)}. @c TODO Document what's missing. @subsection Dealing with Store File Names This section documents procedures that deal with store file names. @deffn {Scheme Procedure} %store-directory Return the directory name of the store. @end deffn @deffn {Scheme Procedure} store-file-name? @var{file} Return true if @var{file} is in the store. @end deffn @deffn {Scheme Procedure} strip-store-file-name @var{file} Strip the @file{/gnu/store} and hash from @var{file}, a store file name. The result is typically a @code{"@var{package}-@var{version}"} string. @end deffn @deffn {Scheme Procedure} package-name->name+version @var{name} Given @var{name}, a package name like @code{"foo-0.9.1b"}, return two values: @code{"foo"} and @code{"0.9.1b"}. When the version part is unavailable, @var{name} and @code{#f} are returned. The first hyphen followed by a digit is considered to introduce the version part. @end deffn @subsection File Types The procedures below deal with files and file types. @deffn {Scheme Procedure} directory-exists? @var{dir} Return @code{#t} if @var{dir} exists and is a directory. @end deffn @deffn {Scheme Procedure} executable-file? @var{file} Return @code{#t} if @var{file} exists and is executable. @end deffn @deffn {Scheme Procedure} symbolic-link? @var{file} Return @code{#t} if @var{file} is a symbolic link (aka. a ``symlink''). @end deffn @deffn {Scheme Procedure} elf-file? @var{file} @deffnx {Scheme Procedure} ar-file? @var{file} @deffnx {Scheme Procedure} gzip-file? @var{file} Return @code{#t} if @var{file} is, respectively, an ELF file, an @code{ar} archive (such as a @file{.a} static library), or a gzip file. @end deffn @deffn {Scheme Procedure} reset-gzip-timestamp @var{file} [#:keep-mtime? #t] If @var{file} is a gzip file, reset its embedded timestamp (as with @command{gzip --no-name}) and return true. Otherwise return @code{#f}. When @var{keep-mtime?} is true, preserve @var{file}'s modification time. @end deffn @subsection File Manipulation The following procedures and macros help create, modify, and delete files. They provide functionality comparable to common shell utilities such as @command{mkdir -p}, @command{cp -r}, @command{rm -r}, and @command{sed}. They complement Guile's extensive, but low-level, file system interface (@pxref{POSIX,,, guile, GNU Guile Reference Manual}). @deffn {Scheme Syntax} with-directory-excursion @var{directory} @var{body}@dots{} Run @var{body} with @var{directory} as the process's current directory. Essentially, this macro changes the current directory to @var{directory} before evaluating @var{body}, using @code{chdir} (@pxref{Processes,,, guile, GNU Guile Reference Manual}). It changes back to the initial directory when the dynamic extent of @var{body} is left, be it @i{via} normal procedure return or @i{via} a non-local exit such as an exception. @end deffn @deffn {Scheme Procedure} mkdir-p @var{dir} Create directory @var{dir} and all its ancestors. @end deffn @deffn {Scheme Procedure} install-file @var{file} @var{directory} Create @var{directory} if it does not exist and copy @var{file} in there under the same name. @end deffn @deffn {Scheme Procedure} make-file-writable @var{file} Make @var{file} writable for its owner. @end deffn @deffn {Scheme Procedure} copy-recursively @var{source} @var{destination} @ [#:log (current-output-port)] [#:follow-symlinks? #f] [#:keep-mtime? #f] Copy @var{source} directory to @var{destination}. Follow symlinks if @var{follow-symlinks?} is true; otherwise, just preserve them. When @var{keep-mtime?} is true, keep the modification time of the files in @var{source} on those of @var{destination}. Write verbose output to the @var{log} port. @end deffn @deffn {Scheme Procedure} delete-file-recursively @var{dir} @ [#:follow-mounts? #f] Delete @var{dir} recursively, like @command{rm -rf}, without following symlinks. Don't follow mount points either, unless @var{follow-mounts?} is true. Report but ignore errors. @end deffn @deffn {Scheme Syntax} substitute* @var{file} @ ((@var{regexp} @var{match-var}@dots{}) @var{body}@dots{}) @dots{} Substitute @var{regexp} in @var{file} by the string returned by @var{body}. @var{body} is evaluated with each @var{match-var} bound to the corresponding positional regexp sub-expression. For example: @lisp (substitute* file (("hello") "good morning\n") (("foo([a-z]+)bar(.*)$" all letters end) (string-append "baz" letter end))) @end lisp Here, anytime a line of @var{file} contains @code{hello}, it is replaced by @code{good morning}. Anytime a line of @var{file} matches the second regexp, @code{all} is bound to the complete match, @code{letters} is bound to the first sub-expression, and @code{end} is bound to the last one. When one of the @var{match-var} is @code{_}, no variable is bound to the corresponding match substring. Alternatively, @var{file} may be a list of file names, in which case they are all subject to the substitutions. Be careful about using @code{$} to match the end of a line; by itself it won't match the terminating newline of a line. @end deffn @subsection File Search @cindex file, searching This section documents procedures to search and filter files. @deffn {Scheme Procedure} file-name-predicate @var{regexp} Return a predicate that returns true when passed a file name whose base name matches @var{regexp}. @end deffn @deffn {Scheme Procedure} find-files @var{dir} [@var{pred}] @ [#:stat lstat] [#:directories? #f] [#:fail-on-error? #f] Return the lexicographically sorted list of files under @var{dir} for which @var{pred} returns true. @var{pred} is passed two arguments: the absolute file name, and its stat buffer; the default predicate always returns true. @var{pred} can also be a regular expression, in which case it is equivalent to @code{(file-name-predicate @var{pred})}. @var{stat} is used to obtain file information; using @code{lstat} means that symlinks are not followed. If @var{directories?} is true, then directories will also be included. If @var{fail-on-error?} is true, raise an exception upon error. @end deffn Here are a few examples where we assume that the current directory is the root of the Guix source tree: @lisp ;; List all the regular files in the current directory. (find-files ".") @result{} ("./.dir-locals.el" "./.gitignore" @dots{}) ;; List all the .scm files under gnu/services. (find-files "gnu/services" "\\.scm$") @result{} ("gnu/services/admin.scm" "gnu/services/audio.scm" @dots{}) ;; List ar files in the current directory. (find-files "." (lambda (file stat) (ar-file? file))) @result{} ("./libformat.a" "./libstore.a" @dots{}) @end lisp @deffn {Scheme Procedure} which @var{program} Return the complete file name for @var{program} as found in @code{$PATH}, or @code{#f} if @var{program} could not be found. @end deffn @subsection Build Phases @cindex build phases The @code{(guix build utils)} also contains tools to manipulate build phases as used by build systems (@pxref{Build Systems}). Build phases are represented as association lists or ``alists'' (@pxref{Association Lists,,, guile, GNU Guile Reference Manual}) where each key is a symbol naming the phase and the associated value is a procedure (@pxref{Build Phases}). Guile core and the @code{(srfi srfi-1)} module both provide tools to manipulate alists. The @code{(guix build utils)} module complements those with tools written with build phases in mind. @cindex build phases, modifying @deffn {Scheme Syntax} modify-phases @var{phases} @var{clause}@dots{} Modify @var{phases} sequentially as per each @var{clause}, which may have one of the following forms: @lisp (delete @var{old-phase-name}) (replace @var{old-phase-name} @var{new-phase}) (add-before @var{old-phase-name} @var{new-phase-name} @var{new-phase}) (add-after @var{old-phase-name} @var{new-phase-name} @var{new-phase}) @end lisp Where every @var{phase-name} above is an expression evaluating to a symbol, and @var{new-phase} an expression evaluating to a procedure. @end deffn The example below is taken from the definition of the @code{grep} package. It adds a phase to run after the @code{install} phase, called @code{fix-egrep-and-fgrep}. That phase is a procedure (@code{lambda*} is for anonymous procedures) that takes a @code{#:outputs} keyword argument and ignores extra keyword arguments (@pxref{Optional Arguments,,, guile, GNU Guile Reference Manual}, for more on @code{lambda*} and optional and keyword arguments.) The phase uses @code{substitute*} to modify the installed @file{egrep} and @file{fgrep} scripts so that they refer to @code{grep} by its absolute file name: @lisp (modify-phases %standard-phases (add-after 'install 'fix-egrep-and-fgrep ;; Patch 'egrep' and 'fgrep' to execute 'grep' via its ;; absolute file name instead of searching for it in $PATH. (lambda* (#:key outputs #:allow-other-keys) (let* ((out (assoc-ref outputs "out")) (bin (string-append out "/bin"))) (substitute* (list (string-append bin "/egrep") (string-append bin "/fgrep")) (("^exec grep") (string-append "exec " bin "/grep"))) #t)))) @end lisp In the example below, phases are modified in two ways: the standard @code{configure} phase is deleted, presumably because the package does not have a @file{configure} script or anything similar, and the default @code{install} phase is replaced by one that manually copies the executable files to be installed: @lisp (modify-phases %standard-phases (delete 'configure) ;no 'configure' script (replace 'install (lambda* (#:key outputs #:allow-other-keys) ;; The package's Makefile doesn't provide an "install" ;; rule so do it by ourselves. (let ((bin (string-append (assoc-ref outputs "out") "/bin"))) (install-file "footswitch" bin) (install-file "scythe" bin) #t)))) @end lisp @c TODO: Add more examples. @node The Store @section The Store @cindex store @cindex store items @cindex store paths Conceptually, the @dfn{store} is the place where derivations that have been built successfully are stored---by default, @file{/gnu/store}. Sub-directories in the store are referred to as @dfn{store items} or sometimes @dfn{store paths}. The store has an associated database that contains information such as the store paths referred to by each store path, and the list of @emph{valid} store items---results of successful builds. This database resides in @file{@var{localstatedir}/guix/db}, where @var{localstatedir} is the state directory specified @i{via} @option{--localstatedir} at configure time, usually @file{/var}. The store is @emph{always} accessed by the daemon on behalf of its clients (@pxref{Invoking guix-daemon}). To manipulate the store, clients connect to the daemon over a Unix-domain socket, send requests to it, and read the result---these are remote procedure calls, or RPCs. @quotation Note Users must @emph{never} modify files under @file{/gnu/store} directly. This would lead to inconsistencies and break the immutability assumptions of Guix's functional model (@pxref{Introduction}). @xref{Invoking guix gc, @command{guix gc --verify}}, for information on how to check the integrity of the store and attempt recovery from accidental modifications. @end quotation The @code{(guix store)} module provides procedures to connect to the daemon, and to perform RPCs. These are described below. By default, @code{open-connection}, and thus all the @command{guix} commands, connect to the local daemon or to the URI specified by the @env{GUIX_DAEMON_SOCKET} environment variable. @defvr {Environment Variable} GUIX_DAEMON_SOCKET When set, the value of this variable should be a file name or a URI designating the daemon endpoint. When it is a file name, it denotes a Unix-domain socket to connect to. In addition to file names, the supported URI schemes are: @table @code @item file @itemx unix These are for Unix-domain sockets. @code{file:///var/guix/daemon-socket/socket} is equivalent to @file{/var/guix/daemon-socket/socket}. @item guix @cindex daemon, remote access @cindex remote access to the daemon @cindex daemon, cluster setup @cindex clusters, daemon setup These URIs denote connections over TCP/IP, without encryption nor authentication of the remote host. The URI must specify the host name and optionally a port number (by default port 44146 is used): @example guix://master.guix.example.org:1234 @end example This setup is suitable on local networks, such as clusters, where only trusted nodes may connect to the build daemon at @code{master.guix.example.org}. The @option{--listen} option of @command{guix-daemon} can be used to instruct it to listen for TCP connections (@pxref{Invoking guix-daemon, @option{--listen}}). @item ssh @cindex SSH access to build daemons These URIs allow you to connect to a remote daemon over SSH. This feature requires Guile-SSH (@pxref{Requirements}) and a working @command{guile} binary in @env{PATH} on the destination machine. It supports public key and GSSAPI authentication. A typical URL might look like this: @example ssh://charlie@@guix.example.org:22 @end example As for @command{guix copy}, the usual OpenSSH client configuration files are honored (@pxref{Invoking guix copy}). @end table Additional URI schemes may be supported in the future. @c XXX: Remove this note when the protocol incurs fewer round trips @c and when (guix derivations) no longer relies on file system access. @quotation Note The ability to connect to remote build daemons is considered experimental as of @value{VERSION}. Please get in touch with us to share any problems or suggestions you may have (@pxref{Contributing}). @end quotation @end defvr @deffn {Scheme Procedure} open-connection [@var{uri}] [#:reserve-space? #t] Connect to the daemon over the Unix-domain socket at @var{uri} (a string). When @var{reserve-space?} is true, instruct it to reserve a little bit of extra space on the file system so that the garbage collector can still operate should the disk become full. Return a server object. @var{file} defaults to @code{%default-socket-path}, which is the normal location given the options that were passed to @command{configure}. @end deffn @deffn {Scheme Procedure} close-connection @var{server} Close the connection to @var{server}. @end deffn @defvr {Scheme Variable} current-build-output-port This variable is bound to a SRFI-39 parameter, which refers to the port where build and error logs sent by the daemon should be written. @end defvr Procedures that make RPCs all take a server object as their first argument. @deffn {Scheme Procedure} valid-path? @var{server} @var{path} @cindex invalid store items Return @code{#t} when @var{path} designates a valid store item and @code{#f} otherwise (an invalid item may exist on disk but still be invalid, for instance because it is the result of an aborted or failed build). A @code{&store-protocol-error} condition is raised if @var{path} is not prefixed by the store directory (@file{/gnu/store}). @end deffn @deffn {Scheme Procedure} add-text-to-store @var{server} @var{name} @var{text} [@var{references}] Add @var{text} under file @var{name} in the store, and return its store path. @var{references} is the list of store paths referred to by the resulting store path. @end deffn @deffn {Scheme Procedure} build-derivations @var{store} @var{derivations} @ [@var{mode}] Build @var{derivations}, a list of @code{} objects, @file{.drv} file names, or derivation/output pairs, using the specified @var{mode}---@code{(build-mode normal)} by default. @end deffn Note that the @code{(guix monads)} module provides a monad as well as monadic versions of the above procedures, with the goal of making it more convenient to work with code that accesses the store (@pxref{The Store Monad}). @c FIXME @i{This section is currently incomplete.} @node Derivations @section Derivations @cindex derivations Low-level build actions and the environment in which they are performed are represented by @dfn{derivations}. A derivation contains the following pieces of information: @itemize @item The outputs of the derivation---derivations produce at least one file or directory in the store, but may produce more. @item @cindex build-time dependencies @cindex dependencies, build-time The inputs of the derivations---i.e., its build-time dependencies---which may be other derivations or plain files in the store (patches, build scripts, etc.). @item The system type targeted by the derivation---e.g., @code{x86_64-linux}. @item The file name of a build script in the store, along with the arguments to be passed. @item A list of environment variables to be defined. @end itemize @cindex derivation path Derivations allow clients of the daemon to communicate build actions to the store. They exist in two forms: as an in-memory representation, both on the client- and daemon-side, and as files in the store whose name end in @file{.drv}---these files are referred to as @dfn{derivation paths}. Derivations paths can be passed to the @code{build-derivations} procedure to perform the build actions they prescribe (@pxref{The Store}). @cindex fixed-output derivations Operations such as file downloads and version-control checkouts for which the expected content hash is known in advance are modeled as @dfn{fixed-output derivations}. Unlike regular derivations, the outputs of a fixed-output derivation are independent of its inputs---e.g., a source code download produces the same result regardless of the download method and tools being used. @cindex references @cindex run-time dependencies @cindex dependencies, run-time The outputs of derivations---i.e., the build results---have a set of @dfn{references}, as reported by the @code{references} RPC or the @command{guix gc --references} command (@pxref{Invoking guix gc}). References are the set of run-time dependencies of the build results. References are a subset of the inputs of the derivation; this subset is automatically computed by the build daemon by scanning all the files in the outputs. The @code{(guix derivations)} module provides a representation of derivations as Scheme objects, along with procedures to create and otherwise manipulate derivations. The lowest-level primitive to create a derivation is the @code{derivation} procedure: @deffn {Scheme Procedure} derivation @var{store} @var{name} @var{builder} @ @var{args} [#:outputs '("out")] [#:hash #f] [#:hash-algo #f] @ [#:recursive? #f] [#:inputs '()] [#:env-vars '()] @ [#:system (%current-system)] [#:references-graphs #f] @ [#:allowed-references #f] [#:disallowed-references #f] @ [#:leaked-env-vars #f] [#:local-build? #f] @ [#:substitutable? #t] [#:properties '()] Build a derivation with the given arguments, and return the resulting @code{} object. When @var{hash} and @var{hash-algo} are given, a @dfn{fixed-output derivation} is created---i.e., one whose result is known in advance, such as a file download. If, in addition, @var{recursive?} is true, then that fixed output may be an executable file or a directory and @var{hash} must be the hash of an archive containing this output. When @var{references-graphs} is true, it must be a list of file name/store path pairs. In that case, the reference graph of each store path is exported in the build environment in the corresponding file, in a simple text format. When @var{allowed-references} is true, it must be a list of store items or outputs that the derivation's output may refer to. Likewise, @var{disallowed-references}, if true, must be a list of things the outputs may @emph{not} refer to. When @var{leaked-env-vars} is true, it must be a list of strings denoting environment variables that are allowed to ``leak'' from the daemon's environment to the build environment. This is only applicable to fixed-output derivations---i.e., when @var{hash} is true. The main use is to allow variables such as @code{http_proxy} to be passed to derivations that download files. When @var{local-build?} is true, declare that the derivation is not a good candidate for offloading and should rather be built locally (@pxref{Daemon Offload Setup}). This is the case for small derivations where the costs of data transfers would outweigh the benefits. When @var{substitutable?} is false, declare that substitutes of the derivation's output should not be used (@pxref{Substitutes}). This is useful, for instance, when building packages that capture details of the host CPU instruction set. @var{properties} must be an association list describing ``properties'' of the derivation. It is kept as-is, uninterpreted, in the derivation. @end deffn @noindent Here's an example with a shell script as its builder, assuming @var{store} is an open connection to the daemon, and @var{bash} points to a Bash executable in the store: @lisp (use-modules (guix utils) (guix store) (guix derivations)) (let ((builder ; add the Bash script to the store (add-text-to-store store "my-builder.sh" "echo hello world > $out\n" '()))) (derivation store "foo" bash `("-e" ,builder) #:inputs `((,bash) (,builder)) #:env-vars '(("HOME" . "/homeless")))) @result{} # /gnu/store/@dots{}-foo> @end lisp As can be guessed, this primitive is cumbersome to use directly. A better approach is to write build scripts in Scheme, of course! The best course of action for that is to write the build code as a ``G-expression'', and to pass it to @code{gexp->derivation}. For more information, @pxref{G-Expressions}. Once upon a time, @code{gexp->derivation} did not exist and constructing derivations with build code written in Scheme was achieved with @code{build-expression->derivation}, documented below. This procedure is now deprecated in favor of the much nicer @code{gexp->derivation}. @deffn {Scheme Procedure} build-expression->derivation @var{store} @ @var{name} @var{exp} @ [#:system (%current-system)] [#:inputs '()] @ [#:outputs '("out")] [#:hash #f] [#:hash-algo #f] @ [#:recursive? #f] [#:env-vars '()] [#:modules '()] @ [#:references-graphs #f] [#:allowed-references #f] @ [#:disallowed-references #f] @ [#:local-build? #f] [#:substitutable? #t] [#:guile-for-build #f] Return a derivation that executes Scheme expression @var{exp} as a builder for derivation @var{name}. @var{inputs} must be a list of @code{(name drv-path sub-drv)} tuples; when @var{sub-drv} is omitted, @code{"out"} is assumed. @var{modules} is a list of names of Guile modules from the current search path to be copied in the store, compiled, and made available in the load path during the execution of @var{exp}---e.g., @code{((guix build utils) (guix build gnu-build-system))}. @var{exp} is evaluated in an environment where @code{%outputs} is bound to a list of output/path pairs, and where @code{%build-inputs} is bound to a list of string/output-path pairs made from @var{inputs}. Optionally, @var{env-vars} is a list of string pairs specifying the name and value of environment variables visible to the builder. The builder terminates by passing the result of @var{exp} to @code{exit}; thus, when @var{exp} returns @code{#f}, the build is considered to have failed. @var{exp} is built using @var{guile-for-build} (a derivation). When @var{guile-for-build} is omitted or is @code{#f}, the value of the @code{%guile-for-build} fluid is used instead. See the @code{derivation} procedure for the meaning of @var{references-graphs}, @var{allowed-references}, @var{disallowed-references}, @var{local-build?}, and @var{substitutable?}. @end deffn @noindent Here's an example of a single-output derivation that creates a directory containing one file: @lisp (let ((builder '(let ((out (assoc-ref %outputs "out"))) (mkdir out) ; create /gnu/store/@dots{}-goo (call-with-output-file (string-append out "/test") (lambda (p) (display '(hello guix) p)))))) (build-expression->derivation store "goo" builder)) @result{} # @dots{}> @end lisp @node The Store Monad @section The Store Monad @cindex monad The procedures that operate on the store described in the previous sections all take an open connection to the build daemon as their first argument. Although the underlying model is functional, they either have side effects or depend on the current state of the store. The former is inconvenient: the connection to the build daemon has to be carried around in all those functions, making it impossible to compose functions that do not take that parameter with functions that do. The latter can be problematic: since store operations have side effects and/or depend on external state, they have to be properly sequenced. @cindex monadic values @cindex monadic functions This is where the @code{(guix monads)} module comes in. This module provides a framework for working with @dfn{monads}, and a particularly useful monad for our uses, the @dfn{store monad}. Monads are a construct that allows two things: associating ``context'' with values (in our case, the context is the store), and building sequences of computations (here computations include accesses to the store). Values in a monad---values that carry this additional context---are called @dfn{monadic values}; procedures that return such values are called @dfn{monadic procedures}. Consider this ``normal'' procedure: @lisp (define (sh-symlink store) ;; Return a derivation that symlinks the 'bash' executable. (let* ((drv (package-derivation store bash)) (out (derivation->output-path drv)) (sh (string-append out "/bin/bash"))) (build-expression->derivation store "sh" `(symlink ,sh %output)))) @end lisp Using @code{(guix monads)} and @code{(guix gexp)}, it may be rewritten as a monadic function: @lisp (define (sh-symlink) ;; Same, but return a monadic value. (mlet %store-monad ((drv (package->derivation bash))) (gexp->derivation "sh" #~(symlink (string-append #$drv "/bin/bash") #$output)))) @end lisp There are several things to note in the second version: the @code{store} parameter is now implicit and is ``threaded'' in the calls to the @code{package->derivation} and @code{gexp->derivation} monadic procedures, and the monadic value returned by @code{package->derivation} is @dfn{bound} using @code{mlet} instead of plain @code{let}. As it turns out, the call to @code{package->derivation} can even be omitted since it will take place implicitly, as we will see later (@pxref{G-Expressions}): @lisp (define (sh-symlink) (gexp->derivation "sh" #~(symlink (string-append #$bash "/bin/bash") #$output))) @end lisp @c See @c @c for the funny quote. Calling the monadic @code{sh-symlink} has no effect. As someone once said, ``you exit a monad like you exit a building on fire: by running''. So, to exit the monad and get the desired effect, one must use @code{run-with-store}: @lisp (run-with-store (open-connection) (sh-symlink)) @result{} /gnu/store/...-sh-symlink @end lisp Note that the @code{(guix monad-repl)} module extends the Guile REPL with new ``meta-commands'' to make it easier to deal with monadic procedures: @code{run-in-store}, and @code{enter-store-monad}. The former is used to ``run'' a single monadic value through the store: @example scheme@@(guile-user)> ,run-in-store (package->derivation hello) $1 = # @dots{}> @end example The latter enters a recursive REPL, where all the return values are automatically run through the store: @example scheme@@(guile-user)> ,enter-store-monad store-monad@@(guile-user) [1]> (package->derivation hello) $2 = # @dots{}> store-monad@@(guile-user) [1]> (text-file "foo" "Hello!") $3 = "/gnu/store/@dots{}-foo" store-monad@@(guile-user) [1]> ,q scheme@@(guile-user)> @end example @noindent Note that non-monadic values cannot be returned in the @code{store-monad} REPL. The main syntactic forms to deal with monads in general are provided by the @code{(guix monads)} module and are described below. @deffn {Scheme Syntax} with-monad @var{monad} @var{body} ... Evaluate any @code{>>=} or @code{return} forms in @var{body} as being in @var{monad}. @end deffn @deffn {Scheme Syntax} return @var{val} Return a monadic value that encapsulates @var{val}. @end deffn @deffn {Scheme Syntax} >>= @var{mval} @var{mproc} ... @dfn{Bind} monadic value @var{mval}, passing its ``contents'' to monadic procedures @var{mproc}@dots{}@footnote{This operation is commonly referred to as ``bind'', but that name denotes an unrelated procedure in Guile. Thus we use this somewhat cryptic symbol inherited from the Haskell language.}. There can be one @var{mproc} or several of them, as in this example: @lisp (run-with-state (with-monad %state-monad (>>= (return 1) (lambda (x) (return (+ 1 x))) (lambda (x) (return (* 2 x))))) 'some-state) @result{} 4 @result{} some-state @end lisp @end deffn @deffn {Scheme Syntax} mlet @var{monad} ((@var{var} @var{mval}) ...) @ @var{body} ... @deffnx {Scheme Syntax} mlet* @var{monad} ((@var{var} @var{mval}) ...) @ @var{body} ... Bind the variables @var{var} to the monadic values @var{mval} in @var{body}, which is a sequence of expressions. As with the bind operator, this can be thought of as ``unpacking'' the raw, non-monadic value ``contained'' in @var{mval} and making @var{var} refer to that raw, non-monadic value within the scope of the @var{body}. The form (@var{var} -> @var{val}) binds @var{var} to the ``normal'' value @var{val}, as per @code{let}. The binding operations occur in sequence from left to right. The last expression of @var{body} must be a monadic expression, and its result will become the result of the @code{mlet} or @code{mlet*} when run in the @var{monad}. @code{mlet*} is to @code{mlet} what @code{let*} is to @code{let} (@pxref{Local Bindings,,, guile, GNU Guile Reference Manual}). @end deffn @deffn {Scheme System} mbegin @var{monad} @var{mexp} ... Bind @var{mexp} and the following monadic expressions in sequence, returning the result of the last expression. Every expression in the sequence must be a monadic expression. This is akin to @code{mlet}, except that the return values of the monadic expressions are ignored. In that sense, it is analogous to @code{begin}, but applied to monadic expressions. @end deffn @deffn {Scheme System} mwhen @var{condition} @var{mexp0} @var{mexp*} ... When @var{condition} is true, evaluate the sequence of monadic expressions @var{mexp0}..@var{mexp*} as in an @code{mbegin}. When @var{condition} is false, return @code{*unspecified*} in the current monad. Every expression in the sequence must be a monadic expression. @end deffn @deffn {Scheme System} munless @var{condition} @var{mexp0} @var{mexp*} ... When @var{condition} is false, evaluate the sequence of monadic expressions @var{mexp0}..@var{mexp*} as in an @code{mbegin}. When @var{condition} is true, return @code{*unspecified*} in the current monad. Every expression in the sequence must be a monadic expression. @end deffn @cindex state monad The @code{(guix monads)} module provides the @dfn{state monad}, which allows an additional value---the state---to be @emph{threaded} through monadic procedure calls. @defvr {Scheme Variable} %state-monad The state monad. Procedures in the state monad can access and change the state that is threaded. Consider the example below. The @code{square} procedure returns a value in the state monad. It returns the square of its argument, but also increments the current state value: @lisp (define (square x) (mlet %state-monad ((count (current-state))) (mbegin %state-monad (set-current-state (+ 1 count)) (return (* x x))))) (run-with-state (sequence %state-monad (map square (iota 3))) 0) @result{} (0 1 4) @result{} 3 @end lisp When ``run'' through @code{%state-monad}, we obtain that additional state value, which is the number of @code{square} calls. @end defvr @deffn {Monadic Procedure} current-state Return the current state as a monadic value. @end deffn @deffn {Monadic Procedure} set-current-state @var{value} Set the current state to @var{value} and return the previous state as a monadic value. @end deffn @deffn {Monadic Procedure} state-push @var{value} Push @var{value} to the current state, which is assumed to be a list, and return the previous state as a monadic value. @end deffn @deffn {Monadic Procedure} state-pop Pop a value from the current state and return it as a monadic value. The state is assumed to be a list. @end deffn @deffn {Scheme Procedure} run-with-state @var{mval} [@var{state}] Run monadic value @var{mval} starting with @var{state} as the initial state. Return two values: the resulting value, and the resulting state. @end deffn The main interface to the store monad, provided by the @code{(guix store)} module, is as follows. @defvr {Scheme Variable} %store-monad The store monad---an alias for @code{%state-monad}. Values in the store monad encapsulate accesses to the store. When its effect is needed, a value of the store monad must be ``evaluated'' by passing it to the @code{run-with-store} procedure (see below). @end defvr @deffn {Scheme Procedure} run-with-store @var{store} @var{mval} [#:guile-for-build] [#:system (%current-system)] Run @var{mval}, a monadic value in the store monad, in @var{store}, an open store connection. @end deffn @deffn {Monadic Procedure} text-file @var{name} @var{text} [@var{references}] Return as a monadic value the absolute file name in the store of the file containing @var{text}, a string. @var{references} is a list of store items that the resulting text file refers to; it defaults to the empty list. @end deffn @deffn {Monadic Procedure} binary-file @var{name} @var{data} [@var{references}] Return as a monadic value the absolute file name in the store of the file containing @var{data}, a bytevector. @var{references} is a list of store items that the resulting binary file refers to; it defaults to the empty list. @end deffn @deffn {Monadic Procedure} interned-file @var{file} [@var{name}] @ [#:recursive? #t] [#:select? (const #t)] Return the name of @var{file} once interned in the store. Use @var{name} as its store name, or the basename of @var{file} if @var{name} is omitted. When @var{recursive?} is true, the contents of @var{file} are added recursively; if @var{file} designates a flat file and @var{recursive?} is true, its contents are added, and its permission bits are kept. When @var{recursive?} is true, call @code{(@var{select?} @var{file} @var{stat})} for each directory entry, where @var{file} is the entry's absolute file name and @var{stat} is the result of @code{lstat}; exclude entries for which @var{select?} does not return true. The example below adds a file to the store, under two different names: @lisp (run-with-store (open-connection) (mlet %store-monad ((a (interned-file "README")) (b (interned-file "README" "LEGU-MIN"))) (return (list a b)))) @result{} ("/gnu/store/rwm@dots{}-README" "/gnu/store/44i@dots{}-LEGU-MIN") @end lisp @end deffn The @code{(guix packages)} module exports the following package-related monadic procedures: @deffn {Monadic Procedure} package-file @var{package} [@var{file}] @ [#:system (%current-system)] [#:target #f] @ [#:output "out"] Return as a monadic value in the absolute file name of @var{file} within the @var{output} directory of @var{package}. When @var{file} is omitted, return the name of the @var{output} directory of @var{package}. When @var{target} is true, use it as a cross-compilation target triplet. Note that this procedure does @emph{not} build @var{package}. Thus, the result might or might not designate an existing file. We recommend not using this procedure unless you know what you are doing. @end deffn @deffn {Monadic Procedure} package->derivation @var{package} [@var{system}] @deffnx {Monadic Procedure} package->cross-derivation @var{package} @ @var{target} [@var{system}] Monadic version of @code{package-derivation} and @code{package-cross-derivation} (@pxref{Defining Packages}). @end deffn @node G-Expressions @section G-Expressions @cindex G-expression @cindex build code quoting So we have ``derivations'', which represent a sequence of build actions to be performed to produce an item in the store (@pxref{Derivations}). These build actions are performed when asking the daemon to actually build the derivations; they are run by the daemon in a container (@pxref{Invoking guix-daemon}). @cindex code staging @cindex staging, of code @cindex strata of code It should come as no surprise that we like to write these build actions in Scheme. When we do that, we end up with two @dfn{strata} of Scheme code@footnote{The term @dfn{stratum} in this context was coined by Manuel Serrano et al.@: in the context of their work on Hop. Oleg Kiselyov, who has written insightful @url{http://okmij.org/ftp/meta-programming/#meta-scheme, essays and code on this topic}, refers to this kind of code generation as @dfn{staging}.}: the ``host code''---code that defines packages, talks to the daemon, etc.---and the ``build code''---code that actually performs build actions, such as making directories, invoking @command{make}, and so on (@pxref{Build Phases}). To describe a derivation and its build actions, one typically needs to embed build code inside host code. It boils down to manipulating build code as data, and the homoiconicity of Scheme---code has a direct representation as data---comes in handy for that. But we need more than the normal @code{quasiquote} mechanism in Scheme to construct build expressions. The @code{(guix gexp)} module implements @dfn{G-expressions}, a form of S-expressions adapted to build expressions. G-expressions, or @dfn{gexps}, consist essentially of three syntactic forms: @code{gexp}, @code{ungexp}, and @code{ungexp-splicing} (or simply: @code{#~}, @code{#$}, and @code{#$@@}), which are comparable to @code{quasiquote}, @code{unquote}, and @code{unquote-splicing}, respectively (@pxref{Expression Syntax, @code{quasiquote},, guile, GNU Guile Reference Manual}). However, there are major differences: @itemize @item Gexps are meant to be written to a file and run or manipulated by other processes. @item When a high-level object such as a package or derivation is unquoted inside a gexp, the result is as if its output file name had been introduced. @item Gexps carry information about the packages or derivations they refer to, and these dependencies are automatically added as inputs to the build processes that use them. @end itemize @cindex lowering, of high-level objects in gexps This mechanism is not limited to package and derivation objects: @dfn{compilers} able to ``lower'' other high-level objects to derivations or files in the store can be defined, such that these objects can also be inserted into gexps. For example, a useful type of high-level objects that can be inserted in a gexp is ``file-like objects'', which make it easy to add files to the store and to refer to them in derivations and such (see @code{local-file} and @code{plain-file} below). To illustrate the idea, here is an example of a gexp: @lisp (define build-exp #~(begin (mkdir #$output) (chdir #$output) (symlink (string-append #$coreutils "/bin/ls") "list-files"))) @end lisp This gexp can be passed to @code{gexp->derivation}; we obtain a derivation that builds a directory containing exactly one symlink to @file{/gnu/store/@dots{}-coreutils-8.22/bin/ls}: @lisp (gexp->derivation "the-thing" build-exp) @end lisp As one would expect, the @code{"/gnu/store/@dots{}-coreutils-8.22"} string is substituted to the reference to the @var{coreutils} package in the actual build code, and @var{coreutils} is automatically made an input to the derivation. Likewise, @code{#$output} (equivalent to @code{(ungexp output)}) is replaced by a string containing the directory name of the output of the derivation. @cindex cross compilation In a cross-compilation context, it is useful to distinguish between references to the @emph{native} build of a package---that can run on the host---versus references to cross builds of a package. To that end, the @code{#+} plays the same role as @code{#$}, but is a reference to a native package build: @lisp (gexp->derivation "vi" #~(begin (mkdir #$output) (mkdir (string-append #$output "/bin")) (system* (string-append #+coreutils "/bin/ln") "-s" (string-append #$emacs "/bin/emacs") (string-append #$output "/bin/vi"))) #:target "aarch64-linux-gnu") @end lisp @noindent In the example above, the native build of @var{coreutils} is used, so that @command{ln} can actually run on the host; but then the cross-compiled build of @var{emacs} is referenced. @cindex imported modules, for gexps @findex with-imported-modules Another gexp feature is @dfn{imported modules}: sometimes you want to be able to use certain Guile modules from the ``host environment'' in the gexp, so those modules should be imported in the ``build environment''. The @code{with-imported-modules} form allows you to express that: @lisp (let ((build (with-imported-modules '((guix build utils)) #~(begin (use-modules (guix build utils)) (mkdir-p (string-append #$output "/bin")))))) (gexp->derivation "empty-dir" #~(begin #$build (display "success!\n") #t))) @end lisp @noindent In this example, the @code{(guix build utils)} module is automatically pulled into the isolated build environment of our gexp, such that @code{(use-modules (guix build utils))} works as expected. @cindex module closure @findex source-module-closure Usually you want the @emph{closure} of the module to be imported---i.e., the module itself and all the modules it depends on---rather than just the module; failing to do that, attempts to use the module will fail because of missing dependent modules. The @code{source-module-closure} procedure computes the closure of a module by looking at its source file headers, which comes in handy in this case: @lisp (use-modules (guix modules)) ;for 'source-module-closure' (with-imported-modules (source-module-closure '((guix build utils) (gnu build vm))) (gexp->derivation "something-with-vms" #~(begin (use-modules (guix build utils) (gnu build vm)) @dots{}))) @end lisp @cindex extensions, for gexps @findex with-extensions In the same vein, sometimes you want to import not just pure-Scheme modules, but also ``extensions'' such as Guile bindings to C libraries or other ``full-blown'' packages. Say you need the @code{guile-json} package available on the build side, here's how you would do it: @lisp (use-modules (gnu packages guile)) ;for 'guile-json' (with-extensions (list guile-json) (gexp->derivation "something-with-json" #~(begin (use-modules (json)) @dots{}))) @end lisp The syntactic form to construct gexps is summarized below. @deffn {Scheme Syntax} #~@var{exp} @deffnx {Scheme Syntax} (gexp @var{exp}) Return a G-expression containing @var{exp}. @var{exp} may contain one or more of the following forms: @table @code @item #$@var{obj} @itemx (ungexp @var{obj}) Introduce a reference to @var{obj}. @var{obj} may have one of the supported types, for example a package or a derivation, in which case the @code{ungexp} form is replaced by its output file name---e.g., @code{"/gnu/store/@dots{}-coreutils-8.22}. If @var{obj} is a list, it is traversed and references to supported objects are substituted similarly. If @var{obj} is another gexp, its contents are inserted and its dependencies are added to those of the containing gexp. If @var{obj} is another kind of object, it is inserted as is. @item #$@var{obj}:@var{output} @itemx (ungexp @var{obj} @var{output}) This is like the form above, but referring explicitly to the @var{output} of @var{obj}---this is useful when @var{obj} produces multiple outputs (@pxref{Packages with Multiple Outputs}). @item #+@var{obj} @itemx #+@var{obj}:output @itemx (ungexp-native @var{obj}) @itemx (ungexp-native @var{obj} @var{output}) Same as @code{ungexp}, but produces a reference to the @emph{native} build of @var{obj} when used in a cross compilation context. @item #$output[:@var{output}] @itemx (ungexp output [@var{output}]) Insert a reference to derivation output @var{output}, or to the main output when @var{output} is omitted. This only makes sense for gexps passed to @code{gexp->derivation}. @item #$@@@var{lst} @itemx (ungexp-splicing @var{lst}) Like the above, but splices the contents of @var{lst} inside the containing list. @item #+@@@var{lst} @itemx (ungexp-native-splicing @var{lst}) Like the above, but refers to native builds of the objects listed in @var{lst}. @end table G-expressions created by @code{gexp} or @code{#~} are run-time objects of the @code{gexp?} type (see below). @end deffn @deffn {Scheme Syntax} with-imported-modules @var{modules} @var{body}@dots{} Mark the gexps defined in @var{body}@dots{} as requiring @var{modules} in their execution environment. Each item in @var{modules} can be the name of a module, such as @code{(guix build utils)}, or it can be a module name, followed by an arrow, followed by a file-like object: @lisp `((guix build utils) (guix gcrypt) ((guix config) => ,(scheme-file "config.scm" #~(define-module @dots{})))) @end lisp @noindent In the example above, the first two modules are taken from the search path, and the last one is created from the given file-like object. This form has @emph{lexical} scope: it has an effect on the gexps directly defined in @var{body}@dots{}, but not on those defined, say, in procedures called from @var{body}@dots{}. @end deffn @deffn {Scheme Syntax} with-extensions @var{extensions} @var{body}@dots{} Mark the gexps defined in @var{body}@dots{} as requiring @var{extensions} in their build and execution environment. @var{extensions} is typically a list of package objects such as those defined in the @code{(gnu packages guile)} module. Concretely, the packages listed in @var{extensions} are added to the load path while compiling imported modules in @var{body}@dots{}; they are also added to the load path of the gexp returned by @var{body}@dots{}. @end deffn @deffn {Scheme Procedure} gexp? @var{obj} Return @code{#t} if @var{obj} is a G-expression. @end deffn G-expressions are meant to be written to disk, either as code building some derivation, or as plain files in the store. The monadic procedures below allow you to do that (@pxref{The Store Monad}, for more information about monads). @deffn {Monadic Procedure} gexp->derivation @var{name} @var{exp} @ [#:system (%current-system)] [#:target #f] [#:graft? #t] @ [#:hash #f] [#:hash-algo #f] @ [#:recursive? #f] [#:env-vars '()] [#:modules '()] @ [#:module-path @code{%load-path}] @ [#:effective-version "2.2"] @ [#:references-graphs #f] [#:allowed-references #f] @ [#:disallowed-references #f] @ [#:leaked-env-vars #f] @ [#:script-name (string-append @var{name} "-builder")] @ [#:deprecation-warnings #f] @ [#:local-build? #f] [#:substitutable? #t] @ [#:properties '()] [#:guile-for-build #f] Return a derivation @var{name} that runs @var{exp} (a gexp) with @var{guile-for-build} (a derivation) on @var{system}; @var{exp} is stored in a file called @var{script-name}. When @var{target} is true, it is used as the cross-compilation target triplet for packages referred to by @var{exp}. @var{modules} is deprecated in favor of @code{with-imported-modules}. Its meaning is to make @var{modules} available in the evaluation context of @var{exp}; @var{modules} is a list of names of Guile modules searched in @var{module-path} to be copied in the store, compiled, and made available in the load path during the execution of @var{exp}---e.g., @code{((guix build utils) (guix build gnu-build-system))}. @var{effective-version} determines the string to use when adding extensions of @var{exp} (see @code{with-extensions}) to the search path---e.g., @code{"2.2"}. @var{graft?} determines whether packages referred to by @var{exp} should be grafted when applicable. When @var{references-graphs} is true, it must be a list of tuples of one of the following forms: @example (@var{file-name} @var{package}) (@var{file-name} @var{package} @var{output}) (@var{file-name} @var{derivation}) (@var{file-name} @var{derivation} @var{output}) (@var{file-name} @var{store-item}) @end example The right-hand-side of each element of @var{references-graphs} is automatically made an input of the build process of @var{exp}. In the build environment, each @var{file-name} contains the reference graph of the corresponding item, in a simple text format. @var{allowed-references} must be either @code{#f} or a list of output names and packages. In the latter case, the list denotes store items that the result is allowed to refer to. Any reference to another store item will lead to a build error. Similarly for @var{disallowed-references}, which can list items that must not be referenced by the outputs. @var{deprecation-warnings} determines whether to show deprecation warnings while compiling modules. It can be @code{#f}, @code{#t}, or @code{'detailed}. The other arguments are as for @code{derivation} (@pxref{Derivations}). @end deffn @cindex file-like objects The @code{local-file}, @code{plain-file}, @code{computed-file}, @code{program-file}, and @code{scheme-file} procedures below return @dfn{file-like objects}. That is, when unquoted in a G-expression, these objects lead to a file in the store. Consider this G-expression: @lisp #~(system* #$(file-append glibc "/sbin/nscd") "-f" #$(local-file "/tmp/my-nscd.conf")) @end lisp The effect here is to ``intern'' @file{/tmp/my-nscd.conf} by copying it to the store. Once expanded, for instance @i{via} @code{gexp->derivation}, the G-expression refers to that copy under @file{/gnu/store}; thus, modifying or removing the file in @file{/tmp} does not have any effect on what the G-expression does. @code{plain-file} can be used similarly; it differs in that the file content is directly passed as a string. @deffn {Scheme Procedure} local-file @var{file} [@var{name}] @ [#:recursive? #f] [#:select? (const #t)] Return an object representing local file @var{file} to add to the store; this object can be used in a gexp. If @var{file} is a literal string denoting a relative file name, it is looked up relative to the source file where it appears; if @var{file} is not a literal string, it is looked up relative to the current working directory at run time. @var{file} will be added to the store under @var{name}--by default the base name of @var{file}. When @var{recursive?} is true, the contents of @var{file} are added recursively; if @var{file} designates a flat file and @var{recursive?} is true, its contents are added, and its permission bits are kept. When @var{recursive?} is true, call @code{(@var{select?} @var{file} @var{stat})} for each directory entry, where @var{file} is the entry's absolute file name and @var{stat} is the result of @code{lstat}; exclude entries for which @var{select?} does not return true. This is the declarative counterpart of the @code{interned-file} monadic procedure (@pxref{The Store Monad, @code{interned-file}}). @end deffn @deffn {Scheme Procedure} plain-file @var{name} @var{content} Return an object representing a text file called @var{name} with the given @var{content} (a string or a bytevector) to be added to the store. This is the declarative counterpart of @code{text-file}. @end deffn @deffn {Scheme Procedure} computed-file @var{name} @var{gexp} @ [#:local-build? #t] [#:options '()] Return an object representing the store item @var{name}, a file or directory computed by @var{gexp}. When @var{local-build?} is true (the default), the derivation is built locally. @var{options} is a list of additional arguments to pass to @code{gexp->derivation}. This is the declarative counterpart of @code{gexp->derivation}. @end deffn @deffn {Monadic Procedure} gexp->script @var{name} @var{exp} @ [#:guile (default-guile)] [#:module-path %load-path] @ [#:system (%current-system)] [#:target #f] Return an executable script @var{name} that runs @var{exp} using @var{guile}, with @var{exp}'s imported modules in its search path. Look up @var{exp}'s modules in @var{module-path}. The example below builds a script that simply invokes the @command{ls} command: @lisp (use-modules (guix gexp) (gnu packages base)) (gexp->script "list-files" #~(execl #$(file-append coreutils "/bin/ls") "ls")) @end lisp When ``running'' it through the store (@pxref{The Store Monad, @code{run-with-store}}), we obtain a derivation that produces an executable file @file{/gnu/store/@dots{}-list-files} along these lines: @example #!/gnu/store/@dots{}-guile-2.0.11/bin/guile -ds !# (execl "/gnu/store/@dots{}-coreutils-8.22"/bin/ls" "ls") @end example @end deffn @deffn {Scheme Procedure} program-file @var{name} @var{exp} @ [#:guile #f] [#:module-path %load-path] Return an object representing the executable store item @var{name} that runs @var{gexp}. @var{guile} is the Guile package used to execute that script. Imported modules of @var{gexp} are looked up in @var{module-path}. This is the declarative counterpart of @code{gexp->script}. @end deffn @deffn {Monadic Procedure} gexp->file @var{name} @var{exp} @ [#:set-load-path? #t] [#:module-path %load-path] @ [#:splice? #f] @ [#:guile (default-guile)] Return a derivation that builds a file @var{name} containing @var{exp}. When @var{splice?} is true, @var{exp} is considered to be a list of expressions that will be spliced in the resulting file. When @var{set-load-path?} is true, emit code in the resulting file to set @code{%load-path} and @code{%load-compiled-path} to honor @var{exp}'s imported modules. Look up @var{exp}'s modules in @var{module-path}. The resulting file holds references to all the dependencies of @var{exp} or a subset thereof. @end deffn @deffn {Scheme Procedure} scheme-file @var{name} @var{exp} @ [#:splice? #f] [#:set-load-path? #t] Return an object representing the Scheme file @var{name} that contains @var{exp}. This is the declarative counterpart of @code{gexp->file}. @end deffn @deffn {Monadic Procedure} text-file* @var{name} @var{text} @dots{} Return as a monadic value a derivation that builds a text file containing all of @var{text}. @var{text} may list, in addition to strings, objects of any type that can be used in a gexp: packages, derivations, local file objects, etc. The resulting store file holds references to all these. This variant should be preferred over @code{text-file} anytime the file to create will reference items from the store. This is typically the case when building a configuration file that embeds store file names, like this: @lisp (define (profile.sh) ;; Return the name of a shell script in the store that ;; initializes the 'PATH' environment variable. (text-file* "profile.sh" "export PATH=" coreutils "/bin:" grep "/bin:" sed "/bin\n")) @end lisp In this example, the resulting @file{/gnu/store/@dots{}-profile.sh} file will reference @var{coreutils}, @var{grep}, and @var{sed}, thereby preventing them from being garbage-collected during its lifetime. @end deffn @deffn {Scheme Procedure} mixed-text-file @var{name} @var{text} @dots{} Return an object representing store file @var{name} containing @var{text}. @var{text} is a sequence of strings and file-like objects, as in: @lisp (mixed-text-file "profile" "export PATH=" coreutils "/bin:" grep "/bin") @end lisp This is the declarative counterpart of @code{text-file*}. @end deffn @deffn {Scheme Procedure} file-union @var{name} @var{files} Return a @code{} that builds a directory containing all of @var{files}. Each item in @var{files} must be a two-element list where the first element is the file name to use in the new directory, and the second element is a gexp denoting the target file. Here's an example: @lisp (file-union "etc" `(("hosts" ,(plain-file "hosts" "127.0.0.1 localhost")) ("bashrc" ,(plain-file "bashrc" "alias ls='ls --color=auto'")))) @end lisp This yields an @code{etc} directory containing these two files. @end deffn @deffn {Scheme Procedure} directory-union @var{name} @var{things} Return a directory that is the union of @var{things}, where @var{things} is a list of file-like objects denoting directories. For example: @lisp (directory-union "guile+emacs" (list guile emacs)) @end lisp yields a directory that is the union of the @code{guile} and @code{emacs} packages. @end deffn @deffn {Scheme Procedure} file-append @var{obj} @var{suffix} @dots{} Return a file-like object that expands to the concatenation of @var{obj} and @var{suffix}, where @var{obj} is a lowerable object and each @var{suffix} is a string. As an example, consider this gexp: @lisp (gexp->script "run-uname" #~(system* #$(file-append coreutils "/bin/uname"))) @end lisp The same effect could be achieved with: @lisp (gexp->script "run-uname" #~(system* (string-append #$coreutils "/bin/uname"))) @end lisp There is one difference though: in the @code{file-append} case, the resulting script contains the absolute file name as a string, whereas in the second case, the resulting script contains a @code{(string-append @dots{})} expression to construct the file name @emph{at run time}. @end deffn @deffn {Scheme Syntax} let-system @var{system} @var{body}@dots{} @deffnx {Scheme Syntax} let-system (@var{system} @var{target}) @var{body}@dots{} Bind @var{system} to the currently targeted system---e.g., @code{"x86_64-linux"}---within @var{body}. In the second case, additionally bind @var{target} to the current cross-compilation target---a GNU triplet such as @code{"arm-linux-gnueabihf"}---or @code{#f} if we are not cross-compiling. @code{let-system} is useful in the occasional case where the object spliced into the gexp depends on the target system, as in this example: @lisp #~(system* #+(let-system system (cond ((string-prefix? "armhf-" system) (file-append qemu "/bin/qemu-system-arm")) ((string-prefix? "x86_64-" system) (file-append qemu "/bin/qemu-system-x86_64")) (else (error "dunno!")))) "-net" "user" #$image) @end lisp @end deffn @deffn {Scheme Syntax} with-parameters ((@var{parameter} @var{value}) @dots{}) @var{exp} This macro is similar to the @code{parameterize} form for dynamically-bound @dfn{parameters} (@pxref{Parameters,,, guile, GNU Guile Reference Manual}). The key difference is that it takes effect when the file-like object returned by @var{exp} is lowered to a derivation or store item. A typical use of @code{with-parameters} is to force the system in effect for a given object: @lisp (with-parameters ((%current-system "i686-linux")) coreutils) @end lisp The example above returns an object that corresponds to the i686 build of Coreutils, regardless of the current value of @code{%current-system}. @end deffn Of course, in addition to gexps embedded in ``host'' code, there are also modules containing build tools. To make it clear that they are meant to be used in the build stratum, these modules are kept in the @code{(guix build @dots{})} name space. @cindex lowering, of high-level objects in gexps Internally, high-level objects are @dfn{lowered}, using their compiler, to either derivations or store items. For instance, lowering a package yields a derivation, and lowering a @code{plain-file} yields a store item. This is achieved using the @code{lower-object} monadic procedure. @deffn {Monadic Procedure} lower-object @var{obj} [@var{system}] @ [#:target #f] Return as a value in @code{%store-monad} the derivation or store item corresponding to @var{obj} for @var{system}, cross-compiling for @var{target} if @var{target} is true. @var{obj} must be an object that has an associated gexp compiler, such as a @code{}. @end deffn @node Invoking guix repl @section Invoking @command{guix repl} @cindex REPL, read-eval-print loop, script The @command{guix repl} command makes it easier to program Guix in Guile by launching a Guile @dfn{read-eval-print loop} (REPL) for interactive programming (@pxref{Using Guile Interactively,,, guile, GNU Guile Reference Manual}), or by running Guile scripts (@pxref{Running Guile Scripts,,, guile, GNU Guile Reference Manual}). Compared to just launching the @command{guile} command, @command{guix repl} guarantees that all the Guix modules and all its dependencies are available in the search path. The general syntax is: @example guix repl @var{options} [@var{file} @var{args}] @end example When a @var{file} argument is provided, @var{file} is executed as a Guile scripts: @example guix repl my-script.scm @end example To pass arguments to the script, use @code{--} to prevent them from being interpreted as arguments to @command{guix repl} itself: @example guix repl -- my-script.scm --input=foo.txt @end example To make a script executable directly from the shell, using the guix executable that is on the user's search path, add the following two lines at the top of the script: @example @code{#!/usr/bin/env -S guix repl --} @code{!#} @end example Without a file name argument, a Guile REPL is started: @example $ guix repl scheme@@(guile-user)> ,use (gnu packages base) scheme@@(guile-user)> coreutils $1 = # @end example @cindex inferiors In addition, @command{guix repl} implements a simple machine-readable REPL protocol for use by @code{(guix inferior)}, a facility to interact with @dfn{inferiors}, separate processes running a potentially different revision of Guix. The available options are as follows: @table @code @item --type=@var{type} @itemx -t @var{type} Start a REPL of the given @var{TYPE}, which can be one of the following: @table @code @item guile This is default, and it spawns a standard full-featured Guile REPL. @item machine Spawn a REPL that uses the machine-readable protocol. This is the protocol that the @code{(guix inferior)} module speaks. @end table @item --listen=@var{endpoint} By default, @command{guix repl} reads from standard input and writes to standard output. When this option is passed, it will instead listen for connections on @var{endpoint}. Here are examples of valid options: @table @code @item --listen=tcp:37146 Accept connections on localhost on port 37146. @item --listen=unix:/tmp/socket Accept connections on the Unix-domain socket @file{/tmp/socket}. @end table @item --load-path=@var{directory} @itemx -L @var{directory} Add @var{directory} to the front of the package module search path (@pxref{Package Modules}). This allows users to define their own packages and make them visible to the script or REPL. @item -q Inhibit loading of the @file{~/.guile} file. By default, that configuration file is loaded when spawning a @code{guile} REPL. @end table @c ********************************************************************* @node Utilities @chapter Utilities This section describes Guix command-line utilities. Some of them are primarily targeted at developers and users who write new package definitions, while others are more generally useful. They complement the Scheme programming interface of Guix in a convenient way. @menu * Invoking guix build:: Building packages from the command line. * Invoking guix edit:: Editing package definitions. * Invoking guix download:: Downloading a file and printing its hash. * Invoking guix hash:: Computing the cryptographic hash of a file. * Invoking guix import:: Importing package definitions. * Invoking guix refresh:: Updating package definitions. * Invoking guix lint:: Finding errors in package definitions. * Invoking guix size:: Profiling disk usage. * Invoking guix graph:: Visualizing the graph of packages. * Invoking guix publish:: Sharing substitutes. * Invoking guix challenge:: Challenging substitute servers. * Invoking guix copy:: Copying to and from a remote store. * Invoking guix container:: Process isolation. * Invoking guix weather:: Assessing substitute availability. * Invoking guix processes:: Listing client processes. @end menu @node Invoking guix build @section Invoking @command{guix build} @cindex package building @cindex @command{guix build} The @command{guix build} command builds packages or derivations and their dependencies, and prints the resulting store paths. Note that it does not modify the user's profile---this is the job of the @command{guix package} command (@pxref{Invoking guix package}). Thus, it is mainly useful for distribution developers. The general syntax is: @example guix build @var{options} @var{package-or-derivation}@dots{} @end example As an example, the following command builds the latest versions of Emacs and of Guile, displays their build logs, and finally displays the resulting directories: @example guix build emacs guile @end example Similarly, the following command builds all the available packages: @example guix build --quiet --keep-going \ `guix package -A | cut -f1,2 --output-delimiter=@@` @end example @var{package-or-derivation} may be either the name of a package found in the software distribution such as @code{coreutils} or @code{coreutils@@8.20}, or a derivation such as @file{/gnu/store/@dots{}-coreutils-8.19.drv}. In the former case, a package with the corresponding name (and optionally version) is searched for among the GNU distribution modules (@pxref{Package Modules}). Alternatively, the @option{--expression} option may be used to specify a Scheme expression that evaluates to a package; this is useful when disambiguating among several same-named packages or package variants is needed. There may be zero or more @var{options}. The available options are described in the subsections below. @menu * Common Build Options:: Build options for most commands. * Package Transformation Options:: Creating variants of packages. * Additional Build Options:: Options specific to 'guix build'. * Debugging Build Failures:: Real life packaging experience. @end menu @node Common Build Options @subsection Common Build Options A number of options that control the build process are common to @command{guix build} and other commands that can spawn builds, such as @command{guix package} or @command{guix archive}. These are the following: @table @code @item --load-path=@var{directory} @itemx -L @var{directory} Add @var{directory} to the front of the package module search path (@pxref{Package Modules}). This allows users to define their own packages and make them visible to the command-line tools. @item --keep-failed @itemx -K Keep the build tree of failed builds. Thus, if a build fails, its build tree is kept under @file{/tmp}, in a directory whose name is shown at the end of the build log. This is useful when debugging build issues. @xref{Debugging Build Failures}, for tips and tricks on how to debug build issues. This option implies @option{--no-offload}, and it has no effect when connecting to a remote daemon with a @code{guix://} URI (@pxref{The Store, the @env{GUIX_DAEMON_SOCKET} variable}). @item --keep-going @itemx -k Keep going when some of the derivations fail to build; return only once all the builds have either completed or failed. The default behavior is to stop as soon as one of the specified derivations has failed. @item --dry-run @itemx -n Do not build the derivations. @anchor{fallback-option} @item --fallback When substituting a pre-built binary fails, fall back to building packages locally (@pxref{Substitution Failure}). @item --substitute-urls=@var{urls} @anchor{client-substitute-urls} Consider @var{urls} the whitespace-separated list of substitute source URLs, overriding the default list of URLs of @command{guix-daemon} (@pxref{daemon-substitute-urls,, @command{guix-daemon} URLs}). This means that substitutes may be downloaded from @var{urls}, provided they are signed by a key authorized by the system administrator (@pxref{Substitutes}). When @var{urls} is the empty string, substitutes are effectively disabled. @item --no-substitutes Do not use substitutes for build products. That is, always build things locally instead of allowing downloads of pre-built binaries (@pxref{Substitutes}). @item --no-grafts Do not ``graft'' packages. In practice, this means that package updates available as grafts are not applied. @xref{Security Updates}, for more information on grafts. @item --rounds=@var{n} Build each derivation @var{n} times in a row, and raise an error if consecutive build results are not bit-for-bit identical. This is a useful way to detect non-deterministic builds processes. Non-deterministic build processes are a problem because they make it practically impossible for users to @emph{verify} whether third-party binaries are genuine. @xref{Invoking guix challenge}, for more. When used in conjunction with @option{--keep-failed}, the differing output is kept in the store, under @file{/gnu/store/@dots{}-check}. This makes it easy to look for differences between the two results. @item --no-offload Do not use offload builds to other machines (@pxref{Daemon Offload Setup}). That is, always build things locally instead of offloading builds to remote machines. @item --max-silent-time=@var{seconds} When the build or substitution process remains silent for more than @var{seconds}, terminate it and report a build failure. By default, the daemon's setting is honored (@pxref{Invoking guix-daemon, @option{--max-silent-time}}). @item --timeout=@var{seconds} Likewise, when the build or substitution process lasts for more than @var{seconds}, terminate it and report a build failure. By default, the daemon's setting is honored (@pxref{Invoking guix-daemon, @option{--timeout}}). @c Note: This option is actually not part of %standard-build-options but @c most programs honor it. @cindex verbosity, of the command-line tools @cindex build logs, verbosity @item -v @var{level} @itemx --verbosity=@var{level} Use the given verbosity @var{level}, an integer. Choosing 0 means that no output is produced, 1 is for quiet output, and 2 shows all the build log output on standard error. @item --cores=@var{n} @itemx -c @var{n} Allow the use of up to @var{n} CPU cores for the build. The special value @code{0} means to use as many CPU cores as available. @item --max-jobs=@var{n} @itemx -M @var{n} Allow at most @var{n} build jobs in parallel. @xref{Invoking guix-daemon, @option{--max-jobs}}, for details about this option and the equivalent @command{guix-daemon} option. @item --debug=@var{level} Produce debugging output coming from the build daemon. @var{level} must be an integer between 0 and 5; higher means more verbose output. Setting a level of 4 or more may be helpful when debugging setup issues with the build daemon. @end table Behind the scenes, @command{guix build} is essentially an interface to the @code{package-derivation} procedure of the @code{(guix packages)} module, and to the @code{build-derivations} procedure of the @code{(guix derivations)} module. In addition to options explicitly passed on the command line, @command{guix build} and other @command{guix} commands that support building honor the @env{GUIX_BUILD_OPTIONS} environment variable. @defvr {Environment Variable} GUIX_BUILD_OPTIONS Users can define this variable to a list of command line options that will automatically be used by @command{guix build} and other @command{guix} commands that can perform builds, as in the example below: @example $ export GUIX_BUILD_OPTIONS="--no-substitutes -c 2 -L /foo/bar" @end example These options are parsed independently, and the result is appended to the parsed command-line options. @end defvr @node Package Transformation Options @subsection Package Transformation Options @cindex package variants Another set of command-line options supported by @command{guix build} and also @command{guix package} are @dfn{package transformation options}. These are options that make it possible to define @dfn{package variants}---for instance, packages built from different source code. This is a convenient way to create customized packages on the fly without having to type in the definitions of package variants (@pxref{Defining Packages}). Package transformation options are preserved across upgrades: @command{guix upgrade} attempts to apply transformation options initially used when creating the profile to the upgraded packages. The available options are listed below. Most commands support them and also support a @option{--help-transform} option that lists all the available options and a synopsis (these options are not shown in the @option{--help} output for brevity). @table @code @item --with-source=@var{source} @itemx --with-source=@var{package}=@var{source} @itemx --with-source=@var{package}@@@var{version}=@var{source} Use @var{source} as the source of @var{package}, and @var{version} as its version number. @var{source} must be a file name or a URL, as for @command{guix download} (@pxref{Invoking guix download}). When @var{package} is omitted, it is taken to be the package name specified on the command line that matches the base of @var{source}---e.g., if @var{source} is @code{/src/guile-2.0.10.tar.gz}, the corresponding package is @code{guile}. Likewise, when @var{version} is omitted, the version string is inferred from @var{source}; in the previous example, it is @code{2.0.10}. This option allows users to try out versions of packages other than the one provided by the distribution. The example below downloads @file{ed-1.7.tar.gz} from a GNU mirror and uses that as the source for the @code{ed} package: @example guix build ed --with-source=mirror://gnu/ed/ed-1.7.tar.gz @end example As a developer, @option{--with-source} makes it easy to test release candidates: @example guix build guile --with-source=../guile-2.0.9.219-e1bb7.tar.xz @end example @dots{} or to build from a checkout in a pristine environment: @example $ git clone git://git.sv.gnu.org/guix.git $ guix build guix --with-source=guix@@1.0=./guix @end example @item --with-input=@var{package}=@var{replacement} Replace dependency on @var{package} by a dependency on @var{replacement}. @var{package} must be a package name, and @var{replacement} must be a package specification such as @code{guile} or @code{guile@@1.8}. For instance, the following command builds Guix, but replaces its dependency on the current stable version of Guile with a dependency on the legacy version of Guile, @code{guile@@2.0}: @example guix build --with-input=guile=guile@@2.0 guix @end example This is a recursive, deep replacement. So in this example, both @code{guix} and its dependency @code{guile-json} (which also depends on @code{guile}) get rebuilt against @code{guile@@2.0}. This is implemented using the @code{package-input-rewriting} Scheme procedure (@pxref{Defining Packages, @code{package-input-rewriting}}). @item --with-graft=@var{package}=@var{replacement} This is similar to @option{--with-input} but with an important difference: instead of rebuilding the whole dependency chain, @var{replacement} is built and then @dfn{grafted} onto the binaries that were initially referring to @var{package}. @xref{Security Updates}, for more information on grafts. For example, the command below grafts version 3.5.4 of GnuTLS onto Wget and all its dependencies, replacing references to the version of GnuTLS they currently refer to: @example guix build --with-graft=gnutls=gnutls@@3.5.4 wget @end example This has the advantage of being much faster than rebuilding everything. But there is a caveat: it works if and only if @var{package} and @var{replacement} are strictly compatible---for example, if they provide a library, the application binary interface (ABI) of those libraries must be compatible. If @var{replacement} is somehow incompatible with @var{package}, then the resulting package may be unusable. Use with care! @cindex debugging info, rebuilding @item --with-debug-info=@var{package} Build @var{package} in a way that preserves its debugging info and graft it onto packages that depend on it. This is useful if @var{package} does not already provide debugging info as a @code{debug} output (@pxref{Installing Debugging Files}). For example, suppose you're experiencing a crash in Inkscape and would like to see what's up in GLib, a library deep down in Inkscape's dependency graph. GLib lacks a @code{debug} output, so debugging is tough. Fortunately, you rebuild GLib with debugging info and tack it on Inkscape: @example guix install inkscape --with-debug-info=glib @end example Only GLib needs to be recompiled so this takes a reasonable amount of time. @xref{Installing Debugging Files}, for more info. @quotation Note Under the hood, this option works by passing the @samp{#:strip-binaries? #f} to the build system of the package of interest (@pxref{Build Systems}). Most build systems support that option but some do not. In that case, an error is raised. Likewise, if a C/C++ package is built without @code{-g} (which is rarely the case), debugging info will remain unavailable even when @code{#:strip-binaries?} is false. @end quotation @cindex tool chain, changing the build tool chain of a package @item --with-c-toolchain=@var{package}=@var{toolchain} This option changes the compilation of @var{package} and everything that depends on it so that they get built with @var{toolchain} instead of the default GNU tool chain for C/C++. Consider this example: @example guix build octave-cli \ --with-c-toolchain=fftw=gcc-toolchain@@10 \ --with-c-toolchain=fftwf=gcc-toolchain@@10 @end example The command above builds a variant of the @code{fftw} and @code{fftwf} packages using version 10 of @code{gcc-toolchain} instead of the default tool chain, and then builds a variant of the GNU@tie{}Octave command-line interface using them. GNU@tie{}Octave itself is also built with @code{gcc-toolchain@@10}. This other example builds the Hardware Locality (@code{hwloc}) library and its dependents up to @code{intel-mpi-benchmarks} with the Clang C compiler: @example guix build --with-c-toolchain=hwloc=clang-toolchain \ intel-mpi-benchmarks @end example @quotation Note There can be application binary interface (ABI) incompatibilities among tool chains. This is particularly true of the C++ standard library and run-time support libraries such as that of OpenMP. By rebuilding all dependents with the same tool chain, @option{--with-c-toolchain} minimizes the risks of incompatibility but cannot entirely eliminate them. Choose @var{package} wisely. @end quotation @item --with-git-url=@var{package}=@var{url} @cindex Git, using the latest commit @cindex latest commit, building Build @var{package} from the latest commit of the @code{master} branch of the Git repository at @var{url}. Git sub-modules of the repository are fetched, recursively. For example, the following command builds the NumPy Python library against the latest commit of the master branch of Python itself: @example guix build python-numpy \ --with-git-url=python=https://github.com/python/cpython @end example This option can also be combined with @option{--with-branch} or @option{--with-commit} (see below). @cindex continuous integration Obviously, since it uses the latest commit of the given branch, the result of such a command varies over time. Nevertheless it is a convenient way to rebuild entire software stacks against the latest commit of one or more packages. This is particularly useful in the context of continuous integration (CI). Checkouts are kept in a cache under @file{~/.cache/guix/checkouts} to speed up consecutive accesses to the same repository. You may want to clean it up once in a while to save disk space. @item --with-branch=@var{package}=@var{branch} Build @var{package} from the latest commit of @var{branch}. If the @code{source} field of @var{package} is an origin with the @code{git-fetch} method (@pxref{origin Reference}) or a @code{git-checkout} object, the repository URL is taken from that @code{source}. Otherwise you have to use @option{--with-git-url} to specify the URL of the Git repository. For instance, the following command builds @code{guile-sqlite3} from the latest commit of its @code{master} branch, and then builds @code{guix} (which depends on it) and @code{cuirass} (which depends on @code{guix}) against this specific @code{guile-sqlite3} build: @example guix build --with-branch=guile-sqlite3=master cuirass @end example @item --with-commit=@var{package}=@var{commit} This is similar to @option{--with-branch}, except that it builds from @var{commit} rather than the tip of a branch. @var{commit} must be a valid Git commit SHA1 identifier or a tag. @item --with-patch=@var{package}=@var{file} Add @var{file} to the list of patches applied to @var{package}, where @var{package} is a spec such as @code{python@@3.8} or @code{glibc}. @var{file} must contain a patch; it is applied with the flags specified in the @code{origin} of @var{package} (@pxref{origin Reference}), which by default includes @code{-p1} (@pxref{patch Directories,,, diffutils, Comparing and Merging Files}). As an example, the command below rebuilds Coreutils with the GNU C Library (glibc) patched with the given patch: @example guix build coreutils --with-patch=glibc=./glibc-frob.patch @end example In this example, glibc itself as well as everything that leads to Coreutils in the dependency graph is rebuilt. @cindex test suite, skipping @item --without-tests=@var{package} Build @var{package} without running its tests. This can be useful in situations where you want to skip the lengthy test suite of a intermediate package, or if a package's test suite fails in a non-deterministic fashion. It should be used with care because running the test suite is a good way to ensure a package is working as intended. Turning off tests leads to a different store item. Consequently, when using this option, anything that depends on @var{package} must be rebuilt, as in this example: @example guix install --without-tests=python python-notebook @end example The command above installs @code{python-notebook} on top of @code{python} built without running its test suite. To do so, it also rebuilds everything that depends on @code{python}, including @code{python-notebook} itself. Internally, @option{--without-tests} relies on changing the @code{#:tests?} option of a package's @code{check} phase (@pxref{Build Systems}). Note that some packages use a customized @code{check} phase that does not respect a @code{#:tests? #f} setting. Therefore, @option{--without-tests} has no effect on these packages. @end table Wondering how to achieve the same effect using Scheme code, for example in your manifest, or how to write your own package transformation? @xref{Defining Package Variants}, for an overview of the programming interfaces available. @node Additional Build Options @subsection Additional Build Options The command-line options presented below are specific to @command{guix build}. @table @code @item --quiet @itemx -q Build quietly, without displaying the build log; this is equivalent to @option{--verbosity=0}. Upon completion, the build log is kept in @file{/var} (or similar) and can always be retrieved using the @option{--log-file} option. @item --file=@var{file} @itemx -f @var{file} Build the package, derivation, or other file-like object that the code within @var{file} evaluates to (@pxref{G-Expressions, file-like objects}). As an example, @var{file} might contain a package definition like this (@pxref{Defining Packages}): @lisp @include package-hello.scm @end lisp The @var{file} may also contain a JSON representation of one or more package definitions. Running @code{guix build -f} on @file{hello.json} with the following contents would result in building the packages @code{myhello} and @code{greeter}: @example @verbatiminclude package-hello.json @end example @item --manifest=@var{manifest} @itemx -m @var{manifest} Build all packages listed in the given @var{manifest} (@pxref{profile-manifest, @option{--manifest}}). @item --expression=@var{expr} @itemx -e @var{expr} Build the package or derivation @var{expr} evaluates to. For example, @var{expr} may be @code{(@@ (gnu packages guile) guile-1.8)}, which unambiguously designates this specific variant of version 1.8 of Guile. Alternatively, @var{expr} may be a G-expression, in which case it is used as a build program passed to @code{gexp->derivation} (@pxref{G-Expressions}). Lastly, @var{expr} may refer to a zero-argument monadic procedure (@pxref{The Store Monad}). The procedure must return a derivation as a monadic value, which is then passed through @code{run-with-store}. @item --source @itemx -S Build the source derivations of the packages, rather than the packages themselves. For instance, @code{guix build -S gcc} returns something like @file{/gnu/store/@dots{}-gcc-4.7.2.tar.bz2}, which is the GCC source tarball. The returned source tarball is the result of applying any patches and code snippets specified in the package @code{origin} (@pxref{Defining Packages}). @cindex source, verification As with other derivations, the result of building a source derivation can be verified using the @option{--check} option (@pxref{build-check}). This is useful to validate that a (potentially already built or substituted, thus cached) package source matches against its declared hash. Note that @command{guix build -S} compiles the sources only of the specified packages. They do not include the sources of statically linked dependencies and by themselves are insufficient for reproducing the packages. @item --sources Fetch and return the source of @var{package-or-derivation} and all their dependencies, recursively. This is a handy way to obtain a local copy of all the source code needed to build @var{packages}, allowing you to eventually build them even without network access. It is an extension of the @option{--source} option and can accept one of the following optional argument values: @table @code @item package This value causes the @option{--sources} option to behave in the same way as the @option{--source} option. @item all Build the source derivations of all packages, including any source that might be listed as @code{inputs}. This is the default value. @example $ guix build --sources tzdata The following derivations will be built: /gnu/store/@dots{}-tzdata2015b.tar.gz.drv /gnu/store/@dots{}-tzcode2015b.tar.gz.drv @end example @item transitive Build the source derivations of all packages, as well of all transitive inputs to the packages. This can be used e.g.@: to prefetch package source for later offline building. @example $ guix build --sources=transitive tzdata The following derivations will be built: /gnu/store/@dots{}-tzcode2015b.tar.gz.drv /gnu/store/@dots{}-findutils-4.4.2.tar.xz.drv /gnu/store/@dots{}-grep-2.21.tar.xz.drv /gnu/store/@dots{}-coreutils-8.23.tar.xz.drv /gnu/store/@dots{}-make-4.1.tar.xz.drv /gnu/store/@dots{}-bash-4.3.tar.xz.drv @dots{} @end example @end table @item --system=@var{system} @itemx -s @var{system} Attempt to build for @var{system}---e.g., @code{i686-linux}---instead of the system type of the build host. The @command{guix build} command allows you to repeat this option several times, in which case it builds for all the specified systems; other commands ignore extraneous @option{-s} options. @quotation Note The @option{--system} flag is for @emph{native} compilation and must not be confused with cross-compilation. See @option{--target} below for information on cross-compilation. @end quotation An example use of this is on Linux-based systems, which can emulate different personalities. For instance, passing @option{--system=i686-linux} on an @code{x86_64-linux} system or @option{--system=armhf-linux} on an @code{aarch64-linux} system allows you to build packages in a complete 32-bit environment. @quotation Note Building for an @code{armhf-linux} system is unconditionally enabled on @code{aarch64-linux} machines, although certain aarch64 chipsets do not allow for this functionality, notably the ThunderX. @end quotation Similarly, when transparent emulation with QEMU and @code{binfmt_misc} is enabled (@pxref{Virtualization Services, @code{qemu-binfmt-service-type}}), you can build for any system for which a QEMU @code{binfmt_misc} handler is installed. Builds for a system other than that of the machine you are using can also be offloaded to a remote machine of the right architecture. @xref{Daemon Offload Setup}, for more information on offloading. @item --target=@var{triplet} @cindex cross-compilation Cross-build for @var{triplet}, which must be a valid GNU triplet, such as @code{"aarch64-linux-gnu"} (@pxref{Specifying Target Triplets, GNU configuration triplets,, autoconf, Autoconf}). @anchor{build-check} @item --check @cindex determinism, checking @cindex reproducibility, checking Rebuild @var{package-or-derivation}, which are already available in the store, and raise an error if the build results are not bit-for-bit identical. This mechanism allows you to check whether previously installed substitutes are genuine (@pxref{Substitutes}), or whether the build result of a package is deterministic. @xref{Invoking guix challenge}, for more background information and tools. When used in conjunction with @option{--keep-failed}, the differing output is kept in the store, under @file{/gnu/store/@dots{}-check}. This makes it easy to look for differences between the two results. @item --repair @cindex repairing store items @cindex corruption, recovering from Attempt to repair the specified store items, if they are corrupt, by re-downloading or rebuilding them. This operation is not atomic and thus restricted to @code{root}. @item --derivations @itemx -d Return the derivation paths, not the output paths, of the given packages. @item --root=@var{file} @itemx -r @var{file} @cindex GC roots, adding @cindex garbage collector roots, adding Make @var{file} a symlink to the result, and register it as a garbage collector root. Consequently, the results of this @command{guix build} invocation are protected from garbage collection until @var{file} is removed. When that option is omitted, build results are eligible for garbage collection as soon as the build completes. @xref{Invoking guix gc}, for more on GC roots. @item --log-file @cindex build logs, access Return the build log file names or URLs for the given @var{package-or-derivation}, or raise an error if build logs are missing. This works regardless of how packages or derivations are specified. For instance, the following invocations are equivalent: @example guix build --log-file `guix build -d guile` guix build --log-file `guix build guile` guix build --log-file guile guix build --log-file -e '(@@ (gnu packages guile) guile-2.0)' @end example If a log is unavailable locally, and unless @option{--no-substitutes} is passed, the command looks for a corresponding log on one of the substitute servers (as specified with @option{--substitute-urls}). So for instance, imagine you want to see the build log of GDB on MIPS, but you are actually on an @code{x86_64} machine: @example $ guix build --log-file gdb -s aarch64-linux https://@value{SUBSTITUTE-SERVER}/log/@dots{}-gdb-7.10 @end example You can freely access a huge library of build logs! @end table @node Debugging Build Failures @subsection Debugging Build Failures @cindex build failures, debugging When defining a new package (@pxref{Defining Packages}), you will probably find yourself spending some time debugging and tweaking the build until it succeeds. To do that, you need to operate the build commands yourself in an environment as close as possible to the one the build daemon uses. To that end, the first thing to do is to use the @option{--keep-failed} or @option{-K} option of @command{guix build}, which will keep the failed build tree in @file{/tmp} or whatever directory you specified as @env{TMPDIR} (@pxref{Invoking guix build, @option{--keep-failed}}). From there on, you can @command{cd} to the failed build tree and source the @file{environment-variables} file, which contains all the environment variable definitions that were in place when the build failed. So let's say you're debugging a build failure in package @code{foo}; a typical session would look like this: @example $ guix build foo -K @dots{} @i{build fails} $ cd /tmp/guix-build-foo.drv-0 $ source ./environment-variables $ cd foo-1.2 @end example Now, you can invoke commands as if you were the daemon (almost) and troubleshoot your build process. Sometimes it happens that, for example, a package's tests pass when you run them manually but they fail when the daemon runs them. This can happen because the daemon runs builds in containers where, unlike in our environment above, network access is missing, @file{/bin/sh} does not exist, etc. (@pxref{Build Environment Setup}). In such cases, you may need to run inspect the build process from within a container similar to the one the build daemon creates: @example $ guix build -K foo @dots{} $ cd /tmp/guix-build-foo.drv-0 $ guix environment --no-grafts -C foo --ad-hoc strace gdb [env]# source ./environment-variables [env]# cd foo-1.2 @end example Here, @command{guix environment -C} creates a container and spawns a new shell in it (@pxref{Invoking guix environment}). The @command{--ad-hoc strace gdb} part adds the @command{strace} and @command{gdb} commands to the container, which you may find handy while debugging. The @option{--no-grafts} option makes sure we get the exact same environment, with ungrafted packages (@pxref{Security Updates}, for more info on grafts). To get closer to a container like that used by the build daemon, we can remove @file{/bin/sh}: @example [env]# rm /bin/sh @end example (Don't worry, this is harmless: this is all happening in the throw-away container created by @command{guix environment}.) The @command{strace} command is probably not in the search path, but we can run: @example [env]# $GUIX_ENVIRONMENT/bin/strace -f -o log make check @end example In this way, not only you will have reproduced the environment variables the daemon uses, you will also be running the build process in a container similar to the one the daemon uses. @node Invoking guix edit @section Invoking @command{guix edit} @cindex @command{guix edit} @cindex package definition, editing So many packages, so many source files! The @command{guix edit} command facilitates the life of users and packagers by pointing their editor at the source file containing the definition of the specified packages. For instance: @example guix edit gcc@@4.9 vim @end example @noindent launches the program specified in the @env{VISUAL} or in the @env{EDITOR} environment variable to view the recipe of GCC@tie{}4.9.3 and that of Vim. If you are using a Guix Git checkout (@pxref{Building from Git}), or have created your own packages on @env{GUIX_PACKAGE_PATH} (@pxref{Package Modules}), you will be able to edit the package recipes. In other cases, you will be able to examine the read-only recipes for packages currently in the store. Instead of @env{GUIX_PACKAGE_PATH}, the command-line option @option{--load-path=@var{directory}} (or in short @option{-L @var{directory}}) allows you to add @var{directory} to the front of the package module search path and so make your own packages visible. @node Invoking guix download @section Invoking @command{guix download} @cindex @command{guix download} @cindex downloading package sources When writing a package definition, developers typically need to download a source tarball, compute its SHA256 hash, and write that hash in the package definition (@pxref{Defining Packages}). The @command{guix download} tool helps with this task: it downloads a file from the given URI, adds it to the store, and prints both its file name in the store and its SHA256 hash. The fact that the downloaded file is added to the store saves bandwidth: when the developer eventually tries to build the newly defined package with @command{guix build}, the source tarball will not have to be downloaded again because it is already in the store. It is also a convenient way to temporarily stash files, which may be deleted eventually (@pxref{Invoking guix gc}). The @command{guix download} command supports the same URIs as used in package definitions. In particular, it supports @code{mirror://} URIs. @code{https} URIs (HTTP over TLS) are supported @emph{provided} the Guile bindings for GnuTLS are available in the user's environment; when they are not available, an error is raised. @xref{Guile Preparations, how to install the GnuTLS bindings for Guile,, gnutls-guile, GnuTLS-Guile}, for more information. @command{guix download} verifies HTTPS server certificates by loading the certificates of X.509 authorities from the directory pointed to by the @env{SSL_CERT_DIR} environment variable (@pxref{X.509 Certificates}), unless @option{--no-check-certificate} is used. The following options are available: @table @code @item --hash=@var{algorithm} @itemx -H @var{algorithm} Compute a hash using the specified @var{algorithm}. @xref{Invoking guix hash}, for more information. @item --format=@var{fmt} @itemx -f @var{fmt} Write the hash in the format specified by @var{fmt}. For more information on the valid values for @var{fmt}, @pxref{Invoking guix hash}. @item --no-check-certificate Do not validate the X.509 certificates of HTTPS servers. When using this option, you have @emph{absolutely no guarantee} that you are communicating with the authentic server responsible for the given URL, which makes you vulnerable to ``man-in-the-middle'' attacks. @item --output=@var{file} @itemx -o @var{file} Save the downloaded file to @var{file} instead of adding it to the store. @end table @node Invoking guix hash @section Invoking @command{guix hash} @cindex @command{guix hash} The @command{guix hash} command computes the hash of a file. It is primarily a convenience tool for anyone contributing to the distribution: it computes the cryptographic hash of a file, which can be used in the definition of a package (@pxref{Defining Packages}). The general syntax is: @example guix hash @var{option} @var{file} @end example When @var{file} is @code{-} (a hyphen), @command{guix hash} computes the hash of data read from standard input. @command{guix hash} has the following options: @table @code @item --hash=@var{algorithm} @itemx -H @var{algorithm} Compute a hash using the specified @var{algorithm}, @code{sha256} by default. @var{algorithm} must the name of a cryptographic hash algorithm supported by Libgcrypt @i{via} Guile-Gcrypt---e.g., @code{sha512} or @code{sha3-256} (@pxref{Hash Functions,,, guile-gcrypt, Guile-Gcrypt Reference Manual}). @item --format=@var{fmt} @itemx -f @var{fmt} Write the hash in the format specified by @var{fmt}. Supported formats: @code{base64}, @code{nix-base32}, @code{base32}, @code{base16} (@code{hex} and @code{hexadecimal} can be used as well). If the @option{--format} option is not specified, @command{guix hash} will output the hash in @code{nix-base32}. This representation is used in the definitions of packages. @item --recursive @itemx -r Compute the hash on @var{file} recursively. In this case, the hash is computed on an archive containing @var{file}, including its children if it is a directory. Some of the metadata of @var{file} is part of the archive; for instance, when @var{file} is a regular file, the hash is different depending on whether @var{file} is executable or not. Metadata such as time stamps has no impact on the hash (@pxref{Invoking guix archive}). @c FIXME: Replace xref above with xref to an ``Archive'' section when @c it exists. @item --exclude-vcs @itemx -x When combined with @option{--recursive}, exclude version control system directories (@file{.bzr}, @file{.git}, @file{.hg}, etc.). @vindex git-fetch As an example, here is how you would compute the hash of a Git checkout, which is useful when using the @code{git-fetch} method (@pxref{origin Reference}): @example $ git clone http://example.org/foo.git $ cd foo $ guix hash -rx . @end example @end table @node Invoking guix import @section Invoking @command{guix import} @cindex importing packages @cindex package import @cindex package conversion @cindex Invoking @command{guix import} The @command{guix import} command is useful for people who would like to add a package to the distribution with as little work as possible---a legitimate demand. The command knows of a few repositories from which it can ``import'' package metadata. The result is a package definition, or a template thereof, in the format we know (@pxref{Defining Packages}). The general syntax is: @example guix import @var{importer} @var{options}@dots{} @end example @var{importer} specifies the source from which to import package metadata, and @var{options} specifies a package identifier and other options specific to @var{importer}. Some of the importers rely on the ability to run the @command{gpgv} command. For these, GnuPG must be installed and in @code{$PATH}; run @code{guix install gnupg} if needed. Currently, the available ``importers'' are: @table @code @item gnu Import metadata for the given GNU package. This provides a template for the latest version of that GNU package, including the hash of its source tarball, and its canonical synopsis and description. Additional information such as the package dependencies and its license needs to be figured out manually. For example, the following command returns a package definition for GNU@tie{}Hello: @example guix import gnu hello @end example Specific command-line options are: @table @code @item --key-download=@var{policy} As for @command{guix refresh}, specify the policy to handle missing OpenPGP keys when verifying the package signature. @xref{Invoking guix refresh, @option{--key-download}}. @end table @item pypi @cindex pypi Import metadata from the @uref{https://pypi.python.org/, Python Package Index}. Information is taken from the JSON-formatted description available at @code{pypi.python.org} and usually includes all the relevant information, including package dependencies. For maximum efficiency, it is recommended to install the @command{unzip} utility, so that the importer can unzip Python wheels and gather data from them. The command below imports metadata for the @code{itsdangerous} Python package: @example guix import pypi itsdangerous @end example @table @code @item --recursive @itemx -r Traverse the dependency graph of the given upstream package recursively and generate package expressions for all those packages that are not yet in Guix. @end table @item gem @cindex gem Import metadata from @uref{https://rubygems.org/, RubyGems}. Information is taken from the JSON-formatted description available at @code{rubygems.org} and includes most relevant information, including runtime dependencies. There are some caveats, however. The metadata doesn't distinguish between synopses and descriptions, so the same string is used for both fields. Additionally, the details of non-Ruby dependencies required to build native extensions is unavailable and left as an exercise to the packager. The command below imports metadata for the @code{rails} Ruby package: @example guix import gem rails @end example @table @code @item --recursive @itemx -r Traverse the dependency graph of the given upstream package recursively and generate package expressions for all those packages that are not yet in Guix. @end table @item cpan @cindex CPAN Import metadata from @uref{https://www.metacpan.org/, MetaCPAN}. Information is taken from the JSON-formatted metadata provided through @uref{https://fastapi.metacpan.org/, MetaCPAN's API} and includes most relevant information, such as module dependencies. License information should be checked closely. If Perl is available in the store, then the @code{corelist} utility will be used to filter core modules out of the list of dependencies. The command command below imports metadata for the Acme::Boolean Perl module: @example guix import cpan Acme::Boolean @end example @item cran @cindex CRAN @cindex Bioconductor Import metadata from @uref{https://cran.r-project.org/, CRAN}, the central repository for the @uref{https://r-project.org, GNU@tie{}R statistical and graphical environment}. Information is extracted from the @file{DESCRIPTION} file of the package. The command command below imports metadata for the Cairo R package: @example guix import cran Cairo @end example When @option{--recursive} is added, the importer will traverse the dependency graph of the given upstream package recursively and generate package expressions for all those packages that are not yet in Guix. When @option{--style=specification} is added, the importer will generate package definitions whose inputs are package specifications instead of references to package variables. This is useful when generated package definitions are to be appended to existing user modules, as the list of used package modules need not be changed. The default is @option{--style=variable}. When @option{--archive=bioconductor} is added, metadata is imported from @uref{https://www.bioconductor.org/, Bioconductor}, a repository of R packages for the analysis and comprehension of high-throughput genomic data in bioinformatics. Information is extracted from the @file{DESCRIPTION} file contained in the package archive. The command below imports metadata for the GenomicRanges R package: @example guix import cran --archive=bioconductor GenomicRanges @end example Finally, you can also import R packages that have not yet been published on CRAN or Bioconductor as long as they are in a git repository. Use @option{--archive=git} followed by the URL of the git repository: @example guix import cran --archive=git https://github.com/immunogenomics/harmony @end example @item texlive @cindex TeX Live @cindex CTAN Import metadata from @uref{https://www.ctan.org/, CTAN}, the comprehensive TeX archive network for TeX packages that are part of the @uref{https://www.tug.org/texlive/, TeX Live distribution}. Information about the package is obtained through the XML API provided by CTAN, while the source code is downloaded from the SVN repository of the Tex Live project. This is done because the CTAN does not keep versioned archives. The command command below imports metadata for the @code{fontspec} TeX package: @example guix import texlive fontspec @end example When @option{--archive=@var{directory}} is added, the source code is downloaded not from the @file{latex} sub-directory of the @file{texmf-dist/source} tree in the TeX Live SVN repository, but from the specified sibling @var{directory} under the same root. The command below imports metadata for the @code{ifxetex} package from CTAN while fetching the sources from the directory @file{texmf/source/generic}: @example guix import texlive --archive=generic ifxetex @end example @item json @cindex JSON, import Import package metadata from a local JSON file. Consider the following example package definition in JSON format: @example @{ "name": "hello", "version": "2.10", "source": "mirror://gnu/hello/hello-2.10.tar.gz", "build-system": "gnu", "home-page": "https://www.gnu.org/software/hello/", "synopsis": "Hello, GNU world: An example GNU package", "description": "GNU Hello prints a greeting.", "license": "GPL-3.0+", "native-inputs": ["gettext"] @} @end example The field names are the same as for the @code{} record (@xref{Defining Packages}). References to other packages are provided as JSON lists of quoted package specification strings such as @code{guile} or @code{guile@@2.0}. The importer also supports a more explicit source definition using the common fields for @code{} records: @example @{ @dots{} "source": @{ "method": "url-fetch", "uri": "mirror://gnu/hello/hello-2.10.tar.gz", "sha256": @{ "base32": "0ssi1wpaf7plaswqqjwigppsg5fyh99vdlb9kzl7c9lng89ndq1i" @} @} @dots{} @} @end example The command below reads metadata from the JSON file @code{hello.json} and outputs a package expression: @example guix import json hello.json @end example @item nix Import metadata from a local copy of the source of the @uref{https://nixos.org/nixpkgs/, Nixpkgs distribution}@footnote{This relies on the @command{nix-instantiate} command of @uref{https://nixos.org/nix/, Nix}.}. Package definitions in Nixpkgs are typically written in a mixture of Nix-language and Bash code. This command only imports the high-level package structure that is written in the Nix language. It normally includes all the basic fields of a package definition. When importing a GNU package, the synopsis and descriptions are replaced by their canonical upstream variant. Usually, you will first need to do: @example export NIX_REMOTE=daemon @end example @noindent so that @command{nix-instantiate} does not try to open the Nix database. As an example, the command below imports the package definition of LibreOffice (more precisely, it imports the definition of the package bound to the @code{libreoffice} top-level attribute): @example guix import nix ~/path/to/nixpkgs libreoffice @end example @item hackage @cindex hackage Import metadata from the Haskell community's central package archive @uref{https://hackage.haskell.org/, Hackage}. Information is taken from Cabal files and includes all the relevant information, including package dependencies. Specific command-line options are: @table @code @item --stdin @itemx -s Read a Cabal file from standard input. @item --no-test-dependencies @itemx -t Do not include dependencies required only by the test suites. @item --cabal-environment=@var{alist} @itemx -e @var{alist} @var{alist} is a Scheme alist defining the environment in which the Cabal conditionals are evaluated. The accepted keys are: @code{os}, @code{arch}, @code{impl} and a string representing the name of a flag. The value associated with a flag has to be either the symbol @code{true} or @code{false}. The value associated with other keys has to conform to the Cabal file format definition. The default value associated with the keys @code{os}, @code{arch} and @code{impl} is @samp{linux}, @samp{x86_64} and @samp{ghc}, respectively. @item --recursive @itemx -r Traverse the dependency graph of the given upstream package recursively and generate package expressions for all those packages that are not yet in Guix. @end table The command below imports metadata for the latest version of the HTTP Haskell package without including test dependencies and specifying the value of the flag @samp{network-uri} as @code{false}: @example guix import hackage -t -e "'((\"network-uri\" . false))" HTTP @end example A specific package version may optionally be specified by following the package name by an at-sign and a version number as in the following example: @example guix import hackage mtl@@2.1.3.1 @end example @item stackage @cindex stackage The @code{stackage} importer is a wrapper around the @code{hackage} one. It takes a package name, looks up the package version included in a long-term support (LTS) @uref{https://www.stackage.org, Stackage} release and uses the @code{hackage} importer to retrieve its metadata. Note that it is up to you to select an LTS release compatible with the GHC compiler used by Guix. Specific command-line options are: @table @code @item --no-test-dependencies @itemx -t Do not include dependencies required only by the test suites. @item --lts-version=@var{version} @itemx -l @var{version} @var{version} is the desired LTS release version. If omitted the latest release is used. @item --recursive @itemx -r Traverse the dependency graph of the given upstream package recursively and generate package expressions for all those packages that are not yet in Guix. @end table The command below imports metadata for the HTTP Haskell package included in the LTS Stackage release version 7.18: @example guix import stackage --lts-version=7.18 HTTP @end example @item elpa @cindex elpa Import metadata from an Emacs Lisp Package Archive (ELPA) package repository (@pxref{Packages,,, emacs, The GNU Emacs Manual}). Specific command-line options are: @table @code @item --archive=@var{repo} @itemx -a @var{repo} @var{repo} identifies the archive repository from which to retrieve the information. Currently the supported repositories and their identifiers are: @itemize - @item @uref{https://elpa.gnu.org/packages, GNU}, selected by the @code{gnu} identifier. This is the default. Packages from @code{elpa.gnu.org} are signed with one of the keys contained in the GnuPG keyring at @file{share/emacs/25.1/etc/package-keyring.gpg} (or similar) in the @code{emacs} package (@pxref{Package Installation, ELPA package signatures,, emacs, The GNU Emacs Manual}). @item @uref{https://stable.melpa.org/packages, MELPA-Stable}, selected by the @code{melpa-stable} identifier. @item @uref{https://melpa.org/packages, MELPA}, selected by the @code{melpa} identifier. @end itemize @item --recursive @itemx -r Traverse the dependency graph of the given upstream package recursively and generate package expressions for all those packages that are not yet in Guix. @end table @item crate @cindex crate Import metadata from the crates.io Rust package repository @uref{https://crates.io, crates.io}, as in this example: @example guix import crate blake2-rfc @end example The crate importer also allows you to specify a version string: @example guix import crate constant-time-eq@@0.1.0 @end example Additional options include: @table @code @item --recursive @itemx -r Traverse the dependency graph of the given upstream package recursively and generate package expressions for all those packages that are not yet in Guix. @end table @item opam @cindex OPAM @cindex OCaml Import metadata from the @uref{https://opam.ocaml.org/, OPAM} package repository used by the OCaml community. Additional options include: @table @code @item --recursive @itemx -r Traverse the dependency graph of the given upstream package recursively and generate package expressions for all those packages that are not yet in Guix. @item --repo Select the given repository (a repository name). Possible values include: @itemize @item @code{opam}, the default opam repository, @item @code{coq} or @code{coq-released}, the stable repository for coq packages, @item @code{coq-core-dev}, the repository that contains development versions of coq, @item @code{coq-extra-dev}, the repository that contains development versions of coq packages. @end itemize @end table @end table The structure of the @command{guix import} code is modular. It would be useful to have more importers for other package formats, and your help is welcome here (@pxref{Contributing}). @node Invoking guix refresh @section Invoking @command{guix refresh} @cindex @command {guix refresh} The primary audience of the @command{guix refresh} command is developers of the GNU software distribution. By default, it reports any packages provided by the distribution that are outdated compared to the latest upstream version, like this: @example $ guix refresh gnu/packages/gettext.scm:29:13: gettext would be upgraded from 0.18.1.1 to 0.18.2.1 gnu/packages/glib.scm:77:12: glib would be upgraded from 2.34.3 to 2.37.0 @end example Alternatively, one can specify packages to consider, in which case a warning is emitted for packages that lack an updater: @example $ guix refresh coreutils guile guile-ssh gnu/packages/ssh.scm:205:2: warning: no updater for guile-ssh gnu/packages/guile.scm:136:12: guile would be upgraded from 2.0.12 to 2.0.13 @end example @command{guix refresh} browses the upstream repository of each package and determines the highest version number of the releases therein. The command knows how to update specific types of packages: GNU packages, ELPA packages, etc.---see the documentation for @option{--type} below. There are many packages, though, for which it lacks a method to determine whether a new upstream release is available. However, the mechanism is extensible, so feel free to get in touch with us to add a new method! @table @code @item --recursive Consider the packages specified, and all the packages upon which they depend. @example $ guix refresh --recursive coreutils gnu/packages/acl.scm:35:2: warning: no updater for acl gnu/packages/m4.scm:30:12: info: 1.4.18 is already the latest version of m4 gnu/packages/xml.scm:68:2: warning: no updater for expat gnu/packages/multiprecision.scm:40:12: info: 6.1.2 is already the latest version of gmp @dots{} @end example @end table Sometimes the upstream name differs from the package name used in Guix, and @command{guix refresh} needs a little help. Most updaters honor the @code{upstream-name} property in package definitions, which can be used to that effect: @lisp (define-public network-manager (package (name "network-manager") ;; @dots{} (properties '((upstream-name . "NetworkManager"))))) @end lisp When passed @option{--update}, it modifies distribution source files to update the version numbers and source tarball hashes of those package recipes (@pxref{Defining Packages}). This is achieved by downloading each package's latest source tarball and its associated OpenPGP signature, authenticating the downloaded tarball against its signature using @command{gpgv}, and finally computing its hash---note that GnuPG must be installed and in @code{$PATH}; run @code{guix install gnupg} if needed. When the public key used to sign the tarball is missing from the user's keyring, an attempt is made to automatically retrieve it from a public key server; when this is successful, the key is added to the user's keyring; otherwise, @command{guix refresh} reports an error. The following options are supported: @table @code @item --expression=@var{expr} @itemx -e @var{expr} Consider the package @var{expr} evaluates to. This is useful to precisely refer to a package, as in this example: @example guix refresh -l -e '(@@@@ (gnu packages commencement) glibc-final)' @end example This command lists the dependents of the ``final'' libc (essentially all the packages). @item --update @itemx -u Update distribution source files (package recipes) in place. This is usually run from a checkout of the Guix source tree (@pxref{Running Guix Before It Is Installed}): @example $ ./pre-inst-env guix refresh -s non-core -u @end example @xref{Defining Packages}, for more information on package definitions. @item --select=[@var{subset}] @itemx -s @var{subset} Select all the packages in @var{subset}, one of @code{core} or @code{non-core}. The @code{core} subset refers to all the packages at the core of the distribution---i.e., packages that are used to build ``everything else''. This includes GCC, libc, Binutils, Bash, etc. Usually, changing one of these packages in the distribution entails a rebuild of all the others. Thus, such updates are an inconvenience to users in terms of build time or bandwidth used to achieve the upgrade. The @code{non-core} subset refers to the remaining packages. It is typically useful in cases where an update of the core packages would be inconvenient. @item --manifest=@var{file} @itemx -m @var{file} Select all the packages from the manifest in @var{file}. This is useful to check if any packages of the user manifest can be updated. @item --type=@var{updater} @itemx -t @var{updater} Select only packages handled by @var{updater} (may be a comma-separated list of updaters). Currently, @var{updater} may be one of: @table @code @item gnu the updater for GNU packages; @item savannah the updater for packages hosted at @uref{https://savannah.gnu.org, Savannah}; @item gnome the updater for GNOME packages; @item kde the updater for KDE packages; @item xorg the updater for X.org packages; @item kernel.org the updater for packages hosted on kernel.org; @item elpa the updater for @uref{https://elpa.gnu.org/, ELPA} packages; @item cran the updater for @uref{https://cran.r-project.org/, CRAN} packages; @item bioconductor the updater for @uref{https://www.bioconductor.org/, Bioconductor} R packages; @item cpan the updater for @uref{https://www.cpan.org/, CPAN} packages; @item pypi the updater for @uref{https://pypi.python.org, PyPI} packages. @item gem the updater for @uref{https://rubygems.org, RubyGems} packages. @item github the updater for @uref{https://github.com, GitHub} packages. @item hackage the updater for @uref{https://hackage.haskell.org, Hackage} packages. @item stackage the updater for @uref{https://www.stackage.org, Stackage} packages. @item crate the updater for @uref{https://crates.io, Crates} packages. @item launchpad the updater for @uref{https://launchpad.net, Launchpad} packages. @end table For instance, the following command only checks for updates of Emacs packages hosted at @code{elpa.gnu.org} and for updates of CRAN packages: @example $ guix refresh --type=elpa,cran gnu/packages/statistics.scm:819:13: r-testthat would be upgraded from 0.10.0 to 0.11.0 gnu/packages/emacs.scm:856:13: emacs-auctex would be upgraded from 11.88.6 to 11.88.9 @end example @end table In addition, @command{guix refresh} can be passed one or more package names, as in this example: @example $ ./pre-inst-env guix refresh -u emacs idutils gcc@@4.8 @end example @noindent The command above specifically updates the @code{emacs} and @code{idutils} packages. The @option{--select} option would have no effect in this case. When considering whether to upgrade a package, it is sometimes convenient to know which packages would be affected by the upgrade and should be checked for compatibility. For this the following option may be used when passing @command{guix refresh} one or more package names: @table @code @item --list-updaters @itemx -L List available updaters and exit (see @option{--type} above). For each updater, display the fraction of packages it covers; at the end, display the fraction of packages covered by all these updaters. @item --list-dependent @itemx -l List top-level dependent packages that would need to be rebuilt as a result of upgrading one or more packages. @xref{Invoking guix graph, the @code{reverse-package} type of @command{guix graph}}, for information on how to visualize the list of dependents of a package. @end table Be aware that the @option{--list-dependent} option only @emph{approximates} the rebuilds that would be required as a result of an upgrade. More rebuilds might be required under some circumstances. @example $ guix refresh --list-dependent flex Building the following 120 packages would ensure 213 dependent packages are rebuilt: hop@@2.4.0 geiser@@0.4 notmuch@@0.18 mu@@0.9.9.5 cflow@@1.4 idutils@@4.6 @dots{} @end example The command above lists a set of packages that could be built to check for compatibility with an upgraded @code{flex} package. @table @code @item --list-transitive List all the packages which one or more packages depend upon. @example $ guix refresh --list-transitive flex flex@@2.6.4 depends on the following 25 packages: perl@@5.28.0 help2man@@1.47.6 bison@@3.0.5 indent@@2.2.10 tar@@1.30 gzip@@1.9 bzip2@@1.0.6 xz@@5.2.4 file@@5.33 @dots{} @end example @end table The command above lists a set of packages which, when changed, would cause @code{flex} to be rebuilt. The following options can be used to customize GnuPG operation: @table @code @item --gpg=@var{command} Use @var{command} as the GnuPG 2.x command. @var{command} is searched for in @code{$PATH}. @item --keyring=@var{file} Use @var{file} as the keyring for upstream keys. @var{file} must be in the @dfn{keybox format}. Keybox files usually have a name ending in @file{.kbx} and the GNU@tie{}Privacy Guard (GPG) can manipulate these files (@pxref{kbxutil, @command{kbxutil},, gnupg, Using the GNU Privacy Guard}, for information on a tool to manipulate keybox files). When this option is omitted, @command{guix refresh} uses @file{~/.config/guix/upstream/trustedkeys.kbx} as the keyring for upstream signing keys. OpenPGP signatures are checked against keys from this keyring; missing keys are downloaded to this keyring as well (see @option{--key-download} below). You can export keys from your default GPG keyring into a keybox file using commands like this one: @example gpg --export rms@@gnu.org | kbxutil --import-openpgp >> mykeyring.kbx @end example Likewise, you can fetch keys to a specific keybox file like this: @example gpg --no-default-keyring --keyring mykeyring.kbx \ --recv-keys @value{OPENPGP-SIGNING-KEY-ID} @end example @ref{GPG Configuration Options, @option{--keyring},, gnupg, Using the GNU Privacy Guard}, for more information on GPG's @option{--keyring} option. @item --key-download=@var{policy} Handle missing OpenPGP keys according to @var{policy}, which may be one of: @table @code @item always Always download missing OpenPGP keys from the key server, and add them to the user's GnuPG keyring. @item never Never try to download missing OpenPGP keys. Instead just bail out. @item interactive When a package signed with an unknown OpenPGP key is encountered, ask the user whether to download it or not. This is the default behavior. @end table @item --key-server=@var{host} Use @var{host} as the OpenPGP key server when importing a public key. @item --load-path=@var{directory} Add @var{directory} to the front of the package module search path (@pxref{Package Modules}). This allows users to define their own packages and make them visible to the command-line tools. @end table The @code{github} updater uses the @uref{https://developer.github.com/v3/, GitHub API} to query for new releases. When used repeatedly e.g.@: when refreshing all packages, GitHub will eventually refuse to answer any further API requests. By default 60 API requests per hour are allowed, and a full refresh on all GitHub packages in Guix requires more than this. Authentication with GitHub through the use of an API token alleviates these limits. To use an API token, set the environment variable @env{GUIX_GITHUB_TOKEN} to a token procured from @uref{https://github.com/settings/tokens} or otherwise. @node Invoking guix lint @section Invoking @command{guix lint} @cindex @command{guix lint} @cindex package, checking for errors The @command{guix lint} command is meant to help package developers avoid common errors and use a consistent style. It runs a number of checks on a given set of packages in order to find common mistakes in their definitions. Available @dfn{checkers} include (see @option{--list-checkers} for a complete list): @table @code @item synopsis @itemx description Validate certain typographical and stylistic rules about package descriptions and synopses. @item inputs-should-be-native Identify inputs that should most likely be native inputs. @item source @itemx home-page @itemx mirror-url @itemx github-url @itemx source-file-name Probe @code{home-page} and @code{source} URLs and report those that are invalid. Suggest a @code{mirror://} URL when applicable. If the @code{source} URL redirects to a GitHub URL, recommend usage of the GitHub URL. Check that the source file name is meaningful, e.g.@: is not just a version number or ``git-checkout'', without a declared @code{file-name} (@pxref{origin Reference}). @item source-unstable-tarball Parse the @code{source} URL to determine if a tarball from GitHub is autogenerated or if it is a release tarball. Unfortunately GitHub's autogenerated tarballs are sometimes regenerated. @item derivation Check that the derivation of the given packages can be successfully computed for all the supported systems (@pxref{Derivations}). @item profile-collisions Check whether installing the given packages in a profile would lead to collisions. Collisions occur when several packages with the same name but a different version or a different store file name are propagated. @xref{package Reference, @code{propagated-inputs}}, for more information on propagated inputs. @item archival @cindex Software Heritage, source code archive @cindex archival of source code, Software Heritage Checks whether the package's source code is archived at @uref{https://www.softwareheritage.org, Software Heritage}. When the source code that is not archived comes from a version-control system (VCS)---e.g., it's obtained with @code{git-fetch}, send Software Heritage a ``save'' request so that it eventually archives it. This ensures that the source will remain available in the long term, and that Guix can fall back to Software Heritage should the source code disappear from its original host. The status of recent ``save'' requests can be @uref{https://archive.softwareheritage.org/save/#requests, viewed on-line}. When source code is a tarball obtained with @code{url-fetch}, simply print a message when it is not archived. As of this writing, Software Heritage does not allow requests to save arbitrary tarballs; we are working on ways to ensure that non-VCS source code is also archived. Software Heritage @uref{https://archive.softwareheritage.org/api/#rate-limiting, limits the request rate per IP address}. When the limit is reached, @command{guix lint} prints a message and the @code{archival} checker stops doing anything until that limit has been reset. @item cve @cindex security vulnerabilities @cindex CVE, Common Vulnerabilities and Exposures Report known vulnerabilities found in the Common Vulnerabilities and Exposures (CVE) databases of the current and past year @uref{https://nvd.nist.gov/vuln/data-feeds, published by the US NIST}. To view information about a particular vulnerability, visit pages such as: @itemize @item @indicateurl{https://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-YYYY-ABCD} @item @indicateurl{https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-YYYY-ABCD} @end itemize @noindent where @code{CVE-YYYY-ABCD} is the CVE identifier---e.g., @code{CVE-2015-7554}. Package developers can specify in package recipes the @uref{https://nvd.nist.gov/products/cpe,Common Platform Enumeration (CPE)} name and version of the package when they differ from the name or version that Guix uses, as in this example: @lisp (package (name "grub") ;; @dots{} ;; CPE calls this package "grub2". (properties '((cpe-name . "grub2") (cpe-version . "2.3")))) @end lisp @c See . Some entries in the CVE database do not specify which version of a package they apply to, and would thus ``stick around'' forever. Package developers who found CVE alerts and verified they can be ignored can declare them as in this example: @lisp (package (name "t1lib") ;; @dots{} ;; These CVEs no longer apply and can be safely ignored. (properties `((lint-hidden-cve . ("CVE-2011-0433" "CVE-2011-1553" "CVE-2011-1554" "CVE-2011-5244"))))) @end lisp @item formatting Warn about obvious source code formatting issues: trailing white space, use of tabulations, etc. @end table The general syntax is: @example guix lint @var{options} @var{package}@dots{} @end example If no package is given on the command line, then all packages are checked. The @var{options} may be zero or more of the following: @table @code @item --list-checkers @itemx -l List and describe all the available checkers that will be run on packages and exit. @item --checkers @itemx -c Only enable the checkers specified in a comma-separated list using the names returned by @option{--list-checkers}. @item --exclude @itemx -x Only disable the checkers specified in a comma-separated list using the names returned by @option{--list-checkers}. @item --no-network @itemx -n Only enable the checkers that do not depend on Internet access. @item --load-path=@var{directory} @itemx -L @var{directory} Add @var{directory} to the front of the package module search path (@pxref{Package Modules}). This allows users to define their own packages and make them visible to the command-line tools. @end table @node Invoking guix size @section Invoking @command{guix size} @cindex size @cindex package size @cindex closure @cindex @command{guix size} The @command{guix size} command helps package developers profile the disk usage of packages. It is easy to overlook the impact of an additional dependency added to a package, or the impact of using a single output for a package that could easily be split (@pxref{Packages with Multiple Outputs}). Such are the typical issues that @command{guix size} can highlight. The command can be passed one or more package specifications such as @code{gcc@@4.8} or @code{guile:debug}, or a file name in the store. Consider this example: @example $ guix size coreutils store item total self /gnu/store/@dots{}-gcc-5.5.0-lib 60.4 30.1 38.1% /gnu/store/@dots{}-glibc-2.27 30.3 28.8 36.6% /gnu/store/@dots{}-coreutils-8.28 78.9 15.0 19.0% /gnu/store/@dots{}-gmp-6.1.2 63.1 2.7 3.4% /gnu/store/@dots{}-bash-static-4.4.12 1.5 1.5 1.9% /gnu/store/@dots{}-acl-2.2.52 61.1 0.4 0.5% /gnu/store/@dots{}-attr-2.4.47 60.6 0.2 0.3% /gnu/store/@dots{}-libcap-2.25 60.5 0.2 0.2% total: 78.9 MiB @end example @cindex closure The store items listed here constitute the @dfn{transitive closure} of Coreutils---i.e., Coreutils and all its dependencies, recursively---as would be returned by: @example $ guix gc -R /gnu/store/@dots{}-coreutils-8.23 @end example Here the output shows three columns next to store items. The first column, labeled ``total'', shows the size in mebibytes (MiB) of the closure of the store item---that is, its own size plus the size of all its dependencies. The next column, labeled ``self'', shows the size of the item itself. The last column shows the ratio of the size of the item itself to the space occupied by all the items listed here. In this example, we see that the closure of Coreutils weighs in at 79@tie{}MiB, most of which is taken by libc and GCC's run-time support libraries. (That libc and GCC's libraries represent a large fraction of the closure is not a problem @i{per se} because they are always available on the system anyway.) Since the command also accepts store file names, assessing the size of a build result is straightforward: @example guix size $(guix system build config.scm) @end example When the package(s) passed to @command{guix size} are available in the store@footnote{More precisely, @command{guix size} looks for the @emph{ungrafted} variant of the given package(s), as returned by @code{guix build @var{package} --no-grafts}. @xref{Security Updates}, for information on grafts.}, @command{guix size} queries the daemon to determine its dependencies, and measures its size in the store, similar to @command{du -ms --apparent-size} (@pxref{du invocation,,, coreutils, GNU Coreutils}). When the given packages are @emph{not} in the store, @command{guix size} reports information based on the available substitutes (@pxref{Substitutes}). This makes it possible it to profile disk usage of store items that are not even on disk, only available remotely. You can also specify several package names: @example $ guix size coreutils grep sed bash store item total self /gnu/store/@dots{}-coreutils-8.24 77.8 13.8 13.4% /gnu/store/@dots{}-grep-2.22 73.1 0.8 0.8% /gnu/store/@dots{}-bash-4.3.42 72.3 4.7 4.6% /gnu/store/@dots{}-readline-6.3 67.6 1.2 1.2% @dots{} total: 102.3 MiB @end example @noindent In this example we see that the combination of the four packages takes 102.3@tie{}MiB in total, which is much less than the sum of each closure since they have a lot of dependencies in common. When looking at the profile returned by @command{guix size}, you may find yourself wondering why a given package shows up in the profile at all. To understand it, you can use @command{guix graph --path -t references} to display the shortest path between the two packages (@pxref{Invoking guix graph}). The available options are: @table @option @item --substitute-urls=@var{urls} Use substitute information from @var{urls}. @xref{client-substitute-urls, the same option for @code{guix build}}. @item --sort=@var{key} Sort lines according to @var{key}, one of the following options: @table @code @item self the size of each item (the default); @item closure the total size of the item's closure. @end table @item --map-file=@var{file} Write a graphical map of disk usage in PNG format to @var{file}. For the example above, the map looks like this: @image{images/coreutils-size-map,5in,, map of Coreutils disk usage produced by @command{guix size}} This option requires that @uref{https://wingolog.org/software/guile-charting/, Guile-Charting} be installed and visible in Guile's module search path. When that is not the case, @command{guix size} fails as it tries to load it. @item --system=@var{system} @itemx -s @var{system} Consider packages for @var{system}---e.g., @code{x86_64-linux}. @item --load-path=@var{directory} @itemx -L @var{directory} Add @var{directory} to the front of the package module search path (@pxref{Package Modules}). This allows users to define their own packages and make them visible to the command-line tools. @end table @node Invoking guix graph @section Invoking @command{guix graph} @cindex DAG @cindex @command{guix graph} @cindex package dependencies Packages and their dependencies form a @dfn{graph}, specifically a directed acyclic graph (DAG). It can quickly become difficult to have a mental model of the package DAG, so the @command{guix graph} command provides a visual representation of the DAG. By default, @command{guix graph} emits a DAG representation in the input format of @uref{https://www.graphviz.org/, Graphviz}, so its output can be passed directly to the @command{dot} command of Graphviz. It can also emit an HTML page with embedded JavaScript code to display a ``chord diagram'' in a Web browser, using the @uref{https://d3js.org/, d3.js} library, or emit Cypher queries to construct a graph in a graph database supporting the @uref{https://www.opencypher.org/, openCypher} query language. With @option{--path}, it simply displays the shortest path between two packages. The general syntax is: @example guix graph @var{options} @var{package}@dots{} @end example For example, the following command generates a PDF file representing the package DAG for the GNU@tie{}Core Utilities, showing its build-time dependencies: @example guix graph coreutils | dot -Tpdf > dag.pdf @end example The output looks like this: @image{images/coreutils-graph,2in,,Dependency graph of the GNU Coreutils} Nice little graph, no? You may find it more pleasant to navigate the graph interactively with @command{xdot} (from the @code{xdot} package): @example guix graph coreutils | xdot - @end example But there is more than one graph! The one above is concise: it is the graph of package objects, omitting implicit inputs such as GCC, libc, grep, etc. It is often useful to have such a concise graph, but sometimes one may want to see more details. @command{guix graph} supports several types of graphs, allowing you to choose the level of detail: @table @code @item package This is the default type used in the example above. It shows the DAG of package objects, excluding implicit dependencies. It is concise, but filters out many details. @item reverse-package This shows the @emph{reverse} DAG of packages. For example: @example guix graph --type=reverse-package ocaml @end example ...@: yields the graph of packages that @emph{explicitly} depend on OCaml (if you are also interested in cases where OCaml is an implicit dependency, see @code{reverse-bag} below). Note that for core packages this can yield huge graphs. If all you want is to know the number of packages that depend on a given package, use @command{guix refresh --list-dependent} (@pxref{Invoking guix refresh, @option{--list-dependent}}). @item bag-emerged This is the package DAG, @emph{including} implicit inputs. For instance, the following command: @example guix graph --type=bag-emerged coreutils @end example ...@: yields this bigger graph: @image{images/coreutils-bag-graph,,5in,Detailed dependency graph of the GNU Coreutils} At the bottom of the graph, we see all the implicit inputs of @var{gnu-build-system} (@pxref{Build Systems, @code{gnu-build-system}}). Now, note that the dependencies of these implicit inputs---that is, the @dfn{bootstrap dependencies} (@pxref{Bootstrapping})---are not shown here, for conciseness. @item bag Similar to @code{bag-emerged}, but this time including all the bootstrap dependencies. @item bag-with-origins Similar to @code{bag}, but also showing origins and their dependencies. @item reverse-bag This shows the @emph{reverse} DAG of packages. Unlike @code{reverse-package}, it also takes implicit dependencies into account. For example: @example guix graph -t reverse-bag dune @end example @noindent ...@: yields the graph of all packages that depend on Dune, directly or indirectly. Since Dune is an @emph{implicit} dependency of many packages @i{via} @code{dune-build-system}, this shows a large number of packages, whereas @code{reverse-package} would show very few if any. @item derivation This is the most detailed representation: It shows the DAG of derivations (@pxref{Derivations}) and plain store items. Compared to the above representation, many additional nodes are visible, including build scripts, patches, Guile modules, etc. For this type of graph, it is also possible to pass a @file{.drv} file name instead of a package name, as in: @example guix graph -t derivation `guix system build -d my-config.scm` @end example @item module This is the graph of @dfn{package modules} (@pxref{Package Modules}). For example, the following command shows the graph for the package module that defines the @code{guile} package: @example guix graph -t module guile | xdot - @end example @end table All the types above correspond to @emph{build-time dependencies}. The following graph type represents the @emph{run-time dependencies}: @table @code @item references This is the graph of @dfn{references} of a package output, as returned by @command{guix gc --references} (@pxref{Invoking guix gc}). If the given package output is not available in the store, @command{guix graph} attempts to obtain dependency information from substitutes. Here you can also pass a store file name instead of a package name. For example, the command below produces the reference graph of your profile (which can be big!): @example guix graph -t references `readlink -f ~/.guix-profile` @end example @item referrers This is the graph of the @dfn{referrers} of a store item, as returned by @command{guix gc --referrers} (@pxref{Invoking guix gc}). This relies exclusively on local information from your store. For instance, let us suppose that the current Inkscape is available in 10 profiles on your machine; @command{guix graph -t referrers inkscape} will show a graph rooted at Inkscape and with those 10 profiles linked to it. It can help determine what is preventing a store item from being garbage collected. @end table @cindex shortest path, between packages Often, the graph of the package you are interested in does not fit on your screen, and anyway all you want to know is @emph{why} that package actually depends on some seemingly unrelated package. The @option{--path} option instructs @command{guix graph} to display the shortest path between two packages (or derivations, or store items, etc.): @example $ guix graph --path emacs libunistring emacs@@26.3 mailutils@@3.9 libunistring@@0.9.10 $ guix graph --path -t derivation emacs libunistring /gnu/store/@dots{}-emacs-26.3.drv /gnu/store/@dots{}-mailutils-3.9.drv /gnu/store/@dots{}-libunistring-0.9.10.drv $ guix graph --path -t references emacs libunistring /gnu/store/@dots{}-emacs-26.3 /gnu/store/@dots{}-libidn2-2.2.0 /gnu/store/@dots{}-libunistring-0.9.10 @end example The available options are the following: @table @option @item --type=@var{type} @itemx -t @var{type} Produce a graph output of @var{type}, where @var{type} must be one of the values listed above. @item --list-types List the supported graph types. @item --backend=@var{backend} @itemx -b @var{backend} Produce a graph using the selected @var{backend}. @item --list-backends List the supported graph backends. Currently, the available backends are Graphviz and d3.js. @item --path Display the shortest path between two nodes of the type specified by @option{--type}. The example below shows the shortest path between @code{libreoffice} and @code{llvm} according to the references of @code{libreoffice}: @example $ guix graph --path -t references libreoffice llvm /gnu/store/@dots{}-libreoffice-6.4.2.2 /gnu/store/@dots{}-libepoxy-1.5.4 /gnu/store/@dots{}-mesa-19.3.4 /gnu/store/@dots{}-llvm-9.0.1 @end example @item --expression=@var{expr} @itemx -e @var{expr} Consider the package @var{expr} evaluates to. This is useful to precisely refer to a package, as in this example: @example guix graph -e '(@@@@ (gnu packages commencement) gnu-make-final)' @end example @item --system=@var{system} @itemx -s @var{system} Display the graph for @var{system}---e.g., @code{i686-linux}. The package dependency graph is largely architecture-independent, but there are some architecture-dependent bits that this option allows you to visualize. @item --load-path=@var{directory} @itemx -L @var{directory} Add @var{directory} to the front of the package module search path (@pxref{Package Modules}). This allows users to define their own packages and make them visible to the command-line tools. @end table On top of that, @command{guix graph} supports all the usual package transformation options (@pxref{Package Transformation Options}). This makes it easy to view the effect of a graph-rewriting transformation such as @option{--with-input}. For example, the command below outputs the graph of @code{git} once @code{openssl} has been replaced by @code{libressl} everywhere in the graph: @example guix graph git --with-input=openssl=libressl @end example So many possibilities, so much fun! @node Invoking guix publish @section Invoking @command{guix publish} @cindex @command{guix publish} The purpose of @command{guix publish} is to enable users to easily share their store with others, who can then use it as a substitute server (@pxref{Substitutes}). When @command{guix publish} runs, it spawns an HTTP server which allows anyone with network access to obtain substitutes from it. This means that any machine running Guix can also act as if it were a build farm, since the HTTP interface is compatible with Cuirass, the software behind the @code{@value{SUBSTITUTE-SERVER}} build farm. For security, each substitute is signed, allowing recipients to check their authenticity and integrity (@pxref{Substitutes}). Because @command{guix publish} uses the signing key of the system, which is only readable by the system administrator, it must be started as root; the @option{--user} option makes it drop root privileges early on. The signing key pair must be generated before @command{guix publish} is launched, using @command{guix archive --generate-key} (@pxref{Invoking guix archive}). When the @option{--advertise} option is passed, the server advertises its availability on the local network using multicast DNS (mDNS) and DNS service discovery (DNS-SD), currently @i{via} Guile-Avahi (@pxref{Top,,, guile-avahi, Using Avahi in Guile Scheme Programs}). The general syntax is: @example guix publish @var{options}@dots{} @end example Running @command{guix publish} without any additional arguments will spawn an HTTP server on port 8080: @example guix publish @end example Once a publishing server has been authorized, the daemon may download substitutes from it. @xref{Getting Substitutes from Other Servers}. By default, @command{guix publish} compresses archives on the fly as it serves them. This ``on-the-fly'' mode is convenient in that it requires no setup and is immediately available. However, when serving lots of clients, we recommend using the @option{--cache} option, which enables caching of the archives before they are sent to clients---see below for details. The @command{guix weather} command provides a handy way to check what a server provides (@pxref{Invoking guix weather}). As a bonus, @command{guix publish} also serves as a content-addressed mirror for source files referenced in @code{origin} records (@pxref{origin Reference}). For instance, assuming @command{guix publish} is running on @code{example.org}, the following URL returns the raw @file{hello-2.10.tar.gz} file with the given SHA256 hash (represented in @code{nix-base32} format, @pxref{Invoking guix hash}): @example http://example.org/file/hello-2.10.tar.gz/sha256/0ssi1@dots{}ndq1i @end example Obviously, these URLs only work for files that are in the store; in other cases, they return 404 (``Not Found''). @cindex build logs, publication Build logs are available from @code{/log} URLs like: @example http://example.org/log/gwspk@dots{}-guile-2.2.3 @end example @noindent When @command{guix-daemon} is configured to save compressed build logs, as is the case by default (@pxref{Invoking guix-daemon}), @code{/log} URLs return the compressed log as-is, with an appropriate @code{Content-Type} and/or @code{Content-Encoding} header. We recommend running @command{guix-daemon} with @option{--log-compression=gzip} since Web browsers can automatically decompress it, which is not the case with Bzip2 compression. The following options are available: @table @code @item --port=@var{port} @itemx -p @var{port} Listen for HTTP requests on @var{port}. @item --listen=@var{host} Listen on the network interface for @var{host}. The default is to accept connections from any interface. @item --user=@var{user} @itemx -u @var{user} Change privileges to @var{user} as soon as possible---i.e., once the server socket is open and the signing key has been read. @item --compression[=@var{method}[:@var{level}]] @itemx -C [@var{method}[:@var{level}]] Compress data using the given @var{method} and @var{level}. @var{method} is one of @code{lzip}, @code{zstd}, and @code{gzip}; when @var{method} is omitted, @code{gzip} is used. When @var{level} is zero, disable compression. The range 1 to 9 corresponds to different compression levels: 1 is the fastest, and 9 is the best (CPU-intensive). The default is 3. Usually, @code{lzip} compresses noticeably better than @code{gzip} for a small increase in CPU usage; see @uref{https://nongnu.org/lzip/lzip_benchmark.html,benchmarks on the lzip Web page}. However, @code{lzip} achieves low decompression throughput (on the order of 50@tie{}MiB/s on modern hardware), which can be a bottleneck for someone who downloads over a fast network connection. The compression ratio of @code{zstd} is between that of @code{lzip} and that of @code{gzip}; its main advantage is a @uref{https://facebook.github.io/zstd/,high decompression speed}. Unless @option{--cache} is used, compression occurs on the fly and the compressed streams are not cached. Thus, to reduce load on the machine that runs @command{guix publish}, it may be a good idea to choose a low compression level, to run @command{guix publish} behind a caching proxy, or to use @option{--cache}. Using @option{--cache} has the advantage that it allows @command{guix publish} to add @code{Content-Length} HTTP header to its responses. This option can be repeated, in which case every substitute gets compressed using all the selected methods, and all of them are advertised. This is useful when users may not support all the compression methods: they can select the one they support. @item --cache=@var{directory} @itemx -c @var{directory} Cache archives and meta-data (@code{.narinfo} URLs) to @var{directory} and only serve archives that are in cache. When this option is omitted, archives and meta-data are created on-the-fly. This can reduce the available bandwidth, especially when compression is enabled, since this may become CPU-bound. Another drawback of the default mode is that the length of archives is not known in advance, so @command{guix publish} does not add a @code{Content-Length} HTTP header to its responses, which in turn prevents clients from knowing the amount of data being downloaded. Conversely, when @option{--cache} is used, the first request for a store item (@i{via} a @code{.narinfo} URL) triggers a background process to @dfn{bake} the archive---computing its @code{.narinfo} and compressing the archive, if needed. Once the archive is cached in @var{directory}, subsequent requests succeed and are served directly from the cache, which guarantees that clients get the best possible bandwidth. That first @code{.narinfo} request nonetheless returns 200, provided the requested store item is ``small enough'', below the cache bypass threshold---see @option{--cache-bypass-threshold} below. That way, clients do not have to wait until the archive is baked. For larger store items, the first @code{.narinfo} request returns 404, meaning that clients have to wait until the archive is baked. The ``baking'' process is performed by worker threads. By default, one thread per CPU core is created, but this can be customized. See @option{--workers} below. When @option{--ttl} is used, cached entries are automatically deleted when they have expired. @item --workers=@var{N} When @option{--cache} is used, request the allocation of @var{N} worker threads to ``bake'' archives. @item --ttl=@var{ttl} Produce @code{Cache-Control} HTTP headers that advertise a time-to-live (TTL) of @var{ttl}. @var{ttl} must denote a duration: @code{5d} means 5 days, @code{1m} means 1 month, and so on. This allows the user's Guix to keep substitute information in cache for @var{ttl}. However, note that @code{guix publish} does not itself guarantee that the store items it provides will indeed remain available for as long as @var{ttl}. Additionally, when @option{--cache} is used, cached entries that have not been accessed for @var{ttl} and that no longer have a corresponding item in the store, may be deleted. @item --cache-bypass-threshold=@var{size} When used in conjunction with @option{--cache}, store items smaller than @var{size} are immediately available, even when they are not yet in cache. @var{size} is a size in bytes, or it can be suffixed by @code{M} for megabytes and so on. The default is @code{10M}. ``Cache bypass'' allows you to reduce the publication delay for clients at the expense of possibly additional I/O and CPU use on the server side: depending on the client access patterns, those store items can end up being baked several times until a copy is available in cache. Increasing the threshold may be useful for sites that have few users, or to guarantee that users get substitutes even for store items that are not popular. @item --nar-path=@var{path} Use @var{path} as the prefix for the URLs of ``nar'' files (@pxref{Invoking guix archive, normalized archives}). By default, nars are served at a URL such as @code{/nar/gzip/@dots{}-coreutils-8.25}. This option allows you to change the @code{/nar} part to @var{path}. @item --public-key=@var{file} @itemx --private-key=@var{file} Use the specific @var{file}s as the public/private key pair used to sign the store items being published. The files must correspond to the same key pair (the private key is used for signing and the public key is merely advertised in the signature metadata). They must contain keys in the canonical s-expression format as produced by @command{guix archive --generate-key} (@pxref{Invoking guix archive}). By default, @file{/etc/guix/signing-key.pub} and @file{/etc/guix/signing-key.sec} are used. @item --repl[=@var{port}] @itemx -r [@var{port}] Spawn a Guile REPL server (@pxref{REPL Servers,,, guile, GNU Guile Reference Manual}) on @var{port} (37146 by default). This is used primarily for debugging a running @command{guix publish} server. @end table Enabling @command{guix publish} on Guix System is a one-liner: just instantiate a @code{guix-publish-service-type} service in the @code{services} field of the @code{operating-system} declaration (@pxref{guix-publish-service-type, @code{guix-publish-service-type}}). If you are instead running Guix on a ``foreign distro'', follow these instructions: @itemize @item If your host distro uses the systemd init system: @example # ln -s ~root/.guix-profile/lib/systemd/system/guix-publish.service \ /etc/systemd/system/ # systemctl start guix-publish && systemctl enable guix-publish @end example @item If your host distro uses the Upstart init system: @example # ln -s ~root/.guix-profile/lib/upstart/system/guix-publish.conf /etc/init/ # start guix-publish @end example @item Otherwise, proceed similarly with your distro's init system. @end itemize @node Invoking guix challenge @section Invoking @command{guix challenge} @cindex reproducible builds @cindex verifiable builds @cindex @command{guix challenge} @cindex challenge Do the binaries provided by this server really correspond to the source code it claims to build? Is a package build process deterministic? These are the questions the @command{guix challenge} command attempts to answer. The former is obviously an important question: Before using a substitute server (@pxref{Substitutes}), one had better @emph{verify} that it provides the right binaries, and thus @emph{challenge} it. The latter is what enables the former: If package builds are deterministic, then independent builds of the package should yield the exact same result, bit for bit; if a server provides a binary different from the one obtained locally, it may be either corrupt or malicious. We know that the hash that shows up in @file{/gnu/store} file names is the hash of all the inputs of the process that built the file or directory---compilers, libraries, build scripts, etc. (@pxref{Introduction}). Assuming deterministic build processes, one store file name should map to exactly one build output. @command{guix challenge} checks whether there is, indeed, a single mapping by comparing the build outputs of several independent builds of any given store item. The command output looks like this: @smallexample $ guix challenge --substitute-urls="https://@value{SUBSTITUTE-SERVER} https://guix.example.org" updating list of substitutes from 'https://@value{SUBSTITUTE-SERVER}'... 100.0% updating list of substitutes from 'https://guix.example.org'... 100.0% /gnu/store/@dots{}-openssl-1.0.2d contents differ: local hash: 0725l22r5jnzazaacncwsvp9kgf42266ayyp814v7djxs7nk963q https://@value{SUBSTITUTE-SERVER}/nar/@dots{}-openssl-1.0.2d: 0725l22r5jnzazaacncwsvp9kgf42266ayyp814v7djxs7nk963q https://guix.example.org/nar/@dots{}-openssl-1.0.2d: 1zy4fmaaqcnjrzzajkdn3f5gmjk754b43qkq47llbyak9z0qjyim differing files: /lib/libcrypto.so.1.1 /lib/libssl.so.1.1 /gnu/store/@dots{}-git-2.5.0 contents differ: local hash: 00p3bmryhjxrhpn2gxs2fy0a15lnip05l97205pgbk5ra395hyha https://@value{SUBSTITUTE-SERVER}/nar/@dots{}-git-2.5.0: 069nb85bv4d4a6slrwjdy8v1cn4cwspm3kdbmyb81d6zckj3nq9f https://guix.example.org/nar/@dots{}-git-2.5.0: 0mdqa9w1p6cmli6976v4wi0sw9r4p5prkj7lzfd1877wk11c9c73 differing file: /libexec/git-core/git-fsck /gnu/store/@dots{}-pius-2.1.1 contents differ: local hash: 0k4v3m9z1zp8xzzizb7d8kjj72f9172xv078sq4wl73vnq9ig3ax https://@value{SUBSTITUTE-SERVER}/nar/@dots{}-pius-2.1.1: 0k4v3m9z1zp8xzzizb7d8kjj72f9172xv078sq4wl73vnq9ig3ax https://guix.example.org/nar/@dots{}-pius-2.1.1: 1cy25x1a4fzq5rk0pmvc8xhwyffnqz95h2bpvqsz2mpvlbccy0gs differing file: /share/man/man1/pius.1.gz @dots{} 6,406 store items were analyzed: - 4,749 (74.1%) were identical - 525 (8.2%) differed - 1,132 (17.7%) were inconclusive @end smallexample @noindent In this example, @command{guix challenge} first scans the store to determine the set of locally-built derivations---as opposed to store items that were downloaded from a substitute server---and then queries all the substitute servers. It then reports those store items for which the servers obtained a result different from the local build. @cindex non-determinism, in package builds As an example, @code{guix.example.org} always gets a different answer. Conversely, @code{@value{SUBSTITUTE-SERVER}} agrees with local builds, except in the case of Git. This might indicate that the build process of Git is non-deterministic, meaning that its output varies as a function of various things that Guix does not fully control, in spite of building packages in isolated environments (@pxref{Features}). Most common sources of non-determinism include the addition of timestamps in build results, the inclusion of random numbers, and directory listings sorted by inode number. See @uref{https://reproducible-builds.org/docs/}, for more information. To find out what is wrong with this Git binary, the easiest approach is to run: @example guix challenge git \ --diff=diffoscope \ --substitute-urls="https://@value{SUBSTITUTE-SERVER} https://guix.example.org" @end example This automatically invokes @command{diffoscope}, which displays detailed information about files that differ. Alternatively, we can do something along these lines (@pxref{Invoking guix archive}): @example $ wget -q -O - https://@value{SUBSTITUTE-SERVER}/nar/lzip/@dots{}-git-2.5.0 \ | lzip -d | guix archive -x /tmp/git $ diff -ur --no-dereference /gnu/store/@dots{}-git.2.5.0 /tmp/git @end example This command shows the difference between the files resulting from the local build, and the files resulting from the build on @code{@value{SUBSTITUTE-SERVER}} (@pxref{Overview, Comparing and Merging Files,, diffutils, Comparing and Merging Files}). The @command{diff} command works great for text files. When binary files differ, a better option is @uref{https://diffoscope.org/, Diffoscope}, a tool that helps visualize differences for all kinds of files. Once you have done that work, you can tell whether the differences are due to a non-deterministic build process or to a malicious server. We try hard to remove sources of non-determinism in packages to make it easier to verify substitutes, but of course, this is a process that involves not just Guix, but a large part of the free software community. In the meantime, @command{guix challenge} is one tool to help address the problem. If you are writing packages for Guix, you are encouraged to check whether @code{@value{SUBSTITUTE-SERVER}} and other substitute servers obtain the same build result as you did with: @example $ guix challenge @var{package} @end example @noindent where @var{package} is a package specification such as @code{guile@@2.0} or @code{glibc:debug}. The general syntax is: @example guix challenge @var{options} [@var{packages}@dots{}] @end example When a difference is found between the hash of a locally-built item and that of a server-provided substitute, or among substitutes provided by different servers, the command displays it as in the example above and its exit code is 2 (other non-zero exit codes denote other kinds of errors). The one option that matters is: @table @code @item --substitute-urls=@var{urls} Consider @var{urls} the whitespace-separated list of substitute source URLs to compare to. @item --diff=@var{mode} Upon mismatches, show differences according to @var{mode}, one of: @table @asis @item @code{simple} (the default) Show the list of files that differ. @item @code{diffoscope} @itemx @var{command} Invoke @uref{https://diffoscope.org/, Diffoscope}, passing it two directories whose contents do not match. When @var{command} is an absolute file name, run @var{command} instead of Diffoscope. @item @code{none} Do not show further details about the differences. @end table Thus, unless @option{--diff=none} is passed, @command{guix challenge} downloads the store items from the given substitute servers so that it can compare them. @item --verbose @itemx -v Show details about matches (identical contents) in addition to information about mismatches. @end table @node Invoking guix copy @section Invoking @command{guix copy} @cindex copy, of store items, over SSH @cindex SSH, copy of store items @cindex sharing store items across machines @cindex transferring store items across machines The @command{guix copy} command copies items from the store of one machine to that of another machine over a secure shell (SSH) connection@footnote{This command is available only when Guile-SSH was found. @xref{Requirements}, for details.}. For example, the following command copies the @code{coreutils} package, the user's profile, and all their dependencies over to @var{host}, logged in as @var{user}: @example guix copy --to=@var{user}@@@var{host} \ coreutils `readlink -f ~/.guix-profile` @end example If some of the items to be copied are already present on @var{host}, they are not actually sent. The command below retrieves @code{libreoffice} and @code{gimp} from @var{host}, assuming they are available there: @example guix copy --from=@var{host} libreoffice gimp @end example The SSH connection is established using the Guile-SSH client, which is compatible with OpenSSH: it honors @file{~/.ssh/known_hosts} and @file{~/.ssh/config}, and uses the SSH agent for authentication. The key used to sign items that are sent must be accepted by the remote machine. Likewise, the key used by the remote machine to sign items you are retrieving must be in @file{/etc/guix/acl} so it is accepted by your own daemon. @xref{Invoking guix archive}, for more information about store item authentication. The general syntax is: @example guix copy [--to=@var{spec}|--from=@var{spec}] @var{items}@dots{} @end example You must always specify one of the following options: @table @code @item --to=@var{spec} @itemx --from=@var{spec} Specify the host to send to or receive from. @var{spec} must be an SSH spec such as @code{example.org}, @code{charlie@@example.org}, or @code{charlie@@example.org:2222}. @end table The @var{items} can be either package names, such as @code{gimp}, or store items, such as @file{/gnu/store/@dots{}-idutils-4.6}. When specifying the name of a package to send, it is first built if needed, unless @option{--dry-run} was specified. Common build options are supported (@pxref{Common Build Options}). @node Invoking guix container @section Invoking @command{guix container} @cindex container @cindex @command{guix container} @quotation Note As of version @value{VERSION}, this tool is experimental. The interface is subject to radical change in the future. @end quotation The purpose of @command{guix container} is to manipulate processes running within an isolated environment, commonly known as a ``container'', typically created by the @command{guix environment} (@pxref{Invoking guix environment}) and @command{guix system container} (@pxref{Invoking guix system}) commands. The general syntax is: @example guix container @var{action} @var{options}@dots{} @end example @var{action} specifies the operation to perform with a container, and @var{options} specifies the context-specific arguments for the action. The following actions are available: @table @code @item exec Execute a command within the context of a running container. The syntax is: @example guix container exec @var{pid} @var{program} @var{arguments}@dots{} @end example @var{pid} specifies the process ID of the running container. @var{program} specifies an executable file name within the root file system of the container. @var{arguments} are the additional options that will be passed to @var{program}. The following command launches an interactive login shell inside a Guix system container, started by @command{guix system container}, and whose process ID is 9001: @example guix container exec 9001 /run/current-system/profile/bin/bash --login @end example Note that the @var{pid} cannot be the parent process of a container. It must be PID 1 of the container or one of its child processes. @end table @node Invoking guix weather @section Invoking @command{guix weather} Occasionally you're grumpy because substitutes are lacking and you end up building packages by yourself (@pxref{Substitutes}). The @command{guix weather} command reports on substitute availability on the specified servers so you can have an idea of whether you'll be grumpy today. It can sometimes be useful info as a user, but it is primarily useful to people running @command{guix publish} (@pxref{Invoking guix publish}). @cindex statistics, for substitutes @cindex availability of substitutes @cindex substitute availability @cindex weather, substitute availability Here's a sample run: @example $ guix weather --substitute-urls=https://guix.example.org computing 5,872 package derivations for x86_64-linux... looking for 6,128 store items on https://guix.example.org.. updating list of substitutes from 'https://guix.example.org'... 100.0% https://guix.example.org 43.4% substitutes available (2,658 out of 6,128) 7,032.5 MiB of nars (compressed) 19,824.2 MiB on disk (uncompressed) 0.030 seconds per request (182.9 seconds in total) 33.5 requests per second 9.8% (342 out of 3,470) of the missing items are queued 867 queued builds x86_64-linux: 518 (59.7%) i686-linux: 221 (25.5%) aarch64-linux: 128 (14.8%) build rate: 23.41 builds per hour x86_64-linux: 11.16 builds per hour i686-linux: 6.03 builds per hour aarch64-linux: 6.41 builds per hour @end example @cindex continuous integration, statistics As you can see, it reports the fraction of all the packages for which substitutes are available on the server---regardless of whether substitutes are enabled, and regardless of whether this server's signing key is authorized. It also reports the size of the compressed archives (``nars'') provided by the server, the size the corresponding store items occupy in the store (assuming deduplication is turned off), and the server's throughput. The second part gives continuous integration (CI) statistics, if the server supports it. In addition, using the @option{--coverage} option, @command{guix weather} can list ``important'' package substitutes missing on the server (see below). To achieve that, @command{guix weather} queries over HTTP(S) meta-data (@dfn{narinfos}) for all the relevant store items. Like @command{guix challenge}, it ignores signatures on those substitutes, which is innocuous since the command only gathers statistics and cannot install those substitutes. The general syntax is: @example guix weather @var{options}@dots{} [@var{packages}@dots{}] @end example When @var{packages} is omitted, @command{guix weather} checks the availability of substitutes for @emph{all} the packages, or for those specified with @option{--manifest}; otherwise it only considers the specified packages. It is also possible to query specific system types with @option{--system}. @command{guix weather} exits with a non-zero code when the fraction of available substitutes is below 100%. The available options are listed below. @table @code @item --substitute-urls=@var{urls} @var{urls} is the space-separated list of substitute server URLs to query. When this option is omitted, the default set of substitute servers is queried. @item --system=@var{system} @itemx -s @var{system} Query substitutes for @var{system}---e.g., @code{aarch64-linux}. This option can be repeated, in which case @command{guix weather} will query substitutes for several system types. @item --manifest=@var{file} Instead of querying substitutes for all the packages, only ask for those specified in @var{file}. @var{file} must contain a @dfn{manifest}, as with the @code{-m} option of @command{guix package} (@pxref{Invoking guix package}). This option can be repeated several times, in which case the manifests are concatenated. @item --coverage[=@var{count}] @itemx -c [@var{count}] Report on substitute coverage for packages: list packages with at least @var{count} dependents (zero by default) for which substitutes are unavailable. Dependent packages themselves are not listed: if @var{b} depends on @var{a} and @var{a} has no substitutes, only @var{a} is listed, even though @var{b} usually lacks substitutes as well. The result looks like this: @example $ guix weather --substitute-urls=@value{SUBSTITUTE-URL} -c 10 computing 8,983 package derivations for x86_64-linux... looking for 9,343 store items on @value{SUBSTITUTE-URL}... updating substitutes from '@value{SUBSTITUTE-URL}'... 100.0% @value{SUBSTITUTE-URL} 64.7% substitutes available (6,047 out of 9,343) @dots{} 2502 packages are missing from '@value{SUBSTITUTE-URL}' for 'x86_64-linux', among which: 58 kcoreaddons@@5.49.0 /gnu/store/@dots{}-kcoreaddons-5.49.0 46 qgpgme@@1.11.1 /gnu/store/@dots{}-qgpgme-1.11.1 37 perl-http-cookiejar@@0.008 /gnu/store/@dots{}-perl-http-cookiejar-0.008 @dots{} @end example What this example shows is that @code{kcoreaddons} and presumably the 58 packages that depend on it have no substitutes at @code{@value{SUBSTITUTE-SERVER}}; likewise for @code{qgpgme} and the 46 packages that depend on it. If you are a Guix developer, or if you are taking care of this build farm, you'll probably want to have a closer look at these packages: they may simply fail to build. @item --display-missing Display the list of store items for which substitutes are missing. @end table @node Invoking guix processes @section Invoking @command{guix processes} The @command{guix processes} command can be useful to developers and system administrators, especially on multi-user machines and on build farms: it lists the current sessions (connections to the daemon), as well as information about the processes involved@footnote{Remote sessions, when @command{guix-daemon} is started with @option{--listen} specifying a TCP endpoint, are @emph{not} listed.}. Here's an example of the information it returns: @example $ sudo guix processes SessionPID: 19002 ClientPID: 19090 ClientCommand: guix environment --ad-hoc python SessionPID: 19402 ClientPID: 19367 ClientCommand: guix publish -u guix-publish -p 3000 -C 9 @dots{} SessionPID: 19444 ClientPID: 19419 ClientCommand: cuirass --cache-directory /var/cache/cuirass @dots{} LockHeld: /gnu/store/@dots{}-perl-ipc-cmd-0.96.lock LockHeld: /gnu/store/@dots{}-python-six-bootstrap-1.11.0.lock LockHeld: /gnu/store/@dots{}-libjpeg-turbo-2.0.0.lock ChildPID: 20495 ChildCommand: guix offload x86_64-linux 7200 1 28800 ChildPID: 27733 ChildCommand: guix offload x86_64-linux 7200 1 28800 ChildPID: 27793 ChildCommand: guix offload x86_64-linux 7200 1 28800 @end example In this example we see that @command{guix-daemon} has three clients: @command{guix environment}, @command{guix publish}, and the Cuirass continuous integration tool; their process identifier (PID) is given by the @code{ClientPID} field. The @code{SessionPID} field gives the PID of the @command{guix-daemon} sub-process of this particular session. The @code{LockHeld} fields show which store items are currently locked by this session, which corresponds to store items being built or substituted (the @code{LockHeld} field is not displayed when @command{guix processes} is not running as root). Last, by looking at the @code{ChildPID} and @code{ChildCommand} fields, we understand that these three builds are being offloaded (@pxref{Daemon Offload Setup}). The output is in Recutils format so we can use the handy @command{recsel} command to select sessions of interest (@pxref{Selection Expressions,,, recutils, GNU recutils manual}). As an example, the command shows the command line and PID of the client that triggered the build of a Perl package: @example $ sudo guix processes | \ recsel -p ClientPID,ClientCommand -e 'LockHeld ~ "perl"' ClientPID: 19419 ClientCommand: cuirass --cache-directory /var/cache/cuirass @dots{} @end example Additional options are listed below. @table @code @item --format=@var{format} @itemx -f @var{format} Produce output in the specified @var{format}, one of: @table @code @item recutils The default option. It outputs a set of Session recutils records that include each @code{ChildProcess} as a field. @item normalized Normalize the output records into record sets (@pxref{Record Sets,,, recutils, GNU recutils manual}). Normalizing into record sets allows joins across record types. The example below lists the PID of each @code{ChildProcess} and the associated PID for @code{Session} that spawned the @code{ChildProcess} where the @code{Session} was started using @command{guix build}. @example $ guix processes --format=normalized | \ recsel \ -j Session \ -t ChildProcess \ -p Session.PID,PID \ -e 'Session.ClientCommand ~ "guix build"' PID: 4435 Session_PID: 4278 PID: 4554 Session_PID: 4278 PID: 4646 Session_PID: 4278 @end example @end table @end table @node System Configuration @chapter System Configuration @cindex system configuration Guix System supports a consistent whole-system configuration mechanism. By that we mean that all aspects of the global system configuration---such as the available system services, timezone and locale settings, user accounts---are declared in a single place. Such a @dfn{system configuration} can be @dfn{instantiated}---i.e., effected. One of the advantages of putting all the system configuration under the control of Guix is that it supports transactional system upgrades, and makes it possible to roll back to a previous system instantiation, should something go wrong with the new one (@pxref{Features}). Another advantage is that it makes it easy to replicate the exact same configuration across different machines, or at different points in time, without having to resort to additional administration tools layered on top of the own tools of the system. @c Yes, we're talking of Puppet, Chef, & co. here. ↑ This section describes this mechanism. First we focus on the system administrator's viewpoint---explaining how the system is configured and instantiated. Then we show how this mechanism can be extended, for instance to support new system services. @menu * Using the Configuration System:: Customizing your GNU system. * operating-system Reference:: Detail of operating-system declarations. * File Systems:: Configuring file system mounts. * Mapped Devices:: Block device extra processing. * User Accounts:: Specifying user accounts. * Keyboard Layout:: How the system interprets key strokes. * Locales:: Language and cultural convention settings. * Services:: Specifying system services. * Setuid Programs:: Programs running with root privileges. * X.509 Certificates:: Authenticating HTTPS servers. * Name Service Switch:: Configuring libc's name service switch. * Initial RAM Disk:: Linux-Libre bootstrapping. * Bootloader Configuration:: Configuring the boot loader. * Invoking guix system:: Instantiating a system configuration. * Invoking guix deploy:: Deploying a system configuration to a remote host. * Running Guix in a VM:: How to run Guix System in a virtual machine. * Defining Services:: Adding new service definitions. @end menu @node Using the Configuration System @section Using the Configuration System The operating system is configured by providing an @code{operating-system} declaration in a file that can then be passed to the @command{guix system} command (@pxref{Invoking guix system}). A simple setup, with the default system services, the default Linux-Libre kernel, initial RAM disk, and boot loader looks like this: @findex operating-system @lisp @include os-config-bare-bones.texi @end lisp This example should be self-describing. Some of the fields defined above, such as @code{host-name} and @code{bootloader}, are mandatory. Others, such as @code{packages} and @code{services}, can be omitted, in which case they get a default value. Below we discuss the effect of some of the most important fields (@pxref{operating-system Reference}, for details about all the available fields), and how to @dfn{instantiate} the operating system using @command{guix system}. @unnumberedsubsec Bootloader @cindex legacy boot, on Intel machines @cindex BIOS boot, on Intel machines @cindex UEFI boot @cindex EFI boot The @code{bootloader} field describes the method that will be used to boot your system. Machines based on Intel processors can boot in ``legacy'' BIOS mode, as in the example above. However, more recent machines rely instead on the @dfn{Unified Extensible Firmware Interface} (UEFI) to boot. In that case, the @code{bootloader} field should contain something along these lines: @lisp (bootloader-configuration (bootloader grub-efi-bootloader) (target "/boot/efi")) @end lisp @xref{Bootloader Configuration}, for more information on the available configuration options. @unnumberedsubsec Globally-Visible Packages @vindex %base-packages The @code{packages} field lists packages that will be globally visible on the system, for all user accounts---i.e., in every user's @env{PATH} environment variable---in addition to the per-user profiles (@pxref{Invoking guix package}). The @code{%base-packages} variable provides all the tools one would expect for basic user and administrator tasks---including the GNU Core Utilities, the GNU Networking Utilities, the GNU Zile lightweight text editor, @command{find}, @command{grep}, etc. The example above adds GNU@tie{}Screen to those, taken from the @code{(gnu packages screen)} module (@pxref{Package Modules}). The @code{(list package output)} syntax can be used to add a specific output of a package: @lisp (use-modules (gnu packages)) (use-modules (gnu packages dns)) (operating-system ;; ... (packages (cons (list bind "utils") %base-packages))) @end lisp @findex specification->package Referring to packages by variable name, like @code{bind} above, has the advantage of being unambiguous; it also allows typos and such to be diagnosed right away as ``unbound variables''. The downside is that one needs to know which module defines which package, and to augment the @code{use-package-modules} line accordingly. To avoid that, one can use the @code{specification->package} procedure of the @code{(gnu packages)} module, which returns the best package for a given name or name and version: @lisp (use-modules (gnu packages)) (operating-system ;; ... (packages (append (map specification->package '("tcpdump" "htop" "gnupg@@2.0")) %base-packages))) @end lisp @unnumberedsubsec System Services @cindex services @vindex %base-services The @code{services} field lists @dfn{system services} to be made available when the system starts (@pxref{Services}). The @code{operating-system} declaration above specifies that, in addition to the basic services, we want the OpenSSH secure shell daemon listening on port 2222 (@pxref{Networking Services, @code{openssh-service-type}}). Under the hood, @code{openssh-service-type} arranges so that @command{sshd} is started with the right command-line options, possibly with supporting configuration files generated as needed (@pxref{Defining Services}). @cindex customization, of services @findex modify-services Occasionally, instead of using the base services as is, you will want to customize them. To do this, use @code{modify-services} (@pxref{Service Reference, @code{modify-services}}) to modify the list. For example, suppose you want to modify @code{guix-daemon} and Mingetty (the console log-in) in the @code{%base-services} list (@pxref{Base Services, @code{%base-services}}). To do that, you can write the following in your operating system declaration: @lisp (define %my-services ;; My very own list of services. (modify-services %base-services (guix-service-type config => (guix-configuration (inherit config) ;; Fetch substitutes from example.org. (substitute-urls (list "https://example.org/guix" "https://ci.guix.gnu.org")))) (mingetty-service-type config => (mingetty-configuration (inherit config) ;; Automatially log in as "guest". (auto-login "guest"))))) (operating-system ;; @dots{} (services %my-services)) @end lisp This changes the configuration---i.e., the service parameters---of the @code{guix-service-type} instance, and that of all the @code{mingetty-service-type} instances in the @code{%base-services} list. Observe how this is accomplished: first, we arrange for the original configuration to be bound to the identifier @code{config} in the @var{body}, and then we write the @var{body} so that it evaluates to the desired configuration. In particular, notice how we use @code{inherit} to create a new configuration which has the same values as the old configuration, but with a few modifications. @cindex encrypted disk The configuration for a typical ``desktop'' usage, with an encrypted root partition, the X11 display server, GNOME and Xfce (users can choose which of these desktop environments to use at the log-in screen by pressing @kbd{F1}), network management, power management, and more, would look like this: @lisp @include os-config-desktop.texi @end lisp A graphical system with a choice of lightweight window managers instead of full-blown desktop environments would look like this: @lisp @include os-config-lightweight-desktop.texi @end lisp This example refers to the @file{/boot/efi} file system by its UUID, @code{1234-ABCD}. Replace this UUID with the right UUID on your system, as returned by the @command{blkid} command. @xref{Desktop Services}, for the exact list of services provided by @code{%desktop-services}. @xref{X.509 Certificates}, for background information about the @code{nss-certs} package that is used here. Again, @code{%desktop-services} is just a list of service objects. If you want to remove services from there, you can do so using the procedures for list filtering (@pxref{SRFI-1 Filtering and Partitioning,,, guile, GNU Guile Reference Manual}). For instance, the following expression returns a list that contains all the services in @code{%desktop-services} minus the Avahi service: @lisp (remove (lambda (service) (eq? (service-kind service) avahi-service-type)) %desktop-services) @end lisp @unnumberedsubsec Instantiating the System Assuming the @code{operating-system} declaration is stored in the @file{my-system-config.scm} file, the @command{guix system reconfigure my-system-config.scm} command instantiates that configuration, and makes it the default GRUB boot entry (@pxref{Invoking guix system}). The normal way to change the system configuration is by updating this file and re-running @command{guix system reconfigure}. One should never have to touch files in @file{/etc} or to run commands that modify the system state such as @command{useradd} or @command{grub-install}. In fact, you must avoid that since that would not only void your warranty but also prevent you from rolling back to previous versions of your system, should you ever need to. @cindex roll-back, of the operating system Speaking of roll-back, each time you run @command{guix system reconfigure}, a new @dfn{generation} of the system is created---without modifying or deleting previous generations. Old system generations get an entry in the bootloader boot menu, allowing you to boot them in case something went wrong with the latest generation. Reassuring, no? The @command{guix system list-generations} command lists the system generations available on disk. It is also possible to roll back the system via the commands @command{guix system roll-back} and @command{guix system switch-generation}. Although the @command{guix system reconfigure} command will not modify previous generations, you must take care when the current generation is not the latest (e.g., after invoking @command{guix system roll-back}), since the operation might overwrite a later generation (@pxref{Invoking guix system}). @unnumberedsubsec The Programming Interface At the Scheme level, the bulk of an @code{operating-system} declaration is instantiated with the following monadic procedure (@pxref{The Store Monad}): @deffn {Monadic Procedure} operating-system-derivation os Return a derivation that builds @var{os}, an @code{operating-system} object (@pxref{Derivations}). The output of the derivation is a single directory that refers to all the packages, configuration files, and other supporting files needed to instantiate @var{os}. @end deffn This procedure is provided by the @code{(gnu system)} module. Along with @code{(gnu services)} (@pxref{Services}), this module contains the guts of Guix System. Make sure to visit it! @node operating-system Reference @section @code{operating-system} Reference This section summarizes all the options available in @code{operating-system} declarations (@pxref{Using the Configuration System}). @deftp {Data Type} operating-system This is the data type representing an operating system configuration. By that, we mean all the global system configuration, not per-user configuration (@pxref{Using the Configuration System}). @table @asis @item @code{kernel} (default: @code{linux-libre}) The package object of the operating system kernel to use@footnote{Currently only the Linux-libre kernel is fully supported. Using GNU@tie{}mach with the GNU@tie{}Hurd is experimental and only available when building a virtual machine disk image.}. @cindex hurd @item @code{hurd} (default: @code{#f}) The package object of the Hurd to be started by the kernel. When this field is set, produce a GNU/Hurd operating system. In that case, @code{kernel} must also be set to the @code{gnumach} package---the microkernel the Hurd runs on. @quotation Warning This feature is experimental and only supported for disk images. @end quotation @item @code{kernel-loadable-modules} (default: '()) A list of objects (usually packages) to collect loadable kernel modules from--e.g. @code{(list ddcci-driver-linux)}. @item @code{kernel-arguments} (default: @code{%default-kernel-arguments}) List of strings or gexps representing additional arguments to pass on the command-line of the kernel---e.g., @code{("console=ttyS0")}. @item @code{bootloader} The system bootloader configuration object. @xref{Bootloader Configuration}. @item @code{label} This is the label (a string) as it appears in the bootloader's menu entry. The default label includes the kernel name and version. @item @code{keyboard-layout} (default: @code{#f}) This field specifies the keyboard layout to use in the console. It can be either @code{#f}, in which case the default keyboard layout is used (usually US English), or a @code{} record. @xref{Keyboard Layout}, for more information. This keyboard layout is in effect as soon as the kernel has booted. For instance, it is the keyboard layout in effect when you type a passphrase if your root file system is on a @code{luks-device-mapping} mapped device (@pxref{Mapped Devices}). @quotation Note This does @emph{not} specify the keyboard layout used by the bootloader, nor that used by the graphical display server. @xref{Bootloader Configuration}, for information on how to specify the bootloader's keyboard layout. @xref{X Window}, for information on how to specify the keyboard layout used by the X Window System. @end quotation @item @code{initrd-modules} (default: @code{%base-initrd-modules}) @cindex initrd @cindex initial RAM disk The list of Linux kernel modules that need to be available in the initial RAM disk. @xref{Initial RAM Disk}. @item @code{initrd} (default: @code{base-initrd}) A procedure that returns an initial RAM disk for the Linux kernel. This field is provided to support low-level customization and should rarely be needed for casual use. @xref{Initial RAM Disk}. @item @code{firmware} (default: @code{%base-firmware}) @cindex firmware List of firmware packages loadable by the operating system kernel. The default includes firmware needed for Atheros- and Broadcom-based WiFi devices (Linux-libre modules @code{ath9k} and @code{b43-open}, respectively). @xref{Hardware Considerations}, for more info on supported hardware. @item @code{host-name} The host name. @item @code{hosts-file} @cindex hosts file A file-like object (@pxref{G-Expressions, file-like objects}) for use as @file{/etc/hosts} (@pxref{Host Names,,, libc, The GNU C Library Reference Manual}). The default is a file with entries for @code{localhost} and @var{host-name}. @item @code{mapped-devices} (default: @code{'()}) A list of mapped devices. @xref{Mapped Devices}. @item @code{file-systems} A list of file systems. @xref{File Systems}. @cindex swap devices @cindex swap space @item @code{swap-devices} (default: @code{'()}) A list of UUIDs, file system labels, or strings identifying devices or files to be used for ``swap space'' (@pxref{Memory Concepts,,, libc, The GNU C Library Reference Manual}). Here are some examples: @table @code @item (list (uuid "4dab5feb-d176-45de-b287-9b0a6e4c01cb")) Use the swap partition with the given UUID. You can learn the UUID of a Linux swap partition by running @command{swaplabel @var{device}}, where @var{device} is the @file{/dev} file name of that partition. @item (list (file-system-label "swap")) Use the partition with label @code{swap}. Again, the @command{swaplabel} command allows you to view and change the label of a Linux swap partition. @item (list "/swapfile") Use the file @file{/swapfile} as swap space. @item (list "/dev/sda3" "/dev/sdb2") Use the @file{/dev/sda3} and @file{/dev/sdb2} partitions as swap space. We recommend referring to swap devices by UUIDs or labels as shown above instead. @end table It is possible to specify a swap file in a file system on a mapped device (under @file{/dev/mapper}), provided that the necessary device mapping and file system are also specified. @xref{Mapped Devices} and @ref{File Systems}. @item @code{users} (default: @code{%base-user-accounts}) @itemx @code{groups} (default: @code{%base-groups}) List of user accounts and groups. @xref{User Accounts}. If the @code{users} list lacks a user account with UID@tie{}0, a ``root'' account with UID@tie{}0 is automatically added. @item @code{skeletons} (default: @code{(default-skeletons)}) A list of target file name/file-like object tuples (@pxref{G-Expressions, file-like objects}). These are the skeleton files that will be added to the home directory of newly-created user accounts. For instance, a valid value may look like this: @lisp `((".bashrc" ,(plain-file "bashrc" "echo Hello\n")) (".guile" ,(plain-file "guile" "(use-modules (ice-9 readline)) (activate-readline)"))) @end lisp @item @code{issue} (default: @code{%default-issue}) A string denoting the contents of the @file{/etc/issue} file, which is displayed when users log in on a text console. @item @code{packages} (default: @code{%base-packages}) A list of packages to be installed in the global profile, which is accessible at @file{/run/current-system/profile}. Each element is either a package variable or a package/output tuple. Here's a simple example of both: @lisp (cons* git ; the default "out" output (list git "send-email") ; another output of git %base-packages) ; the default set @end lisp The default set includes core utilities and it is good practice to install non-core utilities in user profiles (@pxref{Invoking guix package}). @item @code{timezone} A timezone identifying string---e.g., @code{"Europe/Paris"}. You can run the @command{tzselect} command to find out which timezone string corresponds to your region. Choosing an invalid timezone name causes @command{guix system} to fail. @item @code{locale} (default: @code{"en_US.utf8"}) The name of the default locale (@pxref{Locale Names,,, libc, The GNU C Library Reference Manual}). @xref{Locales}, for more information. @item @code{locale-definitions} (default: @code{%default-locale-definitions}) The list of locale definitions to be compiled and that may be used at run time. @xref{Locales}. @item @code{locale-libcs} (default: @code{(list @var{glibc})}) The list of GNU@tie{}libc packages whose locale data and tools are used to build the locale definitions. @xref{Locales}, for compatibility considerations that justify this option. @item @code{name-service-switch} (default: @code{%default-nss}) Configuration of the libc name service switch (NSS)---a @code{} object. @xref{Name Service Switch}, for details. @item @code{services} (default: @code{%base-services}) A list of service objects denoting system services. @xref{Services}. @cindex essential services @item @code{essential-services} (default: ...) The list of ``essential services''---i.e., things like instances of @code{system-service-type} and @code{host-name-service-type} (@pxref{Service Reference}), which are derived from the operating system definition itself. As a user you should @emph{never} need to touch this field. @item @code{pam-services} (default: @code{(base-pam-services)}) @cindex PAM @cindex pluggable authentication modules Linux @dfn{pluggable authentication module} (PAM) services. @c FIXME: Add xref to PAM services section. @item @code{setuid-programs} (default: @code{%setuid-programs}) List of string-valued G-expressions denoting setuid programs. @xref{Setuid Programs}. @item @code{sudoers-file} (default: @code{%sudoers-specification}) @cindex sudoers file The contents of the @file{/etc/sudoers} file as a file-like object (@pxref{G-Expressions, @code{local-file} and @code{plain-file}}). This file specifies which users can use the @command{sudo} command, what they are allowed to do, and what privileges they may gain. The default is that only @code{root} and members of the @code{wheel} group may use @code{sudo}. @end table @deffn {Scheme Syntax} this-operating-system When used in the @emph{lexical scope} of an operating system field definition, this identifier resolves to the operating system being defined. The example below shows how to refer to the operating system being defined in the definition of the @code{label} field: @lisp (use-modules (gnu) (guix)) (operating-system ;; ... (label (package-full-name (operating-system-kernel this-operating-system)))) @end lisp It is an error to refer to @code{this-operating-system} outside an operating system definition. @end deffn @end deftp @node File Systems @section File Systems The list of file systems to be mounted is specified in the @code{file-systems} field of the operating system declaration (@pxref{Using the Configuration System}). Each file system is declared using the @code{file-system} form, like this: @lisp (file-system (mount-point "/home") (device "/dev/sda3") (type "ext4")) @end lisp As usual, some of the fields are mandatory---those shown in the example above---while others can be omitted. These are described below. @deftp {Data Type} file-system Objects of this type represent file systems to be mounted. They contain the following members: @table @asis @item @code{type} This is a string specifying the type of the file system---e.g., @code{"ext4"}. @item @code{mount-point} This designates the place where the file system is to be mounted. @item @code{device} This names the ``source'' of the file system. It can be one of three things: a file system label, a file system UUID, or the name of a @file{/dev} node. Labels and UUIDs offer a way to refer to file systems without having to hard-code their actual device name@footnote{Note that, while it is tempting to use @file{/dev/disk/by-uuid} and similar device names to achieve the same result, this is not recommended: These special device nodes are created by the udev daemon and may be unavailable at the time the device is mounted.}. @findex file-system-label File system labels are created using the @code{file-system-label} procedure, UUIDs are created using @code{uuid}, and @file{/dev} node are plain strings. Here's an example of a file system referred to by its label, as shown by the @command{e2label} command: @lisp (file-system (mount-point "/home") (type "ext4") (device (file-system-label "my-home"))) @end lisp @findex uuid UUIDs are converted from their string representation (as shown by the @command{tune2fs -l} command) using the @code{uuid} form@footnote{The @code{uuid} form expects 16-byte UUIDs as defined in @uref{https://tools.ietf.org/html/rfc4122, RFC@tie{}4122}. This is the form of UUID used by the ext2 family of file systems and others, but it is different from ``UUIDs'' found in FAT file systems, for instance.}, like this: @lisp (file-system (mount-point "/home") (type "ext4") (device (uuid "4dab5feb-d176-45de-b287-9b0a6e4c01cb"))) @end lisp When the source of a file system is a mapped device (@pxref{Mapped Devices}), its @code{device} field @emph{must} refer to the mapped device name---e.g., @file{"/dev/mapper/root-partition"}. This is required so that the system knows that mounting the file system depends on having the corresponding device mapping established. @item @code{flags} (default: @code{'()}) This is a list of symbols denoting mount flags. Recognized flags include @code{read-only}, @code{bind-mount}, @code{no-dev} (disallow access to special files), @code{no-suid} (ignore setuid and setgid bits), @code{no-atime} (do not update file access times), @code{strict-atime} (update file access time), @code{lazy-time} (only update time on the in-memory version of the file inode), and @code{no-exec} (disallow program execution). @xref{Mount-Unmount-Remount,,, libc, The GNU C Library Reference Manual}, for more information on these flags. @item @code{options} (default: @code{#f}) This is either @code{#f}, or a string denoting mount options passed to the file system driver. @xref{Mount-Unmount-Remount,,, libc, The GNU C Library Reference Manual}, for details and run @command{man 8 mount} for options for various file systems. Note that the @code{file-system-options->alist} and @code{alist->file-system-options} procedures from @code{(gnu system file-systems)} can be used to convert file system options given as an association list to the string representation, and vice-versa. @item @code{mount?} (default: @code{#t}) This value indicates whether to automatically mount the file system when the system is brought up. When set to @code{#f}, the file system gets an entry in @file{/etc/fstab} (read by the @command{mount} command) but is not automatically mounted. @item @code{needed-for-boot?} (default: @code{#f}) This Boolean value indicates whether the file system is needed when booting. If that is true, then the file system is mounted when the initial RAM disk (initrd) is loaded. This is always the case, for instance, for the root file system. @item @code{check?} (default: @code{#t}) This Boolean indicates whether the file system needs to be checked for errors before being mounted. @item @code{create-mount-point?} (default: @code{#f}) When true, the mount point is created if it does not exist yet. @item @code{mount-may-fail?} (default: @code{#f}) When true, this indicates that mounting this file system can fail but that should not be considered an error. This is useful in unusual cases; an example of this is @code{efivarfs}, a file system that can only be mounted on EFI/UEFI systems. @item @code{dependencies} (default: @code{'()}) This is a list of @code{} or @code{} objects representing file systems that must be mounted or mapped devices that must be opened before (and unmounted or closed after) this one. As an example, consider a hierarchy of mounts: @file{/sys/fs/cgroup} is a dependency of @file{/sys/fs/cgroup/cpu} and @file{/sys/fs/cgroup/memory}. Another example is a file system that depends on a mapped device, for example for an encrypted partition (@pxref{Mapped Devices}). @end table @end deftp @deffn {Scheme Procedure} file-system-label @var{str} This procedure returns an opaque file system label from @var{str}, a string: @lisp (file-system-label "home") @result{} # @end lisp File system labels are used to refer to file systems by label rather than by device name. See above for examples. @end deffn The @code{(gnu system file-systems)} exports the following useful variables. @defvr {Scheme Variable} %base-file-systems These are essential file systems that are required on normal systems, such as @code{%pseudo-terminal-file-system} and @code{%immutable-store} (see below). Operating system declarations should always contain at least these. @end defvr @defvr {Scheme Variable} %pseudo-terminal-file-system This is the file system to be mounted as @file{/dev/pts}. It supports @dfn{pseudo-terminals} created @i{via} @code{openpty} and similar functions (@pxref{Pseudo-Terminals,,, libc, The GNU C Library Reference Manual}). Pseudo-terminals are used by terminal emulators such as @command{xterm}. @end defvr @defvr {Scheme Variable} %shared-memory-file-system This file system is mounted as @file{/dev/shm} and is used to support memory sharing across processes (@pxref{Memory-mapped I/O, @code{shm_open},, libc, The GNU C Library Reference Manual}). @end defvr @defvr {Scheme Variable} %immutable-store This file system performs a read-only ``bind mount'' of @file{/gnu/store}, making it read-only for all the users including @code{root}. This prevents against accidental modification by software running as @code{root} or by system administrators. The daemon itself is still able to write to the store: it remounts it read-write in its own ``name space.'' @end defvr @defvr {Scheme Variable} %binary-format-file-system The @code{binfmt_misc} file system, which allows handling of arbitrary executable file types to be delegated to user space. This requires the @code{binfmt.ko} kernel module to be loaded. @end defvr @defvr {Scheme Variable} %fuse-control-file-system The @code{fusectl} file system, which allows unprivileged users to mount and unmount user-space FUSE file systems. This requires the @code{fuse.ko} kernel module to be loaded. @end defvr The @code{(gnu system uuid)} module provides tools to deal with file system ``unique identifiers'' (UUIDs). @deffn {Scheme Procedure} uuid @var{str} [@var{type}] Return an opaque UUID (unique identifier) object of the given @var{type} (a symbol) by parsing @var{str} (a string): @lisp (uuid "4dab5feb-d176-45de-b287-9b0a6e4c01cb") @result{} #< type: dce bv: @dots{}> (uuid "1234-ABCD" 'fat) @result{} #< type: fat bv: @dots{}> @end lisp @var{type} may be one of @code{dce}, @code{iso9660}, @code{fat}, @code{ntfs}, or one of the commonly found synonyms for these. UUIDs are another way to unambiguously refer to file systems in operating system configuration. See the examples above. @end deffn @node Btrfs file system @subsection Btrfs file system The Btrfs has special features, such as subvolumes, that merit being explained in more details. The following section attempts to cover basic as well as complex uses of a Btrfs file system with the Guix System. In its simplest usage, a Btrfs file system can be described, for example, by: @lisp (file-system (mount-point "/home") (type "btrfs") (device (file-system-label "my-home"))) @end lisp The example below is more complex, as it makes use of a Btrfs subvolume, named @code{rootfs}. The parent Btrfs file system is labeled @code{my-btrfs-pool}, and is located on an encrypted device (hence the dependency on @code{mapped-devices}): @lisp (file-system (device (file-system-label "my-btrfs-pool")) (mount-point "/") (type "btrfs") (options "subvol=rootfs") (dependencies mapped-devices)) @end lisp Some bootloaders, for example GRUB, only mount a Btrfs partition at its top level during the early boot, and rely on their configuration to refer to the correct subvolume path within that top level. The bootloaders operating in this way typically produce their configuration on a running system where the Btrfs partitions are already mounted and where the subvolume information is readily available. As an example, @command{grub-mkconfig}, the configuration generator command shipped with GRUB, reads @file{/proc/self/mountinfo} to determine the top-level path of a subvolume. The Guix System produces a bootloader configuration using the operating system configuration as its sole input; it is therefore necessary to extract the subvolume name on which @file{/gnu/store} lives (if any) from that operating system configuration. To better illustrate, consider a subvolume named 'rootfs' which contains the root file system data. In such situation, the GRUB bootloader would only see the top level of the root Btrfs partition, e.g.: @example / (top level) ├── rootfs (subvolume directory) ├── gnu (normal directory) ├── store (normal directory) [...] @end example Thus, the subvolume name must be prepended to the @file{/gnu/store} path of the kernel, initrd binaries and any other files referred to in the GRUB configuration that must be found during the early boot. The next example shows a nested hierarchy of subvolumes and directories: @example / (top level) ├── rootfs (subvolume) ├── gnu (normal directory) ├── store (subvolume) [...] @end example This scenario would work without mounting the 'store' subvolume. Mounting 'rootfs' is sufficient, since the subvolume name matches its intended mount point in the file system hierarchy. Alternatively, the 'store' subvolume could be referred to by setting the @code{subvol} option to either @code{/rootfs/gnu/store} or @code{rootfs/gnu/store}. Finally, a more contrived example of nested subvolumes: @example / (top level) ├── root-snapshots (subvolume) ├── root-current (subvolume) ├── guix-store (subvolume) [...] @end example Here, the 'guix-store' subvolume doesn't match its intended mount point, so it is necessary to mount it. The subvolume must be fully specified, by passing its file name to the @code{subvol} option. To illustrate, the 'guix-store' subvolume could be mounted on @file{/gnu/store} by using a file system declaration such as: @lisp (file-system (device (file-system-label "btrfs-pool-1")) (mount-point "/gnu/store") (type "btrfs") (options "subvol=root-snapshots/root-current/guix-store,\ compress-force=zstd,space_cache=v2")) @end lisp @node Mapped Devices @section Mapped Devices @cindex device mapping @cindex mapped devices The Linux kernel has a notion of @dfn{device mapping}: a block device, such as a hard disk partition, can be @dfn{mapped} into another device, usually in @code{/dev/mapper/}, with additional processing over the data that flows through it@footnote{Note that the GNU@tie{}Hurd makes no difference between the concept of a ``mapped device'' and that of a file system: both boil down to @emph{translating} input/output operations made on a file to operations on its backing store. Thus, the Hurd implements mapped devices, like file systems, using the generic @dfn{translator} mechanism (@pxref{Translators,,, hurd, The GNU Hurd Reference Manual}).}. A typical example is encryption device mapping: all writes to the mapped device are encrypted, and all reads are deciphered, transparently. Guix extends this notion by considering any device or set of devices that are @dfn{transformed} in some way to create a new device; for instance, RAID devices are obtained by @dfn{assembling} several other devices, such as hard disks or partitions, into a new one that behaves as one partition. Mapped devices are declared using the @code{mapped-device} form, defined as follows; for examples, see below. @deftp {Data Type} mapped-device Objects of this type represent device mappings that will be made when the system boots up. @table @code @item source This is either a string specifying the name of the block device to be mapped, such as @code{"/dev/sda3"}, or a list of such strings when several devices need to be assembled for creating a new one. In case of LVM this is a string specifying name of the volume group to be mapped. @item target This string specifies the name of the resulting mapped device. For kernel mappers such as encrypted devices of type @code{luks-device-mapping}, specifying @code{"my-partition"} leads to the creation of the @code{"/dev/mapper/my-partition"} device. For RAID devices of type @code{raid-device-mapping}, the full device name such as @code{"/dev/md0"} needs to be given. LVM logical volumes of type @code{lvm-device-mapping} need to be specified as @code{"VGNAME-LVNAME"}. @item targets This list of strings specifies names of the resulting mapped devices in case there are several. The format is identical to @var{target}. @item type This must be a @code{mapped-device-kind} object, which specifies how @var{source} is mapped to @var{target}. @end table @end deftp @defvr {Scheme Variable} luks-device-mapping This defines LUKS block device encryption using the @command{cryptsetup} command from the package with the same name. It relies on the @code{dm-crypt} Linux kernel module. @end defvr @defvr {Scheme Variable} raid-device-mapping This defines a RAID device, which is assembled using the @code{mdadm} command from the package with the same name. It requires a Linux kernel module for the appropriate RAID level to be loaded, such as @code{raid456} for RAID-4, RAID-5 or RAID-6, or @code{raid10} for RAID-10. @end defvr @cindex LVM, logical volume manager @defvr {Scheme Variable} lvm-device-mapping This defines one or more logical volumes for the Linux @uref{https://www.sourceware.org/lvm2/, Logical Volume Manager (LVM)}. The volume group is activated by the @command{vgchange} command from the @code{lvm2} package. @end defvr @cindex disk encryption @cindex LUKS The following example specifies a mapping from @file{/dev/sda3} to @file{/dev/mapper/home} using LUKS---the @url{https://gitlab.com/cryptsetup/cryptsetup,Linux Unified Key Setup}, a standard mechanism for disk encryption. The @file{/dev/mapper/home} device can then be used as the @code{device} of a @code{file-system} declaration (@pxref{File Systems}). @lisp (mapped-device (source "/dev/sda3") (target "home") (type luks-device-mapping)) @end lisp Alternatively, to become independent of device numbering, one may obtain the LUKS UUID (@dfn{unique identifier}) of the source device by a command like: @example cryptsetup luksUUID /dev/sda3 @end example and use it as follows: @lisp (mapped-device (source (uuid "cb67fc72-0d54-4c88-9d4b-b225f30b0f44")) (target "home") (type luks-device-mapping)) @end lisp @cindex swap encryption It is also desirable to encrypt swap space, since swap space may contain sensitive data. One way to accomplish that is to use a swap file in a file system on a device mapped via LUKS encryption. In this way, the swap file is encrypted because the entire device is encrypted. @xref{Preparing for Installation,,Disk Partitioning}, for an example. A RAID device formed of the partitions @file{/dev/sda1} and @file{/dev/sdb1} may be declared as follows: @lisp (mapped-device (source (list "/dev/sda1" "/dev/sdb1")) (target "/dev/md0") (type raid-device-mapping)) @end lisp The @file{/dev/md0} device can then be used as the @code{device} of a @code{file-system} declaration (@pxref{File Systems}). Note that the RAID level need not be given; it is chosen during the initial creation and formatting of the RAID device and is determined automatically later. LVM logical volumes ``alpha'' and ``beta'' from volume group ``vg0'' can be declared as follows: @lisp (mapped-device (source "vg0") (target (list "vg0-alpha" "vg0-beta")) (type lvm-device-mapping)) @end lisp Devices @file{/dev/mapper/vg0-alpha} and @file{/dev/mapper/vg0-beta} can then be used as the @code{device} of a @code{file-system} declaration (@pxref{File Systems}). @node User Accounts @section User Accounts @cindex users @cindex accounts @cindex user accounts User accounts and groups are entirely managed through the @code{operating-system} declaration. They are specified with the @code{user-account} and @code{user-group} forms: @lisp (user-account (name "alice") (group "users") (supplementary-groups '("wheel" ;allow use of sudo, etc. "audio" ;sound card "video" ;video devices such as webcams "cdrom")) ;the good ol' CD-ROM (comment "Bob's sister")) @end lisp Here's a user account that uses a different shell and a custom home directory (the default would be @file{"/home/bob"}): @lisp (user-account (name "bob") (group "users") (comment "Alice's bro") (shell (file-append zsh "/bin/zsh")) (home-directory "/home/robert")) @end lisp When booting or upon completion of @command{guix system reconfigure}, the system ensures that only the user accounts and groups specified in the @code{operating-system} declaration exist, and with the specified properties. Thus, account or group creations or modifications made by directly invoking commands such as @command{useradd} are lost upon reconfiguration or reboot. This ensures that the system remains exactly as declared. @deftp {Data Type} user-account Objects of this type represent user accounts. The following members may be specified: @table @asis @item @code{name} The name of the user account. @item @code{group} @cindex groups This is the name (a string) or identifier (a number) of the user group this account belongs to. @item @code{supplementary-groups} (default: @code{'()}) Optionally, this can be defined as a list of group names that this account belongs to. @item @code{uid} (default: @code{#f}) This is the user ID for this account (a number), or @code{#f}. In the latter case, a number is automatically chosen by the system when the account is created. @item @code{comment} (default: @code{""}) A comment about the account, such as the account owner's full name. @item @code{home-directory} This is the name of the home directory for the account. @item @code{create-home-directory?} (default: @code{#t}) Indicates whether the home directory of this account should be created if it does not exist yet. @item @code{shell} (default: Bash) This is a G-expression denoting the file name of a program to be used as the shell (@pxref{G-Expressions}). For example, you would refer to the Bash executable like this: @lisp (file-append bash "/bin/bash") @end lisp @noindent ... and to the Zsh executable like that: @lisp (file-append zsh "/bin/zsh") @end lisp @item @code{system?} (default: @code{#f}) This Boolean value indicates whether the account is a ``system'' account. System accounts are sometimes treated specially; for instance, graphical login managers do not list them. @anchor{user-account-password} @cindex password, for user accounts @item @code{password} (default: @code{#f}) You would normally leave this field to @code{#f}, initialize user passwords as @code{root} with the @command{passwd} command, and then let users change it with @command{passwd}. Passwords set with @command{passwd} are of course preserved across reboot and reconfiguration. If you @emph{do} want to set an initial password for an account, then this field must contain the encrypted password, as a string. You can use the @code{crypt} procedure for this purpose: @lisp (user-account (name "charlie") (group "users") ;; Specify a SHA-512-hashed initial password. (password (crypt "InitialPassword!" "$6$abc"))) @end lisp @quotation Note The hash of this initial password will be available in a file in @file{/gnu/store}, readable by all the users, so this method must be used with care. @end quotation @xref{Passphrase Storage,,, libc, The GNU C Library Reference Manual}, for more information on password encryption, and @ref{Encryption,,, guile, GNU Guile Reference Manual}, for information on Guile's @code{crypt} procedure. @end table @end deftp @cindex groups User group declarations are even simpler: @lisp (user-group (name "students")) @end lisp @deftp {Data Type} user-group This type is for, well, user groups. There are just a few fields: @table @asis @item @code{name} The name of the group. @item @code{id} (default: @code{#f}) The group identifier (a number). If @code{#f}, a new number is automatically allocated when the group is created. @item @code{system?} (default: @code{#f}) This Boolean value indicates whether the group is a ``system'' group. System groups have low numerical IDs. @item @code{password} (default: @code{#f}) What, user groups can have a password? Well, apparently yes. Unless @code{#f}, this field specifies the password of the group. @end table @end deftp For convenience, a variable lists all the basic user groups one may expect: @defvr {Scheme Variable} %base-groups This is the list of basic user groups that users and/or packages expect to be present on the system. This includes groups such as ``root'', ``wheel'', and ``users'', as well as groups used to control access to specific devices such as ``audio'', ``disk'', and ``cdrom''. @end defvr @defvr {Scheme Variable} %base-user-accounts This is the list of basic system accounts that programs may expect to find on a GNU/Linux system, such as the ``nobody'' account. Note that the ``root'' account is not included here. It is a special-case and is automatically added whether or not it is specified. @end defvr @node Keyboard Layout @section Keyboard Layout @cindex keyboard layout @cindex keymap To specify what each key of your keyboard does, you need to tell the operating system what @dfn{keyboard layout} you want to use. The default, when nothing is specified, is the US English QWERTY layout for 105-key PC keyboards. However, German speakers will usually prefer the German QWERTZ layout, French speakers will want the AZERTY layout, and so on; hackers might prefer Dvorak or bépo, and they might even want to further customize the effect of some of the keys. This section explains how to get that done. @cindex keyboard layout, definition There are three components that will want to know about your keyboard layout: @itemize @item The @emph{bootloader} may want to know what keyboard layout you want to use (@pxref{Bootloader Configuration, @code{keyboard-layout}}). This is useful if you want, for instance, to make sure that you can type the passphrase of your encrypted root partition using the right layout. @item The @emph{operating system kernel}, Linux, will need that so that the console is properly configured (@pxref{operating-system Reference, @code{keyboard-layout}}). @item The @emph{graphical display server}, usually Xorg, also has its own idea of the keyboard layout (@pxref{X Window, @code{keyboard-layout}}). @end itemize Guix allows you to configure all three separately but, fortunately, it allows you to share the same keyboard layout for all three components. @cindex XKB, keyboard layouts Keyboard layouts are represented by records created by the @code{keyboard-layout} procedure of @code{(gnu system keyboard)}. Following the X Keyboard extension (XKB), each layout has four attributes: a name (often a language code such as ``fi'' for Finnish or ``jp'' for Japanese), an optional variant name, an optional keyboard model name, and a possibly empty list of additional options. In most cases the layout name is all you care about. @deffn {Scheme Procedure} keyboard-layout @var{name} [@var{variant}] @ [#:model] [#:options '()] Return a new keyboard layout with the given @var{name} and @var{variant}. @var{name} must be a string such as @code{"fr"}; @var{variant} must be a string such as @code{"bepo"} or @code{"nodeadkeys"}. See the @code{xkeyboard-config} package for valid options. @end deffn Here are a few examples: @lisp ;; The German QWERTZ layout. Here we assume a standard ;; "pc105" keyboard model. (keyboard-layout "de") ;; The bépo variant of the French layout. (keyboard-layout "fr" "bepo") ;; The Catalan layout. (keyboard-layout "es" "cat") ;; Arabic layout with "Alt-Shift" to switch to US layout. (keyboard-layout "ar,us" #:options '("grp:alt_shift_toggle")) ;; The Latin American Spanish layout. In addition, the ;; "Caps Lock" key is used as an additional "Ctrl" key, ;; and the "Menu" key is used as a "Compose" key to enter ;; accented letters. (keyboard-layout "latam" #:options '("ctrl:nocaps" "compose:menu")) ;; The Russian layout for a ThinkPad keyboard. (keyboard-layout "ru" #:model "thinkpad") ;; The "US international" layout, which is the US layout plus ;; dead keys to enter accented characters. This is for an ;; Apple MacBook keyboard. (keyboard-layout "us" "intl" #:model "macbook78") @end lisp See the @file{share/X11/xkb} directory of the @code{xkeyboard-config} package for a complete list of supported layouts, variants, and models. @cindex keyboard layout, configuration Let's say you want your system to use the Turkish keyboard layout throughout your system---bootloader, console, and Xorg. Here's what your system configuration would look like: @findex set-xorg-configuration @lisp ;; Using the Turkish layout for the bootloader, the console, ;; and for Xorg. (operating-system ;; ... (keyboard-layout (keyboard-layout "tr")) ;for the console (bootloader (bootloader-configuration (bootloader grub-efi-bootloader) (target "/boot/efi") (keyboard-layout keyboard-layout))) ;for GRUB (services (cons (set-xorg-configuration (xorg-configuration ;for Xorg (keyboard-layout keyboard-layout))) %desktop-services))) @end lisp In the example above, for GRUB and for Xorg, we just refer to the @code{keyboard-layout} field defined above, but we could just as well refer to a different layout. The @code{set-xorg-configuration} procedure communicates the desired Xorg configuration to the graphical log-in manager, by default GDM. We've discussed how to specify the @emph{default} keyboard layout of your system when it starts, but you can also adjust it at run time: @itemize @item If you're using GNOME, its settings panel has a ``Region & Language'' entry where you can select one or more keyboard layouts. @item Under Xorg, the @command{setxkbmap} command (from the same-named package) allows you to change the current layout. For example, this is how you would change the layout to US Dvorak: @example setxkbmap us dvorak @end example @item The @code{loadkeys} command changes the keyboard layout in effect in the Linux console. However, note that @code{loadkeys} does @emph{not} use the XKB keyboard layout categorization described above. The command below loads the French bépo layout: @example loadkeys fr-bepo @end example @end itemize @node Locales @section Locales @cindex locale A @dfn{locale} defines cultural conventions for a particular language and region of the world (@pxref{Locales,,, libc, The GNU C Library Reference Manual}). Each locale has a name that typically has the form @code{@var{language}_@var{territory}.@var{codeset}}---e.g., @code{fr_LU.utf8} designates the locale for the French language, with cultural conventions from Luxembourg, and using the UTF-8 encoding. @cindex locale definition Usually, you will want to specify the default locale for the machine using the @code{locale} field of the @code{operating-system} declaration (@pxref{operating-system Reference, @code{locale}}). The selected locale is automatically added to the @dfn{locale definitions} known to the system if needed, with its codeset inferred from its name---e.g., @code{bo_CN.utf8} will be assumed to use the @code{UTF-8} codeset. Additional locale definitions can be specified in the @code{locale-definitions} slot of @code{operating-system}---this is useful, for instance, if the codeset could not be inferred from the locale name. The default set of locale definitions includes some widely used locales, but not all the available locales, in order to save space. For instance, to add the North Frisian locale for Germany, the value of that field may be: @lisp (cons (locale-definition (name "fy_DE.utf8") (source "fy_DE")) %default-locale-definitions) @end lisp Likewise, to save space, one might want @code{locale-definitions} to list only the locales that are actually used, as in: @lisp (list (locale-definition (name "ja_JP.eucjp") (source "ja_JP") (charset "EUC-JP"))) @end lisp @vindex LOCPATH The compiled locale definitions are available at @file{/run/current-system/locale/X.Y}, where @code{X.Y} is the libc version, which is the default location where the GNU@tie{}libc provided by Guix looks for locale data. This can be overridden using the @env{LOCPATH} environment variable (@pxref{locales-and-locpath, @env{LOCPATH} and locale packages}). The @code{locale-definition} form is provided by the @code{(gnu system locale)} module. Details are given below. @deftp {Data Type} locale-definition This is the data type of a locale definition. @table @asis @item @code{name} The name of the locale. @xref{Locale Names,,, libc, The GNU C Library Reference Manual}, for more information on locale names. @item @code{source} The name of the source for that locale. This is typically the @code{@var{language}_@var{territory}} part of the locale name. @item @code{charset} (default: @code{"UTF-8"}) The ``character set'' or ``code set'' for that locale, @uref{https://www.iana.org/assignments/character-sets, as defined by IANA}. @end table @end deftp @defvr {Scheme Variable} %default-locale-definitions A list of commonly used UTF-8 locales, used as the default value of the @code{locale-definitions} field of @code{operating-system} declarations. @cindex locale name @cindex normalized codeset in locale names These locale definitions use the @dfn{normalized codeset} for the part that follows the dot in the name (@pxref{Using gettextized software, normalized codeset,, libc, The GNU C Library Reference Manual}). So for instance it has @code{uk_UA.utf8} but @emph{not}, say, @code{uk_UA.UTF-8}. @end defvr @subsection Locale Data Compatibility Considerations @cindex incompatibility, of locale data @code{operating-system} declarations provide a @code{locale-libcs} field to specify the GNU@tie{}libc packages that are used to compile locale declarations (@pxref{operating-system Reference}). ``Why would I care?'', you may ask. Well, it turns out that the binary format of locale data is occasionally incompatible from one libc version to another. @c See @c and . For instance, a program linked against libc version 2.21 is unable to read locale data produced with libc 2.22; worse, that program @emph{aborts} instead of simply ignoring the incompatible locale data@footnote{Versions 2.23 and later of GNU@tie{}libc will simply skip the incompatible locale data, which is already an improvement.}. Similarly, a program linked against libc 2.22 can read most, but not all, of the locale data from libc 2.21 (specifically, @env{LC_COLLATE} data is incompatible); thus calls to @code{setlocale} may fail, but programs will not abort. The ``problem'' with Guix is that users have a lot of freedom: They can choose whether and when to upgrade software in their profiles, and might be using a libc version different from the one the system administrator used to build the system-wide locale data. Fortunately, unprivileged users can also install their own locale data and define @env{GUIX_LOCPATH} accordingly (@pxref{locales-and-locpath, @env{GUIX_LOCPATH} and locale packages}). Still, it is best if the system-wide locale data at @file{/run/current-system/locale} is built for all the libc versions actually in use on the system, so that all the programs can access it---this is especially crucial on a multi-user system. To do that, the administrator can specify several libc packages in the @code{locale-libcs} field of @code{operating-system}: @lisp (use-package-modules base) (operating-system ;; @dots{} (locale-libcs (list glibc-2.21 (canonical-package glibc)))) @end lisp This example would lead to a system containing locale definitions for both libc 2.21 and the current version of libc in @file{/run/current-system/locale}. @node Services @section Services @cindex system services An important part of preparing an @code{operating-system} declaration is listing @dfn{system services} and their configuration (@pxref{Using the Configuration System}). System services are typically daemons launched when the system boots, or other actions needed at that time---e.g., configuring network access. Guix has a broad definition of ``service'' (@pxref{Service Composition}), but many services are managed by the GNU@tie{}Shepherd (@pxref{Shepherd Services}). On a running system, the @command{herd} command allows you to list the available services, show their status, start and stop them, or do other specific operations (@pxref{Jump Start,,, shepherd, The GNU Shepherd Manual}). For example: @example # herd status @end example The above command, run as @code{root}, lists the currently defined services. The @command{herd doc} command shows a synopsis of the given service and its associated actions: @example # herd doc nscd Run libc's name service cache daemon (nscd). # herd doc nscd action invalidate invalidate: Invalidate the given cache--e.g., 'hosts' for host name lookups. @end example The @command{start}, @command{stop}, and @command{restart} sub-commands have the effect you would expect. For instance, the commands below stop the nscd service and restart the Xorg display server: @example # herd stop nscd Service nscd has been stopped. # herd restart xorg-server Service xorg-server has been stopped. Service xorg-server has been started. @end example The following sections document the available services, starting with the core services, that may be used in an @code{operating-system} declaration. @menu * Base Services:: Essential system services. * Scheduled Job Execution:: The mcron service. * Log Rotation:: The rottlog service. * Networking Services:: Network setup, SSH daemon, etc. * Unattended Upgrades:: Automated system upgrades. * X Window:: Graphical display. * Printing Services:: Local and remote printer support. * Desktop Services:: D-Bus and desktop services. * Sound Services:: ALSA and Pulseaudio services. * Database Services:: SQL databases, key-value stores, etc. * Mail Services:: IMAP, POP3, SMTP, and all that. * Messaging Services:: Messaging services. * Telephony Services:: Telephony services. * Monitoring Services:: Monitoring services. * Kerberos Services:: Kerberos services. * LDAP Services:: LDAP services. * Web Services:: Web servers. * Certificate Services:: TLS certificates via Let's Encrypt. * DNS Services:: DNS daemons. * VPN Services:: VPN daemons. * Network File System:: NFS related services. * Continuous Integration:: The Cuirass service. * Power Management Services:: Extending battery life. * Audio Services:: The MPD. * Virtualization Services:: Virtualization services. * Version Control Services:: Providing remote access to Git repositories. * Game Services:: Game servers. * PAM Mount Service:: Service to mount volumes when logging in. * Guix Services:: Services relating specifically to Guix. * Linux Services:: Services tied to the Linux kernel. * Hurd Services:: Services specific for a Hurd System. * Miscellaneous Services:: Other services. @end menu @node Base Services @subsection Base Services The @code{(gnu services base)} module provides definitions for the basic services that one expects from the system. The services exported by this module are listed below. @defvr {Scheme Variable} %base-services This variable contains a list of basic services (@pxref{Service Types and Services}, for more information on service objects) one would expect from the system: a login service (mingetty) on each tty, syslogd, the libc name service cache daemon (nscd), the udev device manager, and more. This is the default value of the @code{services} field of @code{operating-system} declarations. Usually, when customizing a system, you will want to append services to @code{%base-services}, like this: @lisp (append (list (service avahi-service-type) (service openssh-service-type)) %base-services) @end lisp @end defvr @defvr {Scheme Variable} special-files-service-type This is the service that sets up ``special files'' such as @file{/bin/sh}; an instance of it is part of @code{%base-services}. The value associated with @code{special-files-service-type} services must be a list of tuples where the first element is the ``special file'' and the second element is its target. By default it is: @cindex @file{/bin/sh} @cindex @file{sh}, in @file{/bin} @lisp `(("/bin/sh" ,(file-append bash "/bin/sh"))) @end lisp @cindex @file{/usr/bin/env} @cindex @file{env}, in @file{/usr/bin} If you want to add, say, @code{/usr/bin/env} to your system, you can change it to: @lisp `(("/bin/sh" ,(file-append bash "/bin/sh")) ("/usr/bin/env" ,(file-append coreutils "/bin/env"))) @end lisp Since this is part of @code{%base-services}, you can use @code{modify-services} to customize the set of special files (@pxref{Service Reference, @code{modify-services}}). But the simple way to add a special file is @i{via} the @code{extra-special-file} procedure (see below). @end defvr @deffn {Scheme Procedure} extra-special-file @var{file} @var{target} Use @var{target} as the ``special file'' @var{file}. For example, adding the following lines to the @code{services} field of your operating system declaration leads to a @file{/usr/bin/env} symlink: @lisp (extra-special-file "/usr/bin/env" (file-append coreutils "/bin/env")) @end lisp @end deffn @deffn {Scheme Procedure} host-name-service @var{name} Return a service that sets the host name to @var{name}. @end deffn @defvr {Scheme Variable} console-font-service-type Install the given fonts on the specified ttys (fonts are per virtual console on the kernel Linux). The value of this service is a list of tty/font pairs. The font can be the name of a font provided by the @code{kbd} package or any valid argument to @command{setfont}, as in this example: @lisp `(("tty1" . "LatGrkCyr-8x16") ("tty2" . ,(file-append font-tamzen "/share/kbd/consolefonts/TamzenForPowerline10x20.psf")) ("tty3" . ,(file-append font-terminus "/share/consolefonts/ter-132n"))) ; for HDPI @end lisp @end defvr @deffn {Scheme Procedure} login-service @var{config} Return a service to run login according to @var{config}, a @code{} object, which specifies the message of the day, among other things. @end deffn @deftp {Data Type} login-configuration This is the data type representing the configuration of login. @table @asis @item @code{motd} @cindex message of the day A file-like object containing the ``message of the day''. @item @code{allow-empty-passwords?} (default: @code{#t}) Allow empty passwords by default so that first-time users can log in when the 'root' account has just been created. @end table @end deftp @deffn {Scheme Procedure} mingetty-service @var{config} Return a service to run mingetty according to @var{config}, a @code{} object, which specifies the tty to run, among other things. @end deffn @deftp {Data Type} mingetty-configuration This is the data type representing the configuration of Mingetty, which provides the default implementation of virtual console log-in. @table @asis @item @code{tty} The name of the console this Mingetty runs on---e.g., @code{"tty1"}. @item @code{auto-login} (default: @code{#f}) When true, this field must be a string denoting the user name under which the system automatically logs in. When it is @code{#f}, a user name and password must be entered to log in. @item @code{login-program} (default: @code{#f}) This must be either @code{#f}, in which case the default log-in program is used (@command{login} from the Shadow tool suite), or a gexp denoting the name of the log-in program. @item @code{login-pause?} (default: @code{#f}) When set to @code{#t} in conjunction with @var{auto-login}, the user will have to press a key before the log-in shell is launched. @item @code{clear-on-logout?} (default: @code{#t}) When set to @code{#t}, the screen will be cleared after logout. @item @code{mingetty} (default: @var{mingetty}) The Mingetty package to use. @end table @end deftp @deffn {Scheme Procedure} agetty-service @var{config} Return a service to run agetty according to @var{config}, an @code{} object, which specifies the tty to run, among other things. @end deffn @deftp {Data Type} agetty-configuration This is the data type representing the configuration of agetty, which implements virtual and serial console log-in. See the @code{agetty(8)} man page for more information. @table @asis @item @code{tty} The name of the console this agetty runs on, as a string---e.g., @code{"ttyS0"}. This argument is optional, it will default to a reasonable default serial port used by the kernel Linux. For this, if there is a value for an option @code{agetty.tty} in the kernel command line, agetty will extract the device name of the serial port from it and use that. If not and if there is a value for an option @code{console} with a tty in the Linux command line, agetty will extract the device name of the serial port from it and use that. In both cases, agetty will leave the other serial device settings (baud rate etc.)@: alone---in the hope that Linux pinned them to the correct values. @item @code{baud-rate} (default: @code{#f}) A string containing a comma-separated list of one or more baud rates, in descending order. @item @code{term} (default: @code{#f}) A string containing the value used for the @env{TERM} environment variable. @item @code{eight-bits?} (default: @code{#f}) When @code{#t}, the tty is assumed to be 8-bit clean, and parity detection is disabled. @item @code{auto-login} (default: @code{#f}) When passed a login name, as a string, the specified user will be logged in automatically without prompting for their login name or password. @item @code{no-reset?} (default: @code{#f}) When @code{#t}, don't reset terminal cflags (control modes). @item @code{host} (default: @code{#f}) This accepts a string containing the ``login_host'', which will be written into the @file{/var/run/utmpx} file. @item @code{remote?} (default: @code{#f}) When set to @code{#t} in conjunction with @var{host}, this will add an @code{-r} fakehost option to the command line of the login program specified in @var{login-program}. @item @code{flow-control?} (default: @code{#f}) When set to @code{#t}, enable hardware (RTS/CTS) flow control. @item @code{no-issue?} (default: @code{#f}) When set to @code{#t}, the contents of the @file{/etc/issue} file will not be displayed before presenting the login prompt. @item @code{init-string} (default: @code{#f}) This accepts a string that will be sent to the tty or modem before sending anything else. It can be used to initialize a modem. @item @code{no-clear?} (default: @code{#f}) When set to @code{#t}, agetty will not clear the screen before showing the login prompt. @item @code{login-program} (default: (file-append shadow "/bin/login")) This must be either a gexp denoting the name of a log-in program, or unset, in which case the default value is the @command{login} from the Shadow tool suite. @item @code{local-line} (default: @code{#f}) Control the CLOCAL line flag. This accepts one of three symbols as arguments, @code{'auto}, @code{'always}, or @code{'never}. If @code{#f}, the default value chosen by agetty is @code{'auto}. @item @code{extract-baud?} (default: @code{#f}) When set to @code{#t}, instruct agetty to try to extract the baud rate from the status messages produced by certain types of modems. @item @code{skip-login?} (default: @code{#f}) When set to @code{#t}, do not prompt the user for a login name. This can be used with @var{login-program} field to use non-standard login systems. @item @code{no-newline?} (default: @code{#f}) When set to @code{#t}, do not print a newline before printing the @file{/etc/issue} file. @c Is this dangerous only when used with login-program, or always? @item @code{login-options} (default: @code{#f}) This option accepts a string containing options that are passed to the login program. When used with the @var{login-program}, be aware that a malicious user could try to enter a login name containing embedded options that could be parsed by the login program. @item @code{login-pause} (default: @code{#f}) When set to @code{#t}, wait for any key before showing the login prompt. This can be used in conjunction with @var{auto-login} to save memory by lazily spawning shells. @item @code{chroot} (default: @code{#f}) Change root to the specified directory. This option accepts a directory path as a string. @item @code{hangup?} (default: @code{#f}) Use the Linux system call @code{vhangup} to do a virtual hangup of the specified terminal. @item @code{keep-baud?} (default: @code{#f}) When set to @code{#t}, try to keep the existing baud rate. The baud rates from @var{baud-rate} are used when agetty receives a @key{BREAK} character. @item @code{timeout} (default: @code{#f}) When set to an integer value, terminate if no user name could be read within @var{timeout} seconds. @item @code{detect-case?} (default: @code{#f}) When set to @code{#t}, turn on support for detecting an uppercase-only terminal. This setting will detect a login name containing only uppercase letters as indicating an uppercase-only terminal and turn on some upper-to-lower case conversions. Note that this will not support Unicode characters. @item @code{wait-cr?} (default: @code{#f}) When set to @code{#t}, wait for the user or modem to send a carriage-return or linefeed character before displaying @file{/etc/issue} or login prompt. This is typically used with the @var{init-string} option. @item @code{no-hints?} (default: @code{#f}) When set to @code{#t}, do not print hints about Num, Caps, and Scroll locks. @item @code{no-hostname?} (default: @code{#f}) By default, the hostname is printed. When this option is set to @code{#t}, no hostname will be shown at all. @item @code{long-hostname?} (default: @code{#f}) By default, the hostname is only printed until the first dot. When this option is set to @code{#t}, the fully qualified hostname by @code{gethostname} or @code{getaddrinfo} is shown. @item @code{erase-characters} (default: @code{#f}) This option accepts a string of additional characters that should be interpreted as backspace when the user types their login name. @item @code{kill-characters} (default: @code{#f}) This option accepts a string that should be interpreted to mean ``ignore all previous characters'' (also called a ``kill'' character) when the user types their login name. @item @code{chdir} (default: @code{#f}) This option accepts, as a string, a directory path that will be changed to before login. @item @code{delay} (default: @code{#f}) This options accepts, as an integer, the number of seconds to sleep before opening the tty and displaying the login prompt. @item @code{nice} (default: @code{#f}) This option accepts, as an integer, the nice value with which to run the @command{login} program. @item @code{extra-options} (default: @code{'()}) This option provides an ``escape hatch'' for the user to provide arbitrary command-line arguments to @command{agetty} as a list of strings. @end table @end deftp @deffn {Scheme Procedure} kmscon-service-type @var{config} Return a service to run @uref{https://www.freedesktop.org/wiki/Software/kmscon,kmscon} according to @var{config}, a @code{} object, which specifies the tty to run, among other things. @end deffn @deftp {Data Type} kmscon-configuration This is the data type representing the configuration of Kmscon, which implements virtual console log-in. @table @asis @item @code{virtual-terminal} The name of the console this Kmscon runs on---e.g., @code{"tty1"}. @item @code{login-program} (default: @code{#~(string-append #$shadow "/bin/login")}) A gexp denoting the name of the log-in program. The default log-in program is @command{login} from the Shadow tool suite. @item @code{login-arguments} (default: @code{'("-p")}) A list of arguments to pass to @command{login}. @item @code{auto-login} (default: @code{#f}) When passed a login name, as a string, the specified user will be logged in automatically without prompting for their login name or password. @item @code{hardware-acceleration?} (default: #f) Whether to use hardware acceleration. @item @code{kmscon} (default: @var{kmscon}) The Kmscon package to use. @end table @end deftp @cindex name service cache daemon @cindex nscd @deffn {Scheme Procedure} nscd-service [@var{config}] [#:glibc glibc] @ [#:name-services '()] Return a service that runs the libc name service cache daemon (nscd) with the given @var{config}---an @code{} object. @xref{Name Service Switch}, for an example. For convenience, the Shepherd service for nscd provides the following actions: @table @code @item invalidate @cindex cache invalidation, nscd @cindex nscd, cache invalidation This invalidate the given cache. For instance, running: @example herd invalidate nscd hosts @end example @noindent invalidates the host name lookup cache of nscd. @item statistics Running @command{herd statistics nscd} displays information about nscd usage and caches. @end table @end deffn @defvr {Scheme Variable} %nscd-default-configuration This is the default @code{} value (see below) used by @code{nscd-service}. It uses the caches defined by @code{%nscd-default-caches}; see below. @end defvr @deftp {Data Type} nscd-configuration This is the data type representing the name service cache daemon (nscd) configuration. @table @asis @item @code{name-services} (default: @code{'()}) List of packages denoting @dfn{name services} that must be visible to the nscd---e.g., @code{(list @var{nss-mdns})}. @item @code{glibc} (default: @var{glibc}) Package object denoting the GNU C Library providing the @command{nscd} command. @item @code{log-file} (default: @code{"/var/log/nscd.log"}) Name of the nscd log file. This is where debugging output goes when @code{debug-level} is strictly positive. @item @code{debug-level} (default: @code{0}) Integer denoting the debugging levels. Higher numbers mean that more debugging output is logged. @item @code{caches} (default: @code{%nscd-default-caches}) List of @code{} objects denoting things to be cached; see below. @end table @end deftp @deftp {Data Type} nscd-cache Data type representing a cache database of nscd and its parameters. @table @asis @item @code{database} This is a symbol representing the name of the database to be cached. Valid values are @code{passwd}, @code{group}, @code{hosts}, and @code{services}, which designate the corresponding NSS database (@pxref{NSS Basics,,, libc, The GNU C Library Reference Manual}). @item @code{positive-time-to-live} @itemx @code{negative-time-to-live} (default: @code{20}) A number representing the number of seconds during which a positive or negative lookup result remains in cache. @item @code{check-files?} (default: @code{#t}) Whether to check for updates of the files corresponding to @var{database}. For instance, when @var{database} is @code{hosts}, setting this flag instructs nscd to check for updates in @file{/etc/hosts} and to take them into account. @item @code{persistent?} (default: @code{#t}) Whether the cache should be stored persistently on disk. @item @code{shared?} (default: @code{#t}) Whether the cache should be shared among users. @item @code{max-database-size} (default: 32@tie{}MiB) Maximum size in bytes of the database cache. @c XXX: 'suggested-size' and 'auto-propagate?' seem to be expert @c settings, so leave them out. @end table @end deftp @defvr {Scheme Variable} %nscd-default-caches List of @code{} objects used by default by @code{nscd-configuration} (see above). It enables persistent and aggressive caching of service and host name lookups. The latter provides better host name lookup performance, resilience in the face of unreliable name servers, and also better privacy---often the result of host name lookups is in local cache, so external name servers do not even need to be queried. @end defvr @anchor{syslog-configuration-type} @cindex syslog @cindex logging @deftp {Data Type} syslog-configuration This data type represents the configuration of the syslog daemon. @table @asis @item @code{syslogd} (default: @code{#~(string-append #$inetutils "/libexec/syslogd")}) The syslog daemon to use. @item @code{config-file} (default: @code{%default-syslog.conf}) The syslog configuration file to use. @end table @end deftp @anchor{syslog-service} @cindex syslog @deffn {Scheme Procedure} syslog-service @var{config} Return a service that runs a syslog daemon according to @var{config}. @xref{syslogd invocation,,, inetutils, GNU Inetutils}, for more information on the configuration file syntax. @end deffn @defvr {Scheme Variable} guix-service-type This is the type of the service that runs the build daemon, @command{guix-daemon} (@pxref{Invoking guix-daemon}). Its value must be a @code{guix-configuration} record as described below. @end defvr @anchor{guix-configuration-type} @deftp {Data Type} guix-configuration This data type represents the configuration of the Guix build daemon. @xref{Invoking guix-daemon}, for more information. @table @asis @item @code{guix} (default: @var{guix}) The Guix package to use. @item @code{build-group} (default: @code{"guixbuild"}) Name of the group for build user accounts. @item @code{build-accounts} (default: @code{10}) Number of build user accounts to create. @item @code{authorize-key?} (default: @code{#t}) @cindex substitutes, authorization thereof Whether to authorize the substitute keys listed in @code{authorized-keys}---by default that of @code{@value{SUBSTITUTE-SERVER}} (@pxref{Substitutes}). When @code{authorize-key?} is true, @file{/etc/guix/acl} cannot be changed by invoking @command{guix archive --authorize}. You must instead adjust @code{guix-configuration} as you wish and reconfigure the system. This ensures that your operating system configuration file is self-contained. @quotation Note When booting or reconfiguring to a system where @code{authorize-key?} is true, the existing @file{/etc/guix/acl} file is backed up as @file{/etc/guix/acl.bak} if it was determined to be a manually modified file. This is to facilitate migration from earlier versions, which allowed for in-place modifications to @file{/etc/guix/acl}. @end quotation @vindex %default-authorized-guix-keys @item @code{authorized-keys} (default: @code{%default-authorized-guix-keys}) The list of authorized key files for archive imports, as a list of string-valued gexps (@pxref{Invoking guix archive}). By default, it contains that of @code{@value{SUBSTITUTE-SERVER}} (@pxref{Substitutes}). See @code{substitute-urls} below for an example on how to change it. @item @code{use-substitutes?} (default: @code{#t}) Whether to use substitutes. @item @code{substitute-urls} (default: @code{%default-substitute-urls}) The list of URLs where to look for substitutes by default. Suppose you would like to fetch substitutes from @code{guix.example.org} in addition to @code{@value{SUBSTITUTE-SERVER}}. You will need to do two things: (1) add @code{guix.example.org} to @code{substitute-urls}, and (2) authorize its signing key, having done appropriate checks (@pxref{Substitute Server Authorization}). The configuration below does exactly that: @lisp (guix-configuration (substitute-urls (append (list "https://guix.example.org") %default-substitute-urls)) (authorized-keys (append (list (local-file "./guix.example.org-key.pub")) %default-authorized-guix-keys))) @end lisp This example assumes that the file @file{./guix.example.org-key.pub} contains the public key that @code{guix.example.org} uses to sign substitutes. @item @code{max-silent-time} (default: @code{0}) @itemx @code{timeout} (default: @code{0}) The number of seconds of silence and the number of seconds of activity, respectively, after which a build process times out. A value of zero disables the timeout. @item @code{log-compression} (default: @code{'bzip2}) The type of compression used for build logs---one of @code{gzip}, @code{bzip2}, or @code{none}. @item @code{discover?} (default: @code{#f}) Whether to discover substitute servers on the local network using mDNS and DNS-SD. @item @code{extra-options} (default: @code{'()}) List of extra command-line options for @command{guix-daemon}. @item @code{log-file} (default: @code{"/var/log/guix-daemon.log"}) File where @command{guix-daemon}'s standard output and standard error are written. @cindex HTTP proxy, for @code{guix-daemon} @cindex proxy, for @code{guix-daemon} HTTP access @item @code{http-proxy} (default: @code{#f}) The URL of the HTTP and HTTPS proxy used for downloading fixed-output derivations and substitutes. It is also possible to change the daemon's proxy at run time through the @code{set-http-proxy} action, which restarts it: @example herd set-http-proxy guix-daemon http://localhost:8118 @end example To clear the proxy settings, run: @example herd set-http-proxy guix-daemon @end example @item @code{tmpdir} (default: @code{#f}) A directory path where the @command{guix-daemon} will perform builds. @end table @end deftp @deffn {Scheme Procedure} udev-service [#:udev @var{eudev} #:rules @code{'()}] Run @var{udev}, which populates the @file{/dev} directory dynamically. udev rules can be provided as a list of files through the @var{rules} variable. The procedures @code{udev-rule}, @code{udev-rules-service} and @code{file->udev-rule} from @code{(gnu services base)} simplify the creation of such rule files. The @command{herd rules udev} command, as root, returns the name of the directory containing all the active udev rules. @end deffn @deffn {Scheme Procedure} udev-rule [@var{file-name} @var{contents}] Return a udev-rule file named @var{file-name} containing the rules defined by the @var{contents} literal. In the following example, a rule for a USB device is defined to be stored in the file @file{90-usb-thing.rules}. The rule runs a script upon detecting a USB device with a given product identifier. @lisp (define %example-udev-rule (udev-rule "90-usb-thing.rules" (string-append "ACTION==\"add\", SUBSYSTEM==\"usb\", " "ATTR@{product@}==\"Example\", " "RUN+=\"/path/to/script\""))) @end lisp @end deffn @deffn {Scheme Procedure} udev-rules-service [@var{name} @var{rules}] @ [#:groups @var{groups}] Return a service that extends @code{udev-service-type } with @var{rules} and @code{account-service-type} with @var{groups} as system groups. This works by creating a singleton service type @code{@var{name}-udev-rules}, of which the returned service is an instance. Here we show how it can be used to extend @code{udev-service-type} with the previously defined rule @code{%example-udev-rule}. @lisp (operating-system ;; @dots{} (services (cons (udev-rules-service 'usb-thing %example-udev-rule) %desktop-services))) @end lisp @end deffn @deffn {Scheme Procedure} file->udev-rule [@var{file-name} @var{file}] Return a udev file named @var{file-name} containing the rules defined within @var{file}, a file-like object. The following example showcases how we can use an existing rule file. @lisp (use-modules (guix download) ;for url-fetch (guix packages) ;for origin @dots{}) (define %android-udev-rules (file->udev-rule "51-android-udev.rules" (let ((version "20170910")) (origin (method url-fetch) (uri (string-append "https://raw.githubusercontent.com/M0Rf30/" "android-udev-rules/" version "/51-android.rules")) (sha256 (base32 "0lmmagpyb6xsq6zcr2w1cyx9qmjqmajkvrdbhjx32gqf1d9is003")))))) @end lisp @end deffn Additionally, Guix package definitions can be included in @var{rules} in order to extend the udev rules with the definitions found under their @file{lib/udev/rules.d} sub-directory. In lieu of the previous @var{file->udev-rule} example, we could have used the @var{android-udev-rules} package which exists in Guix in the @code{(gnu packages android)} module. The following example shows how to use the @var{android-udev-rules} package so that the Android tool @command{adb} can detect devices without root privileges. It also details how to create the @code{adbusers} group, which is required for the proper functioning of the rules defined within the @code{android-udev-rules} package. To create such a group, we must define it both as part of the @code{supplementary-groups} of our @code{user-account} declaration, as well as in the @var{groups} of the @code{udev-rules-service} procedure. @lisp (use-modules (gnu packages android) ;for android-udev-rules (gnu system shadow) ;for user-group @dots{}) (operating-system ;; @dots{} (users (cons (user-account ;; @dots{} (supplementary-groups '("adbusers" ;for adb "wheel" "netdev" "audio" "video"))))) ;; @dots{} (services (cons (udev-rules-service 'android android-udev-rules #:groups '("adbusers")) %desktop-services))) @end lisp @defvr {Scheme Variable} urandom-seed-service-type Save some entropy in @code{%random-seed-file} to seed @file{/dev/urandom} when rebooting. It also tries to seed @file{/dev/urandom} from @file{/dev/hwrng} while booting, if @file{/dev/hwrng} exists and is readable. @end defvr @defvr {Scheme Variable} %random-seed-file This is the name of the file where some random bytes are saved by @var{urandom-seed-service} to seed @file{/dev/urandom} when rebooting. It defaults to @file{/var/lib/random-seed}. @end defvr @cindex mouse @cindex gpm @defvr {Scheme Variable} gpm-service-type This is the type of the service that runs GPM, the @dfn{general-purpose mouse daemon}, which provides mouse support to the Linux console. GPM allows users to use the mouse in the console, notably to select, copy, and paste text. The value for services of this type must be a @code{gpm-configuration} (see below). This service is not part of @code{%base-services}. @end defvr @deftp {Data Type} gpm-configuration Data type representing the configuration of GPM. @table @asis @item @code{options} (default: @code{%default-gpm-options}) Command-line options passed to @command{gpm}. The default set of options instruct @command{gpm} to listen to mouse events on @file{/dev/input/mice}. @xref{Command Line,,, gpm, gpm manual}, for more information. @item @code{gpm} (default: @code{gpm}) The GPM package to use. @end table @end deftp @anchor{guix-publish-service-type} @deffn {Scheme Variable} guix-publish-service-type This is the service type for @command{guix publish} (@pxref{Invoking guix publish}). Its value must be a @code{guix-publish-configuration} object, as described below. This assumes that @file{/etc/guix} already contains a signing key pair as created by @command{guix archive --generate-key} (@pxref{Invoking guix archive}). If that is not the case, the service will fail to start. @end deffn @deftp {Data Type} guix-publish-configuration Data type representing the configuration of the @code{guix publish} service. @table @asis @item @code{guix} (default: @code{guix}) The Guix package to use. @item @code{port} (default: @code{80}) The TCP port to listen for connections. @item @code{host} (default: @code{"localhost"}) The host (and thus, network interface) to listen to. Use @code{"0.0.0.0"} to listen on all the network interfaces. @item @code{advertise?} (default: @code{#f}) When true, advertise the service on the local network @i{via} the DNS-SD protocol, using Avahi. This allows neighboring Guix devices with discovery on (see @code{guix-configuration} above) to discover this @command{guix publish} instance and to automatically download substitutes from it. @item @code{compression} (default: @code{'(("gzip" 3))}) This is a list of compression method/level tuple used when compressing substitutes. For example, to compress all substitutes with @emph{both} lzip at level 7 and gzip at level 9, write: @lisp '(("lzip" 7) ("gzip" 9)) @end lisp Level 9 achieves the best compression ratio at the expense of increased CPU usage, whereas level 1 achieves fast compression. @xref{Invoking guix publish}, for more information on the available compression methods and the tradeoffs involved. An empty list disables compression altogether. @item @code{nar-path} (default: @code{"nar"}) The URL path at which ``nars'' can be fetched. @xref{Invoking guix publish, @option{--nar-path}}, for details. @item @code{cache} (default: @code{#f}) When it is @code{#f}, disable caching and instead generate archives on demand. Otherwise, this should be the name of a directory---e.g., @code{"/var/cache/guix/publish"}---where @command{guix publish} caches archives and meta-data ready to be sent. @xref{Invoking guix publish, @option{--cache}}, for more information on the tradeoffs involved. @item @code{workers} (default: @code{#f}) When it is an integer, this is the number of worker threads used for caching; when @code{#f}, the number of processors is used. @xref{Invoking guix publish, @option{--workers}}, for more information. @item @code{cache-bypass-threshold} (default: 10 MiB) When @code{cache} is true, this is the maximum size in bytes of a store item for which @command{guix publish} may bypass its cache in case of a cache miss. @xref{Invoking guix publish, @option{--cache-bypass-threshold}}, for more information. @item @code{ttl} (default: @code{#f}) When it is an integer, this denotes the @dfn{time-to-live} in seconds of the published archives. @xref{Invoking guix publish, @option{--ttl}}, for more information. @end table @end deftp @anchor{rngd-service} @deffn {Scheme Procedure} rngd-service [#:rng-tools @var{rng-tools}] @ [#:device "/dev/hwrng"] Return a service that runs the @command{rngd} program from @var{rng-tools} to add @var{device} to the kernel's entropy pool. The service will fail if @var{device} does not exist. @end deffn @anchor{pam-limits-service} @cindex session limits @cindex ulimit @cindex priority @cindex realtime @cindex jackd @deffn {Scheme Procedure} pam-limits-service [#:limits @code{'()}] Return a service that installs a configuration file for the @uref{http://linux-pam.org/Linux-PAM-html/sag-pam_limits.html, @code{pam_limits} module}. The procedure optionally takes a list of @code{pam-limits-entry} values, which can be used to specify @code{ulimit} limits and nice priority limits to user sessions. The following limits definition sets two hard and soft limits for all login sessions of users in the @code{realtime} group: @lisp (pam-limits-service (list (pam-limits-entry "@@realtime" 'both 'rtprio 99) (pam-limits-entry "@@realtime" 'both 'memlock 'unlimited))) @end lisp The first entry increases the maximum realtime priority for non-privileged processes; the second entry lifts any restriction of the maximum address space that can be locked in memory. These settings are commonly used for real-time audio systems. @end deffn @node Scheduled Job Execution @subsection Scheduled Job Execution @cindex cron @cindex mcron @cindex scheduling jobs The @code{(gnu services mcron)} module provides an interface to GNU@tie{}mcron, a daemon to run jobs at scheduled times (@pxref{Top,,, mcron, GNU@tie{}mcron}). GNU@tie{}mcron is similar to the traditional Unix @command{cron} daemon; the main difference is that it is implemented in Guile Scheme, which provides a lot of flexibility when specifying the scheduling of jobs and their actions. The example below defines an operating system that runs the @command{updatedb} (@pxref{Invoking updatedb,,, find, Finding Files}) and the @command{guix gc} commands (@pxref{Invoking guix gc}) daily, as well as the @command{mkid} command on behalf of an unprivileged user (@pxref{mkid invocation,,, idutils, ID Database Utilities}). It uses gexps to introduce job definitions that are passed to mcron (@pxref{G-Expressions}). @lisp (use-modules (guix) (gnu) (gnu services mcron)) (use-package-modules base idutils) (define updatedb-job ;; Run 'updatedb' at 3AM every day. Here we write the ;; job's action as a Scheme procedure. #~(job '(next-hour '(3)) (lambda () (execl (string-append #$findutils "/bin/updatedb") "updatedb" "--prunepaths=/tmp /var/tmp /gnu/store")))) (define garbage-collector-job ;; Collect garbage 5 minutes after midnight every day. ;; The job's action is a shell command. #~(job "5 0 * * *" ;Vixie cron syntax "guix gc -F 1G")) (define idutils-job ;; Update the index database as user "charlie" at 12:15PM ;; and 19:15PM. This runs from the user's home directory. #~(job '(next-minute-from (next-hour '(12 19)) '(15)) (string-append #$idutils "/bin/mkid src") #:user "charlie")) (operating-system ;; @dots{} ;; %BASE-SERVICES already includes an instance of ;; 'mcron-service-type', which we extend with additional ;; jobs using 'simple-service'. (services (cons (simple-service 'my-cron-jobs mcron-service-type (list garbage-collector-job updatedb-job idutils-job)) %base-services))) @end lisp For more complex jobs defined in Scheme where you need control over the top level, for instance to introduce a @code{use-modules} form, you can move your code to a separate program using the @code{program-file} procedure of the @code{(guix gexp)} module (@pxref{G-Expressions}). The example below illustrates that. @lisp (define %battery-alert-job ;; Beep when the battery percentage falls below %MIN-LEVEL. #~(job '(next-minute (range 0 60 1)) #$(program-file "battery-alert.scm" (with-imported-modules (source-module-closure '((guix build utils))) #~(begin (use-modules (guix build utils) (ice-9 popen) (ice-9 regex) (ice-9 textual-ports) (srfi srfi-2)) (define %min-level 20) (setenv "LC_ALL" "C") ;ensure English output (and-let* ((input-pipe (open-pipe* OPEN_READ #$(file-append acpi "/bin/acpi"))) (output (get-string-all input-pipe)) (m (string-match "Discharging, ([0-9]+)%" output)) (level (string->number (match:substring m 1))) ((< level %min-level))) (format #t "warning: Battery level is low (~a%)~%" level) (invoke #$(file-append beep "/bin/beep") "-r5"))))))) @end lisp @xref{Guile Syntax, mcron job specifications,, mcron, GNU@tie{}mcron}, for more information on mcron job specifications. Below is the reference of the mcron service. On a running system, you can use the @code{schedule} action of the service to visualize the mcron jobs that will be executed next: @example # herd schedule mcron @end example @noindent The example above lists the next five tasks that will be executed, but you can also specify the number of tasks to display: @example # herd schedule mcron 10 @end example @defvr {Scheme Variable} mcron-service-type This is the type of the @code{mcron} service, whose value is an @code{mcron-configuration} object. This service type can be the target of a service extension that provides it additional job specifications (@pxref{Service Composition}). In other words, it is possible to define services that provide additional mcron jobs to run. @end defvr @deftp {Data Type} mcron-configuration Data type representing the configuration of mcron. @table @asis @item @code{mcron} (default: @var{mcron}) The mcron package to use. @item @code{jobs} This is a list of gexps (@pxref{G-Expressions}), where each gexp corresponds to an mcron job specification (@pxref{Syntax, mcron job specifications,, mcron, GNU@tie{}mcron}). @end table @end deftp @node Log Rotation @subsection Log Rotation @cindex rottlog @cindex log rotation @cindex logging Log files such as those found in @file{/var/log} tend to grow endlessly, so it's a good idea to @dfn{rotate} them once in a while---i.e., archive their contents in separate files, possibly compressed. The @code{(gnu services admin)} module provides an interface to GNU@tie{}Rot[t]log, a log rotation tool (@pxref{Top,,, rottlog, GNU Rot[t]log Manual}). This service is part of @code{%base-services}, and thus enabled by default, with the default settings, for commonly encountered log files. The example below shows how to extend it with an additional @dfn{rotation}, should you need to do that (usually, services that produce log files already take care of that): @lisp (use-modules (guix) (gnu)) (use-service-modules admin) (define my-log-files ;; Log files that I want to rotate. '("/var/log/something.log" "/var/log/another.log")) (operating-system ;; @dots{} (services (cons (simple-service 'rotate-my-stuff rottlog-service-type (list (log-rotation (frequency 'daily) (files my-log-files)))) %base-services))) @end lisp @defvr {Scheme Variable} rottlog-service-type This is the type of the Rottlog service, whose value is a @code{rottlog-configuration} object. Other services can extend this one with new @code{log-rotation} objects (see below), thereby augmenting the set of files to be rotated. This service type can define mcron jobs (@pxref{Scheduled Job Execution}) to run the rottlog service. @end defvr @deftp {Data Type} rottlog-configuration Data type representing the configuration of rottlog. @table @asis @item @code{rottlog} (default: @code{rottlog}) The Rottlog package to use. @item @code{rc-file} (default: @code{(file-append rottlog "/etc/rc")}) The Rottlog configuration file to use (@pxref{Mandatory RC Variables,,, rottlog, GNU Rot[t]log Manual}). @item @code{rotations} (default: @code{%default-rotations}) A list of @code{log-rotation} objects as defined below. @item @code{jobs} This is a list of gexps where each gexp corresponds to an mcron job specification (@pxref{Scheduled Job Execution}). @end table @end deftp @deftp {Data Type} log-rotation Data type representing the rotation of a group of log files. Taking an example from the Rottlog manual (@pxref{Period Related File Examples,,, rottlog, GNU Rot[t]log Manual}), a log rotation might be defined like this: @lisp (log-rotation (frequency 'daily) (files '("/var/log/apache/*")) (options '("storedir apache-archives" "rotate 6" "notifempty" "nocompress"))) @end lisp The list of fields is as follows: @table @asis @item @code{frequency} (default: @code{'weekly}) The log rotation frequency, a symbol. @item @code{files} The list of files or file glob patterns to rotate. @item @code{options} (default: @code{'()}) The list of rottlog options for this rotation (@pxref{Configuration parameters,,, rottlog, GNU Rot[t]lg Manual}). @item @code{post-rotate} (default: @code{#f}) Either @code{#f} or a gexp to execute once the rotation has completed. @end table @end deftp @defvr {Scheme Variable} %default-rotations Specifies weekly rotation of @code{%rotated-files} and of @file{/var/log/guix-daemon.log}. @end defvr @defvr {Scheme Variable} %rotated-files The list of syslog-controlled files to be rotated. By default it is: @code{'("/var/log/messages" "/var/log/secure" "/var/log/debug" \ "/var/log/maillog")}. @end defvr @node Networking Services @subsection Networking Services The @code{(gnu services networking)} module provides services to configure the network interface. @cindex DHCP, networking service @defvr {Scheme Variable} dhcp-client-service-type This is the type of services that run @var{dhcp}, a Dynamic Host Configuration Protocol (DHCP) client, on all the non-loopback network interfaces. Its value is the DHCP client package to use, @code{isc-dhcp} by default. @end defvr @deffn {Scheme Procedure} dhcpd-service-type This type defines a service that runs a DHCP daemon. To create a service of this type, you must supply a @code{}. For example: @lisp (service dhcpd-service-type (dhcpd-configuration (config-file (local-file "my-dhcpd.conf")) (interfaces '("enp0s25")))) @end lisp @end deffn @deftp {Data Type} dhcpd-configuration @table @asis @item @code{package} (default: @code{isc-dhcp}) The package that provides the DHCP daemon. This package is expected to provide the daemon at @file{sbin/dhcpd} relative to its output directory. The default package is the @uref{https://www.isc.org/products/DHCP, ISC's DHCP server}. @item @code{config-file} (default: @code{#f}) The configuration file to use. This is required. It will be passed to @code{dhcpd} via its @code{-cf} option. This may be any ``file-like'' object (@pxref{G-Expressions, file-like objects}). See @code{man dhcpd.conf} for details on the configuration file syntax. @item @code{version} (default: @code{"4"}) The DHCP version to use. The ISC DHCP server supports the values ``4'', ``6'', and ``4o6''. These correspond to the @code{dhcpd} program options @code{-4}, @code{-6}, and @code{-4o6}. See @code{man dhcpd} for details. @item @code{run-directory} (default: @code{"/run/dhcpd"}) The run directory to use. At service activation time, this directory will be created if it does not exist. @item @code{pid-file} (default: @code{"/run/dhcpd/dhcpd.pid"}) The PID file to use. This corresponds to the @code{-pf} option of @code{dhcpd}. See @code{man dhcpd} for details. @item @code{interfaces} (default: @code{'()}) The names of the network interfaces on which dhcpd should listen for broadcasts. If this list is not empty, then its elements (which must be strings) will be appended to the @code{dhcpd} invocation when starting the daemon. It may not be necessary to explicitly specify any interfaces here; see @code{man dhcpd} for details. @end table @end deftp @defvr {Scheme Variable} static-networking-service-type This is the type for statically-configured network interfaces. @c TODO Document data structures. @end defvr @deffn {Scheme Procedure} static-networking-service @var{interface} @var{ip} @ [#:netmask #f] [#:gateway #f] [#:name-servers @code{'()}] @ [#:requirement @code{'(udev)}] Return a service that starts @var{interface} with address @var{ip}. If @var{netmask} is true, use it as the network mask. If @var{gateway} is true, it must be a string specifying the default network gateway. @var{requirement} can be used to declare a dependency on another service before configuring the interface. This procedure can be called several times, one for each network interface of interest. Behind the scenes what it does is extend @code{static-networking-service-type} with additional network interfaces to handle. For example: @lisp (static-networking-service "eno1" "192.168.1.82" #:gateway "192.168.1.2" #:name-servers '("192.168.1.2")) @end lisp @end deffn @cindex wicd @cindex wireless @cindex WiFi @cindex network management @deffn {Scheme Procedure} wicd-service [#:wicd @var{wicd}] Return a service that runs @url{https://launchpad.net/wicd,Wicd}, a network management daemon that aims to simplify wired and wireless networking. This service adds the @var{wicd} package to the global profile, providing several commands to interact with the daemon and configure networking: @command{wicd-client}, a graphical user interface, and the @command{wicd-cli} and @command{wicd-curses} user interfaces. @end deffn @cindex ModemManager @defvr {Scheme Variable} modem-manager-service-type This is the service type for the @uref{https://wiki.gnome.org/Projects/ModemManager, ModemManager} service. The value for this service type is a @code{modem-manager-configuration} record. This service is part of @code{%desktop-services} (@pxref{Desktop Services}). @end defvr @deftp {Data Type} modem-manager-configuration Data type representing the configuration of ModemManager. @table @asis @item @code{modem-manager} (default: @code{modem-manager}) The ModemManager package to use. @end table @end deftp @cindex USB_ModeSwitch @cindex Modeswitching @defvr {Scheme Variable} usb-modeswitch-service-type This is the service type for the @uref{https://www.draisberghof.de/usb_modeswitch/, USB_ModeSwitch} service. The value for this service type is a @code{usb-modeswitch-configuration} record. When plugged in, some USB modems (and other USB devices) initially present themselves as a read-only storage medium and not as a modem. They need to be @dfn{modeswitched} before they are usable. The USB_ModeSwitch service type installs udev rules to automatically modeswitch these devices when they are plugged in. This service is part of @code{%desktop-services} (@pxref{Desktop Services}). @end defvr @deftp {Data Type} usb-modeswitch-configuration Data type representing the configuration of USB_ModeSwitch. @table @asis @item @code{usb-modeswitch} (default: @code{usb-modeswitch}) The USB_ModeSwitch package providing the binaries for modeswitching. @item @code{usb-modeswitch-data} (default: @code{usb-modeswitch-data}) The package providing the device data and udev rules file used by USB_ModeSwitch. @item @code{config-file} (default: @code{#~(string-append #$usb-modeswitch:dispatcher "/etc/usb_modeswitch.conf")}) Which config file to use for the USB_ModeSwitch dispatcher. By default the config file shipped with USB_ModeSwitch is used which disables logging to @file{/var/log} among other default settings. If set to @code{#f}, no config file is used. @end table @end deftp @cindex NetworkManager @defvr {Scheme Variable} network-manager-service-type This is the service type for the @uref{https://wiki.gnome.org/Projects/NetworkManager, NetworkManager} service. The value for this service type is a @code{network-manager-configuration} record. This service is part of @code{%desktop-services} (@pxref{Desktop Services}). @end defvr @deftp {Data Type} network-manager-configuration Data type representing the configuration of NetworkManager. @table @asis @item @code{network-manager} (default: @code{network-manager}) The NetworkManager package to use. @item @code{dns} (default: @code{"default"}) Processing mode for DNS, which affects how NetworkManager uses the @code{resolv.conf} configuration file. @table @samp @item default NetworkManager will update @code{resolv.conf} to reflect the nameservers provided by currently active connections. @item dnsmasq NetworkManager will run @code{dnsmasq} as a local caching nameserver, using a @dfn{conditional forwarding} configuration if you are connected to a VPN, and then update @code{resolv.conf} to point to the local nameserver. With this setting, you can share your network connection. For example when you want to share your network connection to another laptop @i{via} an Ethernet cable, you can open @command{nm-connection-editor} and configure the Wired connection's method for IPv4 and IPv6 to be ``Shared to other computers'' and reestablish the connection (or reboot). You can also set up a @dfn{host-to-guest connection} to QEMU VMs (@pxref{Installing Guix in a VM}). With a host-to-guest connection, you can e.g.@: access a Web server running on the VM (@pxref{Web Services}) from a Web browser on your host system, or connect to the VM @i{via} SSH (@pxref{Networking Services, @code{openssh-service-type}}). To set up a host-to-guest connection, run this command once: @example nmcli connection add type tun \ connection.interface-name tap0 \ tun.mode tap tun.owner $(id -u) \ ipv4.method shared \ ipv4.addresses 172.28.112.1/24 @end example Then each time you launch your QEMU VM (@pxref{Running Guix in a VM}), pass @option{-nic tap,ifname=tap0,script=no,downscript=no} to @command{qemu-system-...}. @item none NetworkManager will not modify @code{resolv.conf}. @end table @item @code{vpn-plugins} (default: @code{'()}) This is the list of available plugins for virtual private networks (VPNs). An example of this is the @code{network-manager-openvpn} package, which allows NetworkManager to manage VPNs @i{via} OpenVPN. @end table @end deftp @cindex Connman @deffn {Scheme Variable} connman-service-type This is the service type to run @url{https://01.org/connman,Connman}, a network connection manager. Its value must be an @code{connman-configuration} record as in this example: @lisp (service connman-service-type (connman-configuration (disable-vpn? #t))) @end lisp See below for details about @code{connman-configuration}. @end deffn @deftp {Data Type} connman-configuration Data Type representing the configuration of connman. @table @asis @item @code{connman} (default: @var{connman}) The connman package to use. @item @code{disable-vpn?} (default: @code{#f}) When true, disable connman's vpn plugin. @end table @end deftp @cindex WPA Supplicant @defvr {Scheme Variable} wpa-supplicant-service-type This is the service type to run @url{https://w1.fi/wpa_supplicant/,WPA supplicant}, an authentication daemon required to authenticate against encrypted WiFi or ethernet networks. @end defvr @deftp {Data Type} wpa-supplicant-configuration Data type representing the configuration of WPA Supplicant. It takes the following parameters: @table @asis @item @code{wpa-supplicant} (default: @code{wpa-supplicant}) The WPA Supplicant package to use. @item @code{requirement} (default: @code{'(user-processes loopback syslogd)} List of services that should be started before WPA Supplicant starts. @item @code{dbus?} (default: @code{#t}) Whether to listen for requests on D-Bus. @item @code{pid-file} (default: @code{"/var/run/wpa_supplicant.pid"}) Where to store the PID file. @item @code{interface} (default: @code{#f}) If this is set, it must specify the name of a network interface that WPA supplicant will control. @item @code{config-file} (default: @code{#f}) Optional configuration file to use. @item @code{extra-options} (default: @code{'()}) List of additional command-line arguments to pass to the daemon. @end table @end deftp @cindex hostapd service, for Wi-Fi access points @cindex Wi-Fi access points, hostapd service @defvr {Scheme Variable} hostapd-service-type This is the service type to run the @uref{https://w1.fi/hostapd/, hostapd} daemon to set up WiFi (IEEE 802.11) access points and authentication servers. Its associated value must be a @code{hostapd-configuration} as shown below: @lisp ;; Use wlan1 to run the access point for "My Network". (service hostapd-service-type (hostapd-configuration (interface "wlan1") (ssid "My Network") (channel 12))) @end lisp @end defvr @deftp {Data Type} hostapd-configuration This data type represents the configuration of the hostapd service, with the following fields: @table @asis @item @code{package} (default: @code{hostapd}) The hostapd package to use. @item @code{interface} (default: @code{"wlan0"}) The network interface to run the WiFi access point. @item @code{ssid} The SSID (@dfn{service set identifier}), a string that identifies this network. @item @code{broadcast-ssid?} (default: @code{#t}) Whether to broadcast this SSID. @item @code{channel} (default: @code{1}) The WiFi channel to use. @item @code{driver} (default: @code{"nl80211"}) The driver interface type. @code{"nl80211"} is used with all Linux mac80211 drivers. Use @code{"none"} if building hostapd as a standalone RADIUS server that does # not control any wireless/wired driver. @item @code{extra-settings} (default: @code{""}) Extra settings to append as-is to the hostapd configuration file. See @uref{https://w1.fi/cgit/hostap/plain/hostapd/hostapd.conf} for the configuration file reference. @end table @end deftp @defvr {Scheme Variable} simulated-wifi-service-type This is the type of a service to simulate WiFi networking, which can be useful in virtual machines for testing purposes. The service loads the Linux kernel @uref{https://www.kernel.org/doc/html/latest/networking/mac80211_hwsim/mac80211_hwsim.html, @code{mac80211_hwsim} module} and starts hostapd to create a pseudo WiFi network that can be seen on @code{wlan0}, by default. The service's value is a @code{hostapd-configuration} record. @end defvr @cindex iptables @defvr {Scheme Variable} iptables-service-type This is the service type to set up an iptables configuration. iptables is a packet filtering framework supported by the Linux kernel. This service supports configuring iptables for both IPv4 and IPv6. A simple example configuration rejecting all incoming connections except those to the ssh port 22 is shown below. @lisp (service iptables-service-type (iptables-configuration (ipv4-rules (plain-file "iptables.rules" "*filter :INPUT ACCEPT :FORWARD ACCEPT :OUTPUT ACCEPT -A INPUT -p tcp --dport 22 -j ACCEPT -A INPUT -j REJECT --reject-with icmp-port-unreachable COMMIT ")) (ipv6-rules (plain-file "ip6tables.rules" "*filter :INPUT ACCEPT :FORWARD ACCEPT :OUTPUT ACCEPT -A INPUT -p tcp --dport 22 -j ACCEPT -A INPUT -j REJECT --reject-with icmp6-port-unreachable COMMIT ")))) @end lisp @end defvr @deftp {Data Type} iptables-configuration The data type representing the configuration of iptables. @table @asis @item @code{iptables} (default: @code{iptables}) The iptables package that provides @code{iptables-restore} and @code{ip6tables-restore}. @item @code{ipv4-rules} (default: @code{%iptables-accept-all-rules}) The iptables rules to use. It will be passed to @code{iptables-restore}. This may be any ``file-like'' object (@pxref{G-Expressions, file-like objects}). @item @code{ipv6-rules} (default: @code{%iptables-accept-all-rules}) The ip6tables rules to use. It will be passed to @code{ip6tables-restore}. This may be any ``file-like'' object (@pxref{G-Expressions, file-like objects}). @end table @end deftp @cindex nftables @defvr {Scheme Variable} nftables-service-type This is the service type to set up a nftables configuration. nftables is a netfilter project that aims to replace the existing iptables, ip6tables, arptables and ebtables framework. It provides a new packet filtering framework, a new user-space utility @command{nft}, and a compatibility layer for iptables. This service comes with a default ruleset @code{%default-nftables-ruleset} that rejecting all incomming connections except those to the ssh port 22. To use it, simply write: @lisp (service nftables-service-type) @end lisp @end defvr @deftp {Data Type} nftables-configuration The data type representing the configuration of nftables. @table @asis @item @code{package} (default: @code{nftables}) The nftables package that provides @command{nft}. @item @code{ruleset} (default: @code{%default-nftables-ruleset}) The nftables ruleset to use. This may be any ``file-like'' object (@pxref{G-Expressions, file-like objects}). @end table @end deftp @cindex NTP (Network Time Protocol), service @cindex ntpd, service for the Network Time Protocol daemon @cindex real time clock @defvr {Scheme Variable} ntp-service-type This is the type of the service running the @uref{https://www.ntp.org, Network Time Protocol (NTP)} daemon, @command{ntpd}. The daemon will keep the system clock synchronized with that of the specified NTP servers. The value of this service is an @code{ntpd-configuration} object, as described below. @end defvr @deftp {Data Type} ntp-configuration This is the data type for the NTP service configuration. @table @asis @item @code{servers} (default: @code{%ntp-servers}) This is the list of servers (@code{} records) with which @command{ntpd} will be synchronized. See the @code{ntp-server} data type definition below. @item @code{allow-large-adjustment?} (default: @code{#t}) This determines whether @command{ntpd} is allowed to make an initial adjustment of more than 1,000 seconds. @item @code{ntp} (default: @code{ntp}) The NTP package to use. @end table @end deftp @defvr {Scheme Variable} %ntp-servers List of host names used as the default NTP servers. These are servers of the @uref{https://www.ntppool.org/en/, NTP Pool Project}. @end defvr @deftp {Data Type} ntp-server The data type representing the configuration of a NTP server. @table @asis @item @code{type} (default: @code{'server}) The type of the NTP server, given as a symbol. One of @code{'pool}, @code{'server}, @code{'peer}, @code{'broadcast} or @code{'manycastclient}. @item @code{address} The address of the server, as a string. @item @code{options} NTPD options to use with that specific server, given as a list of option names and/or of option names and values tuples. The following example define a server to use with the options @option{iburst} and @option{prefer}, as well as @option{version} 3 and a @option{maxpoll} time of 16 seconds. @example (ntp-server (type 'server) (address "some.ntp.server.org") (options `(iburst (version 3) (maxpoll 16) prefer)))) @end example @end table @end deftp @cindex OpenNTPD @deffn {Scheme Procedure} openntpd-service-type Run the @command{ntpd}, the Network Time Protocol (NTP) daemon, as implemented by @uref{http://www.openntpd.org, OpenNTPD}. The daemon will keep the system clock synchronized with that of the given servers. @lisp (service openntpd-service-type (openntpd-configuration (listen-on '("127.0.0.1" "::1")) (sensor '("udcf0 correction 70000")) (constraint-from '("www.gnu.org")) (constraints-from '("https://www.google.com/")) (allow-large-adjustment? #t))) @end lisp @end deffn @defvr {Scheme Variable} %openntpd-servers This variable is a list of the server addresses defined in @code{%ntp-servers}. @end defvr @deftp {Data Type} openntpd-configuration @table @asis @item @code{openntpd} (default: @code{(file-append openntpd "/sbin/ntpd")}) The openntpd executable to use. @item @code{listen-on} (default: @code{'("127.0.0.1" "::1")}) A list of local IP addresses or hostnames the ntpd daemon should listen on. @item @code{query-from} (default: @code{'()}) A list of local IP address the ntpd daemon should use for outgoing queries. @item @code{sensor} (default: @code{'()}) Specify a list of timedelta sensor devices ntpd should use. @code{ntpd} will listen to each sensor that actually exists and ignore non-existent ones. See @uref{https://man.openbsd.org/ntpd.conf, upstream documentation} for more information. @item @code{server} (default: @code{'()}) Specify a list of IP addresses or hostnames of NTP servers to synchronize to. @item @code{servers} (default: @code{%openntp-servers}) Specify a list of IP addresses or hostnames of NTP pools to synchronize to. @item @code{constraint-from} (default: @code{'()}) @code{ntpd} can be configured to query the ‘Date’ from trusted HTTPS servers via TLS. This time information is not used for precision but acts as an authenticated constraint, thereby reducing the impact of unauthenticated NTP man-in-the-middle attacks. Specify a list of URLs, IP addresses or hostnames of HTTPS servers to provide a constraint. @item @code{constraints-from} (default: @code{'()}) As with constraint from, specify a list of URLs, IP addresses or hostnames of HTTPS servers to provide a constraint. Should the hostname resolve to multiple IP addresses, @code{ntpd} will calculate a median constraint from all of them. @item @code{allow-large-adjustment?} (default: @code{#f}) Determines if @code{ntpd} is allowed to make an initial adjustment of more than 180 seconds. @end table @end deftp @cindex inetd @deffn {Scheme variable} inetd-service-type This service runs the @command{inetd} (@pxref{inetd invocation,,, inetutils, GNU Inetutils}) daemon. @command{inetd} listens for connections on internet sockets, and lazily starts the specified server program when a connection is made on one of these sockets. The value of this service is an @code{inetd-configuration} object. The following example configures the @command{inetd} daemon to provide the built-in @command{echo} service, as well as an smtp service which forwards smtp traffic over ssh to a server @code{smtp-server} behind a gateway @code{hostname}: @lisp (service inetd-service-type (inetd-configuration (entries (list (inetd-entry (name "echo") (socket-type 'stream) (protocol "tcp") (wait? #f) (user "root")) (inetd-entry (node "127.0.0.1") (name "smtp") (socket-type 'stream) (protocol "tcp") (wait? #f) (user "root") (program (file-append openssh "/bin/ssh")) (arguments '("ssh" "-qT" "-i" "/path/to/ssh_key" "-W" "smtp-server:25" "user@@hostname"))))))) @end lisp See below for more details about @code{inetd-configuration}. @end deffn @deftp {Data Type} inetd-configuration Data type representing the configuration of @command{inetd}. @table @asis @item @code{program} (default: @code{(file-append inetutils "/libexec/inetd")}) The @command{inetd} executable to use. @item @code{entries} (default: @code{'()}) A list of @command{inetd} service entries. Each entry should be created by the @code{inetd-entry} constructor. @end table @end deftp @deftp {Data Type} inetd-entry Data type representing an entry in the @command{inetd} configuration. Each entry corresponds to a socket where @command{inetd} will listen for requests. @table @asis @item @code{node} (default: @code{#f}) Optional string, a comma-separated list of local addresses @command{inetd} should use when listening for this service. @xref{Configuration file,,, inetutils, GNU Inetutils} for a complete description of all options. @item @code{name} A string, the name must correspond to an entry in @code{/etc/services}. @item @code{socket-type} One of @code{'stream}, @code{'dgram}, @code{'raw}, @code{'rdm} or @code{'seqpacket}. @item @code{protocol} A string, must correspond to an entry in @code{/etc/protocols}. @item @code{wait?} (default: @code{#t}) Whether @command{inetd} should wait for the server to exit before listening to new service requests. @item @code{user} A string containing the user (and, optionally, group) name of the user as whom the server should run. The group name can be specified in a suffix, separated by a colon or period, i.e.@: @code{"user"}, @code{"user:group"} or @code{"user.group"}. @item @code{program} (default: @code{"internal"}) The server program which will serve the requests, or @code{"internal"} if @command{inetd} should use a built-in service. @item @code{arguments} (default: @code{'()}) A list strings or file-like objects, which are the server program's arguments, starting with the zeroth argument, i.e.@: the name of the program itself. For @command{inetd}'s internal services, this entry must be @code{'()} or @code{'("internal")}. @end table @xref{Configuration file,,, inetutils, GNU Inetutils} for a more detailed discussion of each configuration field. @end deftp @cindex Tor @defvr {Scheme Variable} tor-service-type This is the type for a service that runs the @uref{https://torproject.org, Tor} anonymous networking daemon. The service is configured using a @code{} record. By default, the Tor daemon runs as the @code{tor} unprivileged user, which is a member of the @code{tor} group. @end defvr @deftp {Data Type} tor-configuration @table @asis @item @code{tor} (default: @code{tor}) The package that provides the Tor daemon. This package is expected to provide the daemon at @file{bin/tor} relative to its output directory. The default package is the @uref{https://www.torproject.org, Tor Project's} implementation. @item @code{config-file} (default: @code{(plain-file "empty" "")}) The configuration file to use. It will be appended to a default configuration file, and the final configuration file will be passed to @code{tor} via its @code{-f} option. This may be any ``file-like'' object (@pxref{G-Expressions, file-like objects}). See @code{man tor} for details on the configuration file syntax. @item @code{hidden-services} (default: @code{'()}) The list of @code{} records to use. For any hidden service you include in this list, appropriate configuration to enable the hidden service will be automatically added to the default configuration file. You may conveniently create @code{} records using the @code{tor-hidden-service} procedure described below. @item @code{socks-socket-type} (default: @code{'tcp}) The default socket type that Tor should use for its SOCKS socket. This must be either @code{'tcp} or @code{'unix}. If it is @code{'tcp}, then by default Tor will listen on TCP port 9050 on the loopback interface (i.e., localhost). If it is @code{'unix}, then Tor will listen on the UNIX domain socket @file{/var/run/tor/socks-sock}, which will be made writable by members of the @code{tor} group. If you want to customize the SOCKS socket in more detail, leave @code{socks-socket-type} at its default value of @code{'tcp} and use @code{config-file} to override the default by providing your own @code{SocksPort} option. @end table @end deftp @cindex hidden service @deffn {Scheme Procedure} tor-hidden-service @var{name} @var{mapping} Define a new Tor @dfn{hidden service} called @var{name} and implementing @var{mapping}. @var{mapping} is a list of port/host tuples, such as: @example '((22 "127.0.0.1:22") (80 "127.0.0.1:8080")) @end example In this example, port 22 of the hidden service is mapped to local port 22, and port 80 is mapped to local port 8080. This creates a @file{/var/lib/tor/hidden-services/@var{name}} directory, where the @file{hostname} file contains the @code{.onion} host name for the hidden service. See @uref{https://www.torproject.org/docs/tor-hidden-service.html.en, the Tor project's documentation} for more information. @end deffn The @code{(gnu services rsync)} module provides the following services: You might want an rsync daemon if you have files that you want available so anyone (or just yourself) can download existing files or upload new files. @deffn {Scheme Variable} rsync-service-type This is the service type for the @uref{https://rsync.samba.org, rsync} daemon, The value for this service type is a @command{rsync-configuration} record as in this example: @lisp (service rsync-service-type) @end lisp See below for details about @code{rsync-configuration}. @end deffn @deftp {Data Type} rsync-configuration Data type representing the configuration for @code{rsync-service}. @table @asis @item @code{package} (default: @var{rsync}) @code{rsync} package to use. @item @code{port-number} (default: @code{873}) TCP port on which @command{rsync} listens for incoming connections. If port is less than @code{1024} @command{rsync} needs to be started as the @code{root} user and group. @item @code{pid-file} (default: @code{"/var/run/rsyncd/rsyncd.pid"}) Name of the file where @command{rsync} writes its PID. @item @code{lock-file} (default: @code{"/var/run/rsyncd/rsyncd.lock"}) Name of the file where @command{rsync} writes its lock file. @item @code{log-file} (default: @code{"/var/log/rsyncd.log"}) Name of the file where @command{rsync} writes its log file. @item @code{use-chroot?} (default: @var{#t}) Whether to use chroot for @command{rsync} shared directory. @item @code{share-path} (default: @file{/srv/rsync}) Location of the @command{rsync} shared directory. @item @code{share-comment} (default: @code{"Rsync share"}) Comment of the @command{rsync} shared directory. @item @code{read-only?} (default: @var{#f}) Read-write permissions to shared directory. @item @code{timeout} (default: @code{300}) I/O timeout in seconds. @item @code{user} (default: @var{"root"}) Owner of the @code{rsync} process. @item @code{group} (default: @var{"root"}) Group of the @code{rsync} process. @item @code{uid} (default: @var{"rsyncd"}) User name or user ID that file transfers to and from that module should take place as when the daemon was run as @code{root}. @item @code{gid} (default: @var{"rsyncd"}) Group name or group ID that will be used when accessing the module. @end table @end deftp The @code{(gnu services syncthing)} module provides the following services: @cindex syncthing You might want a syncthing daemon if you have files between two or more computers and want to sync them in real time, safely protected from prying eyes. @deffn {Scheme Variable} syncthing-service-type This is the service type for the @uref{https://syncthing.net/, syncthing} daemon, The value for this service type is a @command{syncthing-configuration} record as in this example: @lisp (service syncthing-service-type (syncthing-configuration (user "alice"))) @end lisp See below for details about @code{syncthing-configuration}. @deftp {Data Type} syncthing-configuration Data type representing the configuration for @code{syncthing-service-type}. @table @asis @item @code{syncthing} (default: @var{syncthing}) @code{syncthing} package to use. @item @code{arguments} (default: @var{'()}) List of command-line arguments passing to @code{syncthing} binary. @item @code{logflags} (default: @var{0}) Sum of loging flags, see @uref{https://docs.syncthing.net/users/syncthing.html#cmdoption-logflags, Syncthing documentation logflags}. @item @code{user} (default: @var{#f}) The user as which the Syncthing service is to be run. This assumes that the specified user exists. @item @code{group} (default: @var{"users"}) The group as which the Syncthing service is to be run. This assumes that the specified group exists. @item @code{home} (default: @var{#f}) Common configuration and data directory. The default configuration directory is @file{$HOME} of the specified Syncthing @code{user}. @end table @end deftp @end deffn Furthermore, @code{(gnu services ssh)} provides the following services. @cindex SSH @cindex SSH server @deffn {Scheme Procedure} lsh-service [#:host-key "/etc/lsh/host-key"] @ [#:daemonic? #t] [#:interfaces '()] [#:port-number 22] @ [#:allow-empty-passwords? #f] [#:root-login? #f] @ [#:syslog-output? #t] [#:x11-forwarding? #t] @ [#:tcp/ip-forwarding? #t] [#:password-authentication? #t] @ [#:public-key-authentication? #t] [#:initialize? #t] Run the @command{lshd} program from @var{lsh} to listen on port @var{port-number}. @var{host-key} must designate a file containing the host key, and readable only by root. When @var{daemonic?} is true, @command{lshd} will detach from the controlling terminal and log its output to syslogd, unless one sets @var{syslog-output?} to false. Obviously, it also makes lsh-service depend on existence of syslogd service. When @var{pid-file?} is true, @command{lshd} writes its PID to the file called @var{pid-file}. When @var{initialize?} is true, automatically create the seed and host key upon service activation if they do not exist yet. This may take long and require interaction. When @var{initialize?} is false, it is up to the user to initialize the randomness generator (@pxref{lsh-make-seed,,, lsh, LSH Manual}), and to create a key pair with the private key stored in file @var{host-key} (@pxref{lshd basics,,, lsh, LSH Manual}). When @var{interfaces} is empty, lshd listens for connections on all the network interfaces; otherwise, @var{interfaces} must be a list of host names or addresses. @var{allow-empty-passwords?} specifies whether to accept log-ins with empty passwords, and @var{root-login?} specifies whether to accept log-ins as root. The other options should be self-descriptive. @end deffn @cindex SSH @cindex SSH server @deffn {Scheme Variable} openssh-service-type This is the type for the @uref{http://www.openssh.org, OpenSSH} secure shell daemon, @command{sshd}. Its value must be an @code{openssh-configuration} record as in this example: @lisp (service openssh-service-type (openssh-configuration (x11-forwarding? #t) (permit-root-login 'without-password) (authorized-keys `(("alice" ,(local-file "alice.pub")) ("bob" ,(local-file "bob.pub")))))) @end lisp See below for details about @code{openssh-configuration}. This service can be extended with extra authorized keys, as in this example: @lisp (service-extension openssh-service-type (const `(("charlie" ,(local-file "charlie.pub"))))) @end lisp @end deffn @deftp {Data Type} openssh-configuration This is the configuration record for OpenSSH's @command{sshd}. @table @asis @item @code{openssh} (default @var{openssh}) The Openssh package to use. @item @code{pid-file} (default: @code{"/var/run/sshd.pid"}) Name of the file where @command{sshd} writes its PID. @item @code{port-number} (default: @code{22}) TCP port on which @command{sshd} listens for incoming connections. @item @code{permit-root-login} (default: @code{#f}) This field determines whether and when to allow logins as root. If @code{#f}, root logins are disallowed; if @code{#t}, they are allowed. If it's the symbol @code{'without-password}, then root logins are permitted but not with password-based authentication. @item @code{allow-empty-passwords?} (default: @code{#f}) When true, users with empty passwords may log in. When false, they may not. @item @code{password-authentication?} (default: @code{#t}) When true, users may log in with their password. When false, they have other authentication methods. @item @code{public-key-authentication?} (default: @code{#t}) When true, users may log in using public key authentication. When false, users have to use other authentication method. Authorized public keys are stored in @file{~/.ssh/authorized_keys}. This is used only by protocol version 2. @item @code{x11-forwarding?} (default: @code{#f}) When true, forwarding of X11 graphical client connections is enabled---in other words, @command{ssh} options @option{-X} and @option{-Y} will work. @item @code{allow-agent-forwarding?} (default: @code{#t}) Whether to allow agent forwarding. @item @code{allow-tcp-forwarding?} (default: @code{#t}) Whether to allow TCP forwarding. @item @code{gateway-ports?} (default: @code{#f}) Whether to allow gateway ports. @item @code{challenge-response-authentication?} (default: @code{#f}) Specifies whether challenge response authentication is allowed (e.g.@: via PAM). @item @code{use-pam?} (default: @code{#t}) Enables the Pluggable Authentication Module interface. If set to @code{#t}, this will enable PAM authentication using @code{challenge-response-authentication?} and @code{password-authentication?}, in addition to PAM account and session module processing for all authentication types. Because PAM challenge response authentication usually serves an equivalent role to password authentication, you should disable either @code{challenge-response-authentication?} or @code{password-authentication?}. @item @code{print-last-log?} (default: @code{#t}) Specifies whether @command{sshd} should print the date and time of the last user login when a user logs in interactively. @item @code{subsystems} (default: @code{'(("sftp" "internal-sftp"))}) Configures external subsystems (e.g.@: file transfer daemon). This is a list of two-element lists, each of which containing the subsystem name and a command (with optional arguments) to execute upon subsystem request. The command @command{internal-sftp} implements an in-process SFTP server. Alternatively, one can specify the @command{sftp-server} command: @lisp (service openssh-service-type (openssh-configuration (subsystems `(("sftp" ,(file-append openssh "/libexec/sftp-server")))))) @end lisp @item @code{accepted-environment} (default: @code{'()}) List of strings describing which environment variables may be exported. Each string gets on its own line. See the @code{AcceptEnv} option in @code{man sshd_config}. This example allows ssh-clients to export the @env{COLORTERM} variable. It is set by terminal emulators, which support colors. You can use it in your shell's resource file to enable colors for the prompt and commands if this variable is set. @lisp (service openssh-service-type (openssh-configuration (accepted-environment '("COLORTERM")))) @end lisp @item @code{authorized-keys} (default: @code{'()}) @cindex authorized keys, SSH @cindex SSH authorized keys This is the list of authorized keys. Each element of the list is a user name followed by one or more file-like objects that represent SSH public keys. For example: @lisp (openssh-configuration (authorized-keys `(("rekado" ,(local-file "rekado.pub")) ("chris" ,(local-file "chris.pub")) ("root" ,(local-file "rekado.pub") ,(local-file "chris.pub"))))) @end lisp @noindent registers the specified public keys for user accounts @code{rekado}, @code{chris}, and @code{root}. Additional authorized keys can be specified @i{via} @code{service-extension}. Note that this does @emph{not} interfere with the use of @file{~/.ssh/authorized_keys}. @item @code{log-level} (default: @code{'info}) This is a symbol specifying the logging level: @code{quiet}, @code{fatal}, @code{error}, @code{info}, @code{verbose}, @code{debug}, etc. See the man page for @file{sshd_config} for the full list of level names. @item @code{extra-content} (default: @code{""}) This field can be used to append arbitrary text to the configuration file. It is especially useful for elaborate configurations that cannot be expressed otherwise. This configuration, for example, would generally disable root logins, but permit them from one specific IP address: @lisp (openssh-configuration (extra-content "\ Match Address 192.168.0.1 PermitRootLogin yes")) @end lisp @end table @end deftp @deffn {Scheme Procedure} dropbear-service [@var{config}] Run the @uref{https://matt.ucc.asn.au/dropbear/dropbear.html,Dropbear SSH daemon} with the given @var{config}, a @code{} object. For example, to specify a Dropbear service listening on port 1234, add this call to the operating system's @code{services} field: @lisp (dropbear-service (dropbear-configuration (port-number 1234))) @end lisp @end deffn @deftp {Data Type} dropbear-configuration This data type represents the configuration of a Dropbear SSH daemon. @table @asis @item @code{dropbear} (default: @var{dropbear}) The Dropbear package to use. @item @code{port-number} (default: 22) The TCP port where the daemon waits for incoming connections. @item @code{syslog-output?} (default: @code{#t}) Whether to enable syslog output. @item @code{pid-file} (default: @code{"/var/run/dropbear.pid"}) File name of the daemon's PID file. @item @code{root-login?} (default: @code{#f}) Whether to allow @code{root} logins. @item @code{allow-empty-passwords?} (default: @code{#f}) Whether to allow empty passwords. @item @code{password-authentication?} (default: @code{#t}) Whether to enable password-based authentication. @end table @end deftp @cindex AutoSSH @deffn {Scheme Variable} autossh-service-type This is the type for the @uref{https://www.harding.motd.ca/autossh, AutoSSH} program that runs a copy of @command{ssh} and monitors it, restarting it as necessary should it die or stop passing traffic. AutoSSH can be run manually from the command-line by passing arguments to the binary @command{autossh} from the package @code{autossh}, but it can also be run as a Guix service. This latter use case is documented here. AutoSSH can be used to forward local traffic to a remote machine using an SSH tunnel, and it respects the @file{~/.ssh/config} of the user it is run as. For example, to specify a service running autossh as the user @code{pino} and forwarding all local connections to port @code{8081} to @code{remote:8081} using an SSH tunnel, add this call to the operating system's @code{services} field: @lisp (service autossh-service-type (autossh-configuration (user "pino") (ssh-options (list "-T" "-N" "-L" "8081:localhost:8081" "remote.net")))) @end lisp @end deffn @deftp {Data Type} autossh-configuration This data type represents the configuration of an AutoSSH service. @table @asis @item @code{user} (default @code{"autossh"}) The user as which the AutoSSH service is to be run. This assumes that the specified user exists. @item @code{poll} (default @code{600}) Specifies the connection poll time in seconds. @item @code{first-poll} (default @code{#f}) Specifies how many seconds AutoSSH waits before the first connection test. After this first test, polling is resumed at the pace defined in @code{poll}. When set to @code{#f}, the first poll is not treated specially and will also use the connection poll specified in @code{poll}. @item @code{gate-time} (default @code{30}) Specifies how many seconds an SSH connection must be active before it is considered successful. @item @code{log-level} (default @code{1}) The log level, corresponding to the levels used by syslog---so @code{0} is the most silent while @code{7} is the chattiest. @item @code{max-start} (default @code{#f}) The maximum number of times SSH may be (re)started before AutoSSH exits. When set to @code{#f}, no maximum is configured and AutoSSH may restart indefinitely. @item @code{message} (default @code{""}) The message to append to the echo message sent when testing connections. @item @code{port} (default @code{"0"}) The ports used for monitoring the connection. When set to @code{"0"}, monitoring is disabled. When set to @code{"@var{n}"} where @var{n} is a positive integer, ports @var{n} and @var{n}+1 are used for monitoring the connection, such that port @var{n} is the base monitoring port and @code{n+1} is the echo port. When set to @code{"@var{n}:@var{m}"} where @var{n} and @var{m} are positive integers, the ports @var{n} and @var{m} are used for monitoring the connection, such that port @var{n} is the base monitoring port and @var{m} is the echo port. @item @code{ssh-options} (default @code{'()}) The list of command-line arguments to pass to @command{ssh} when it is run. Options @option{-f} and @option{-M} are reserved for AutoSSH and may cause undefined behaviour. @end table @end deftp @cindex WebSSH @deffn {Scheme Variable} webssh-service-type This is the type for the @uref{https://webssh.huashengdun.org/, WebSSH} program that runs a web SSH client. WebSSH can be run manually from the command-line by passing arguments to the binary @command{wssh} from the package @code{webssh}, but it can also be run as a Guix service. This latter use case is documented here. For example, to specify a service running WebSSH on loopback interface on port @code{8888} with reject policy with a list of allowed to connection hosts, and NGINX as a reverse-proxy to this service listening for HTTPS connection, add this call to the operating system's @code{services} field: @lisp (service webssh-service-type (webssh-configuration (address "127.0.0.1") (port 8888) (policy 'reject) (known-hosts '("localhost ecdsa-sha2-nistp256 AAAA…" "127.0.0.1 ecdsa-sha2-nistp256 AAAA…")))) (service nginx-service-type (nginx-configuration (server-blocks (list (nginx-server-configuration (inherit %webssh-configuration-nginx) (server-name '("webssh.example.com")) (listen '("443 ssl")) (ssl-certificate (letsencrypt-certificate "webssh.example.com")) (ssl-certificate-key (letsencrypt-key "webssh.example.com")) (locations (cons (nginx-location-configuration (uri "/.well-known") (body '("root /var/www;"))) (nginx-server-configuration-locations %webssh-configuration-nginx)))))))) @end lisp @end deffn @deftp {Data Type} webssh-configuration Data type representing the configuration for @code{webssh-service}. @table @asis @item @code{package} (default: @var{webssh}) @code{webssh} package to use. @item @code{user-name} (default: @var{"webssh"}) User name or user ID that file transfers to and from that module should take place. @item @code{group-name} (default: @var{"webssh"}) Group name or group ID that will be used when accessing the module. @item @code{address} (default: @var{#f}) IP address on which @command{webssh} listens for incoming connections. @item @code{port} (default: @var{8888}) TCP port on which @command{webssh} listens for incoming connections. @item @code{policy} (default: @var{#f}) Connection policy. @var{reject} policy requires to specify @var{known-hosts}. @item @code{known-hosts} (default: @var{'()}) List of hosts which allowed for SSH connection from @command{webssh}. @item @code{log-file} (default: @file{"/var/log/webssh.log"}) Name of the file where @command{webssh} writes its log file. @item @code{log-level} (default: @var{#f}) Logging level. @end table @end deftp @defvr {Scheme Variable} %facebook-host-aliases This variable contains a string for use in @file{/etc/hosts} (@pxref{Host Names,,, libc, The GNU C Library Reference Manual}). Each line contains a entry that maps a known server name of the Facebook on-line service---e.g., @code{www.facebook.com}---to the local host---@code{127.0.0.1} or its IPv6 equivalent, @code{::1}. This variable is typically used in the @code{hosts-file} field of an @code{operating-system} declaration (@pxref{operating-system Reference, @file{/etc/hosts}}): @lisp (use-modules (gnu) (guix)) (operating-system (host-name "mymachine") ;; ... (hosts-file ;; Create a /etc/hosts file with aliases for "localhost" ;; and "mymachine", as well as for Facebook servers. (plain-file "hosts" (string-append (local-host-aliases host-name) %facebook-host-aliases)))) @end lisp This mechanism can prevent programs running locally, such as Web browsers, from accessing Facebook. @end defvr The @code{(gnu services avahi)} provides the following definition. @defvr {Scheme Variable} avahi-service-type This is the service that runs @command{avahi-daemon}, a system-wide mDNS/DNS-SD responder that allows for service discovery and ``zero-configuration'' host name lookups (see @uref{https://avahi.org/}). Its value must be an @code{avahi-configuration} record---see below. This service extends the name service cache daemon (nscd) so that it can resolve @code{.local} host names using @uref{https://0pointer.de/lennart/projects/nss-mdns/, nss-mdns}. @xref{Name Service Switch}, for information on host name resolution. Additionally, add the @var{avahi} package to the system profile so that commands such as @command{avahi-browse} are directly usable. @end defvr @deftp {Data Type} avahi-configuration Data type representation the configuration for Avahi. @table @asis @item @code{host-name} (default: @code{#f}) If different from @code{#f}, use that as the host name to publish for this machine; otherwise, use the machine's actual host name. @item @code{publish?} (default: @code{#t}) When true, allow host names and services to be published (broadcast) over the network. @item @code{publish-workstation?} (default: @code{#t}) When true, @command{avahi-daemon} publishes the machine's host name and IP address via mDNS on the local network. To view the host names published on your local network, you can run: @example avahi-browse _workstation._tcp @end example @item @code{wide-area?} (default: @code{#f}) When true, DNS-SD over unicast DNS is enabled. @item @code{ipv4?} (default: @code{#t}) @itemx @code{ipv6?} (default: @code{#t}) These fields determine whether to use IPv4/IPv6 sockets. @item @code{domains-to-browse} (default: @code{'()}) This is a list of domains to browse. @end table @end deftp @deffn {Scheme Variable} openvswitch-service-type This is the type of the @uref{https://www.openvswitch.org, Open vSwitch} service, whose value should be an @code{openvswitch-configuration} object. @end deffn @deftp {Data Type} openvswitch-configuration Data type representing the configuration of Open vSwitch, a multilayer virtual switch which is designed to enable massive network automation through programmatic extension. @table @asis @item @code{package} (default: @var{openvswitch}) Package object of the Open vSwitch. @end table @end deftp @defvr {Scheme Variable} pagekite-service-type This is the service type for the @uref{https://pagekite.net, PageKite} service, a tunneling solution for making localhost servers publicly visible, even from behind restrictive firewalls or NAT without forwarded ports. The value for this service type is a @code{pagekite-configuration} record. Here's an example exposing the local HTTP and SSH daemons: @lisp (service pagekite-service-type (pagekite-configuration (kites '("http:@@kitename:localhost:80:@@kitesecret" "raw/22:@@kitename:localhost:22:@@kitesecret")) (extra-file "/etc/pagekite.rc"))) @end lisp @end defvr @deftp {Data Type} pagekite-configuration Data type representing the configuration of PageKite. @table @asis @item @code{package} (default: @var{pagekite}) Package object of PageKite. @item @code{kitename} (default: @code{#f}) PageKite name for authenticating to the frontend server. @item @code{kitesecret} (default: @code{#f}) Shared secret for authenticating to the frontend server. You should probably put this inside @code{extra-file} instead. @item @code{frontend} (default: @code{#f}) Connect to the named PageKite frontend server instead of the @uref{https://pagekite.net,,pagekite.net} service. @item @code{kites} (default: @code{'("http:@@kitename:localhost:80:@@kitesecret")}) List of service kites to use. Exposes HTTP on port 80 by default. The format is @code{proto:kitename:host:port:secret}. @item @code{extra-file} (default: @code{#f}) Extra configuration file to read, which you are expected to create manually. Use this to add additional options and manage shared secrets out-of-band. @end table @end deftp @defvr {Scheme Variable} yggdrasil-service-type The service type for connecting to the @uref{https://yggdrasil-network.github.io/, Yggdrasil network}, an early-stage implementation of a fully end-to-end encrypted IPv6 network. @quotation Yggdrasil provides name-independent routing with cryptographically generated addresses. Static addressing means you can keep the same address as long as you want, even if you move to a new location, or generate a new address (by generating new keys) whenever you want. @uref{https://yggdrasil-network.github.io/2018/07/28/addressing.html} @end quotation Pass it a value of @code{yggdrasil-configuration} to connect it to public peers and/or local peers. Here is an example using public peers and a static address. The static signing and encryption keys are defined in @file{/etc/yggdrasil-private.conf} (the default value for @code{config-file}). @lisp ;; part of the operating-system declaration (service yggdrasil-service-type (yggdrasil-configuration (autoconf? #f) ;; use only the public peers (json-config ;; choose one from ;; https://github.com/yggdrasil-network/public-peers '((peers . #("tcp://1.2.3.4:1337")))) ;; /etc/yggdrasil-private.conf is the default value for config-file )) @end lisp @example # sample content for /etc/yggdrasil-private.conf @{ # Your public encryption key. Your peers may ask you for this to put # into their AllowedEncryptionPublicKeys configuration. EncryptionPublicKey: 378dc5... # Your private encryption key. DO NOT share this with anyone! EncryptionPrivateKey: 0777... # Your public signing key. You should not ordinarily need to share # this with anyone. SigningPublicKey: e1664... # Your private signing key. DO NOT share this with anyone! SigningPrivateKey: 0589d... @} @end example @end defvr @deftp {Data Type} yggdrasil-configuration Data type representing the configuration of Yggdrasil. @table @asis @item @code{package} (default: @code{yggdrasil}) Package object of Yggdrasil. @item @code{json-config} (default: @code{'()}) Contents of @file{/etc/yggdrasil.conf}. Will be merged with @file{/etc/yggdrasil-private.conf}. Note that these settings are stored in the Guix store, which is readable to all users. @strong{Do not store your private keys in it}. See the output of @code{yggdrasil -genconf} for a quick overview of valid keys and their default values. @item @code{autoconf?} (default: @code{#f}) Whether to use automatic mode. Enabling it makes Yggdrasil use adynamic IP and peer with IPv6 neighbors. @item @code{log-level} (default: @code{'info}) How much detail to include in logs. Use @code{'debug} for more detail. @item @code{log-to} (default: @code{'stdout}) Where to send logs. By default, the service logs standard output to @file{/var/log/yggdrasil.log}. The alternative is @code{'syslog}, which sends output to the running syslog service. @item @code{config-file} (default: @code{"/etc/yggdrasil-private.conf"}) What HJSON file to load sensitive data from. This is where private keys should be stored, which are necessary to specify if you don't want a randomized address after each restart. Use @code{#f} to disable. Options defined in this file take precedence over @code{json-config}. Use the output of @code{yggdrasil -genconf} as a starting point. To configure a static address, delete everything except these options: @itemize @item @code{EncryptionPublicKey} @item @code{EncryptionPrivateKey} @item @code{SigningPublicKey} @item @code{SigningPrivateKey} @end itemize @end table @end deftp @cindex keepalived @deffn {Scheme Variable} keepalived-service-type This is the type for the @uref{https://www.keepalived.org/, Keepalived} routing software, @command{keepalived}. Its value must be an @code{keepalived-configuration} record as in this example for master machine: @lisp (service keepalived-service-type (keepalived-configuration (config-file (local-file "keepalived-master.conf")))) @end lisp where @file{keepalived-master.conf}: @example vrrp_instance my-group @{ state MASTER interface enp9s0 virtual_router_id 100 priority 100 unicast_peer @{ 10.0.0.2 @} virtual_ipaddress @{ 10.0.0.4/24 @} @} @end example and for backup machine: @lisp (service keepalived-service-type (keepalived-configuration (config-file (local-file "keepalived-backup.conf")))) @end lisp where @file{keepalived-backup.conf}: @example vrrp_instance my-group @{ state BACKUP interface enp9s0 virtual_router_id 100 priority 99 unicast_peer @{ 10.0.0.3 @} virtual_ipaddress @{ 10.0.0.4/24 @} @} @end example @end deffn @node Unattended Upgrades @subsection Unattended Upgrades @cindex unattended upgrades @cindex upgrades, unattended Guix provides a service to perform @emph{unattended upgrades}: periodically, the system automatically reconfigures itself from the latest Guix. Guix System has several properties that make unattended upgrades safe: @itemize @item upgrades are transactional (either the upgrade succeeds or it fails, but you cannot end up with an ``in-between'' system state); @item the upgrade log is kept---you can view it with @command{guix system list-generations}---and you can roll back to any previous generation, should the upgraded system fail to behave as intended; @item channel code is authenticated so you know you can only run genuine code (@pxref{Channels}); @item @command{guix system reconfigure} prevents downgrades, which makes it immune to @dfn{downgrade attacks}. @end itemize To set up unattended upgrades, add an instance of @code{unattended-upgrade-service-type} like the one below to the list of your operating system services: @lisp (service unattended-upgrade-service-type) @end lisp The defaults above set up weekly upgrades: every Sunday at midnight. You do not need to provide the operating system configuration file: it uses @file{/run/current-system/configuration.scm}, which ensures it always uses your latest configuration---@pxref{provenance-service-type}, for more information about this file. There are several things that can be configured, in particular the periodicity and services (daemons) to be restarted upon completion. When the upgrade is successful, the service takes care of deleting system generations older that some threshold, as per @command{guix system delete-generations}. See the reference below for details. To ensure that upgrades are actually happening, you can run @command{guix system describe}. To investigate upgrade failures, visit the unattended upgrade log file (see below). @defvr {Scheme Variable} unattended-upgrade-service-type This is the service type for unattended upgrades. It sets up an mcron job (@pxref{Scheduled Job Execution}) that runs @command{guix system reconfigure} from the latest version of the specified channels. Its value must be a @code{unattended-upgrade-configuration} record (see below). @end defvr @deftp {Data Type} unattended-upgrade-configuration This data type represents the configuration of the unattended upgrade service. The following fields are available: @table @asis @item @code{schedule} (default: @code{"30 01 * * 0"}) This is the schedule of upgrades, expressed as a gexp containing an mcron job schedule (@pxref{Guile Syntax, mcron job specifications,, mcron, GNU@tie{}mcron}). @item @code{channels} (default: @code{#~%default-channels}) This gexp specifies the channels to use for the upgrade (@pxref{Channels}). By default, the tip of the official @code{guix} channel is used. @item @code{operating-system-file} (default: @code{"/run/current-system/configuration.scm"}) This field specifies the operating system configuration file to use. The default is to reuse the config file of the current configuration. There are cases, though, where referring to @file{/run/current-system/configuration.scm} is not enough, for instance because that file refers to extra files (SSH public keys, extra configuration files, etc.) @i{via} @code{local-file} and similar constructs. For those cases, we recommend something along these lines: @lisp (unattended-upgrade-configuration (operating-system-file (file-append (local-file "." "config-dir" #:recursive? #t) "/config.scm"))) @end lisp The effect here is to import all of the current directory into the store, and to refer to @file{config.scm} within that directory. Therefore, uses of @code{local-file} within @file{config.scm} will work as expected. @xref{G-Expressions}, for information about @code{local-file} and @code{file-append}. @item @code{services-to-restart} (default: @code{'(mcron)}) This field specifies the Shepherd services to restart when the upgrade completes. Those services are restarted right away upon completion, as with @command{herd restart}, which ensures that the latest version is running---remember that by default @command{guix system reconfigure} only restarts services that are not currently running, which is conservative: it minimizes disruption but leaves outdated services running. Use @command{herd status} to find out candidates for restarting. @xref{Services}, for general information about services. Common services to restart would include @code{ntpd} and @code{ssh-daemon}. By default, the @code{mcron} service is restarted. This ensures that the latest version of the unattended upgrade job will be used next time. @item @code{system-expiration} (default: @code{(* 3 30 24 3600)}) This is the expiration time in seconds for system generations. System generations older that this amount of time are deleted with @command{guix system delete-generations} when an upgrade completes. @quotation Note The unattended upgrade service does not run the garbage collector. You will probably want to set up your own mcron job to run @command{guix gc} periodically. @end quotation @item @code{maximum-duration} (default: @code{3600}) Maximum duration in seconds for the upgrade; past that time, the upgrade aborts. This is primarily useful to ensure the upgrade does not end up rebuilding or re-downloading ``the world''. @item @code{log-file} (default: @code{"/var/log/unattended-upgrade.log"}) File where unattended upgrades are logged. @end table @end deftp @node X Window @subsection X Window @cindex X11 @cindex X Window System @cindex login manager Support for the X Window graphical display system---specifically Xorg---is provided by the @code{(gnu services xorg)} module. Note that there is no @code{xorg-service} procedure. Instead, the X server is started by the @dfn{login manager}, by default the GNOME Display Manager (GDM). @cindex GDM @cindex GNOME, login manager GDM of course allows users to log in into window managers and desktop environments other than GNOME; for those using GNOME, GDM is required for features such as automatic screen locking. @cindex window manager To use X11, you must install at least one @dfn{window manager}---for example the @code{windowmaker} or @code{openbox} packages---preferably by adding it to the @code{packages} field of your operating system definition (@pxref{operating-system Reference, system-wide packages}). @defvr {Scheme Variable} gdm-service-type This is the type for the @uref{https://wiki.gnome.org/Projects/GDM/, GNOME Desktop Manager} (GDM), a program that manages graphical display servers and handles graphical user logins. Its value must be a @code{gdm-configuration} (see below). @cindex session types (X11) @cindex X11 session types GDM looks for @dfn{session types} described by the @file{.desktop} files in @file{/run/current-system/profile/share/xsessions} and allows users to choose a session from the log-in screen. Packages such as @code{gnome}, @code{xfce}, and @code{i3} provide @file{.desktop} files; adding them to the system-wide set of packages automatically makes them available at the log-in screen. In addition, @file{~/.xsession} files are honored. When available, @file{~/.xsession} must be an executable that starts a window manager and/or other X clients. @end defvr @deftp {Data Type} gdm-configuration @table @asis @item @code{auto-login?} (default: @code{#f}) @itemx @code{default-user} (default: @code{#f}) When @code{auto-login?} is false, GDM presents a log-in screen. When @code{auto-login?} is true, GDM logs in directly as @code{default-user}. @item @code{debug?} (default: @code{#f}) When true, GDM writes debug messages to its log. @item @code{gnome-shell-assets} (default: ...) List of GNOME Shell assets needed by GDM: icon theme, fonts, etc. @item @code{xorg-configuration} (default: @code{(xorg-configuration)}) Configuration of the Xorg graphical server. @item @code{xsession} (default: @code{(xinitrc)}) Script to run before starting a X session. @item @code{dbus-daemon} (default: @code{dbus-daemon-wrapper}) File name of the @code{dbus-daemon} executable. @item @code{gdm} (default: @code{gdm}) The GDM package to use. @end table @end deftp @defvr {Scheme Variable} slim-service-type This is the type for the SLiM graphical login manager for X11. Like GDM, SLiM looks for session types described by @file{.desktop} files and allows users to choose a session from the log-in screen using @kbd{F1}. It also honors @file{~/.xsession} files. Unlike GDM, SLiM does not spawn the user session on a different VT after logging in, which means that you can only start one graphical session. If you want to be able to run multiple graphical sessions at the same time you have to add multiple SLiM services to your system services. The following example shows how to replace the default GDM service with two SLiM services on tty7 and tty8. @lisp (use-modules (gnu services) (gnu services desktop) (gnu services xorg) (srfi srfi-1)) ;for 'remove' (operating-system ;; ... (services (cons* (service slim-service-type (slim-configuration (display ":0") (vt "vt7"))) (service slim-service-type (slim-configuration (display ":1") (vt "vt8"))) (remove (lambda (service) (eq? (service-kind service) gdm-service-type)) %desktop-services)))) @end lisp @end defvr @deftp {Data Type} slim-configuration Data type representing the configuration of @code{slim-service-type}. @table @asis @item @code{allow-empty-passwords?} (default: @code{#t}) Whether to allow logins with empty passwords. @item @code{auto-login?} (default: @code{#f}) @itemx @code{default-user} (default: @code{""}) When @code{auto-login?} is false, SLiM presents a log-in screen. When @code{auto-login?} is true, SLiM logs in directly as @code{default-user}. @item @code{theme} (default: @code{%default-slim-theme}) @itemx @code{theme-name} (default: @code{%default-slim-theme-name}) The graphical theme to use and its name. @item @code{auto-login-session} (default: @code{#f}) If true, this must be the name of the executable to start as the default session---e.g., @code{(file-append windowmaker "/bin/windowmaker")}. If false, a session described by one of the available @file{.desktop} files in @code{/run/current-system/profile} and @code{~/.guix-profile} will be used. @quotation Note You must install at least one window manager in the system profile or in your user profile. Failing to do that, if @code{auto-login-session} is false, you will be unable to log in. @end quotation @item @code{xorg-configuration} (default @code{(xorg-configuration)}) Configuration of the Xorg graphical server. @item @code{display} (default @code{":0"}) The display on which to start the Xorg graphical server. @item @code{vt} (default @code{"vt7"}) The VT on which to start the Xorg graphical server. @item @code{xauth} (default: @code{xauth}) The XAuth package to use. @item @code{shepherd} (default: @code{shepherd}) The Shepherd package used when invoking @command{halt} and @command{reboot}. @item @code{sessreg} (default: @code{sessreg}) The sessreg package used in order to register the session. @item @code{slim} (default: @code{slim}) The SLiM package to use. @end table @end deftp @defvr {Scheme Variable} %default-theme @defvrx {Scheme Variable} %default-theme-name The default SLiM theme and its name. @end defvr @deftp {Data Type} sddm-configuration This is the data type representing the SDDM service configuration. @table @asis @item @code{display-server} (default: "x11") Select display server to use for the greeter. Valid values are @samp{"x11"} or @samp{"wayland"}. @item @code{numlock} (default: "on") Valid values are @samp{"on"}, @samp{"off"} or @samp{"none"}. @item @code{halt-command} (default @code{#~(string-apppend #$shepherd "/sbin/halt")}) Command to run when halting. @item @code{reboot-command} (default @code{#~(string-append #$shepherd "/sbin/reboot")}) Command to run when rebooting. @item @code{theme} (default "maldives") Theme to use. Default themes provided by SDDM are @samp{"elarun"}, @samp{"maldives"} or @samp{"maya"}. @item @code{themes-directory} (default "/run/current-system/profile/share/sddm/themes") Directory to look for themes. @item @code{faces-directory} (default "/run/current-system/profile/share/sddm/faces") Directory to look for faces. @item @code{default-path} (default "/run/current-system/profile/bin") Default PATH to use. @item @code{minimum-uid} (default: 1000) Minimum UID displayed in SDDM and allowed for log-in. @item @code{maximum-uid} (default: 2000) Maximum UID to display in SDDM. @item @code{remember-last-user?} (default #t) Remember last user. @item @code{remember-last-session?} (default #t) Remember last session. @item @code{hide-users} (default "") Usernames to hide from SDDM greeter. @item @code{hide-shells} (default @code{#~(string-append #$shadow "/sbin/nologin")}) Users with shells listed will be hidden from the SDDM greeter. @item @code{session-command} (default @code{#~(string-append #$sddm "/share/sddm/scripts/wayland-session")}) Script to run before starting a wayland session. @item @code{sessions-directory} (default "/run/current-system/profile/share/wayland-sessions") Directory to look for desktop files starting wayland sessions. @item @code{xorg-configuration} (default @code{(xorg-configuration)}) Configuration of the Xorg graphical server. @item @code{xauth-path} (default @code{#~(string-append #$xauth "/bin/xauth")}) Path to xauth. @item @code{xephyr-path} (default @code{#~(string-append #$xorg-server "/bin/Xephyr")}) Path to Xephyr. @item @code{xdisplay-start} (default @code{#~(string-append #$sddm "/share/sddm/scripts/Xsetup")}) Script to run after starting xorg-server. @item @code{xdisplay-stop} (default @code{#~(string-append #$sddm "/share/sddm/scripts/Xstop")}) Script to run before stopping xorg-server. @item @code{xsession-command} (default: @code{xinitrc}) Script to run before starting a X session. @item @code{xsessions-directory} (default: "/run/current-system/profile/share/xsessions") Directory to look for desktop files starting X sessions. @item @code{minimum-vt} (default: 7) Minimum VT to use. @item @code{auto-login-user} (default "") User to use for auto-login. @item @code{auto-login-session} (default "") Desktop file to use for auto-login. @item @code{relogin?} (default #f) Relogin after logout. @end table @end deftp @cindex login manager @cindex X11 login @defvr {Scheme Variable} sddm-service-type This is the type of the service to run the @uref{https://github.com/sddm/sddm,SDDM display manager}. Its value must be a @code{sddm-configuration} record (see below). Here's an example use: @lisp (service sddm-service-type (sddm-configuration (auto-login-user "alice") (auto-login-session "xfce.desktop"))) @end lisp @end defvr @deftp {Data Type} sddm-configuration This data type represents the configuration of the SDDM login manager. The available fields are: @table @asis @item @code{sddm} (default: @code{sddm}) The SDDM package to use. @item @code{display-server} (default: @code{"x11"}) This must be either @code{"x11"} or @code{"wayland"}. @c FIXME: Add more fields. @item @code{auto-login-user} (default: @code{""}) If non-empty, this is the user account under which to log in automatically. @item @code{auto-login-session} (default: @code{""}) If non-empty, this is the @file{.desktop} file name to use as the auto-login session. @end table @end deftp @cindex Xorg, configuration @deftp {Data Type} xorg-configuration This data type represents the configuration of the Xorg graphical display server. Note that there is no Xorg service; instead, the X server is started by a ``display manager'' such as GDM, SDDM, and SLiM. Thus, the configuration of these display managers aggregates an @code{xorg-configuration} record. @table @asis @item @code{modules} (default: @code{%default-xorg-modules}) This is a list of @dfn{module packages} loaded by the Xorg server---e.g., @code{xf86-video-vesa}, @code{xf86-input-keyboard}, and so on. @item @code{fonts} (default: @code{%default-xorg-fonts}) This is a list of font directories to add to the server's @dfn{font path}. @item @code{drivers} (default: @code{'()}) This must be either the empty list, in which case Xorg chooses a graphics driver automatically, or a list of driver names that will be tried in this order---e.g., @code{("modesetting" "vesa")}. @item @code{resolutions} (default: @code{'()}) When @code{resolutions} is the empty list, Xorg chooses an appropriate screen resolution. Otherwise, it must be a list of resolutions---e.g., @code{((1024 768) (640 480))}. @cindex keyboard layout, for Xorg @cindex keymap, for Xorg @item @code{keyboard-layout} (default: @code{#f}) If this is @code{#f}, Xorg uses the default keyboard layout---usually US English (``qwerty'') for a 105-key PC keyboard. Otherwise this must be a @code{keyboard-layout} object specifying the keyboard layout in use when Xorg is running. @xref{Keyboard Layout}, for more information on how to specify the keyboard layout. @item @code{extra-config} (default: @code{'()}) This is a list of strings or objects appended to the configuration file. It is used to pass extra text to be added verbatim to the configuration file. @item @code{server} (default: @code{xorg-server}) This is the package providing the Xorg server. @item @code{server-arguments} (default: @code{%default-xorg-server-arguments}) This is the list of command-line arguments to pass to the X server. The default is @code{-nolisten tcp}. @end table @end deftp @deffn {Scheme Procedure} set-xorg-configuration @var{config} @ [@var{login-manager-service-type}] Tell the log-in manager (of type @var{login-manager-service-type}) to use @var{config}, an @code{} record. Since the Xorg configuration is embedded in the log-in manager's configuration---e.g., @code{gdm-configuration}---this procedure provides a shorthand to set the Xorg configuration. @end deffn @deffn {Scheme Procedure} xorg-start-command [@var{config}] Return a @code{startx} script in which the modules, fonts, etc. specified in @var{config}, are available. The result should be used in place of @code{startx}. Usually the X server is started by a login manager. @end deffn @deffn {Scheme Procedure} screen-locker-service @var{package} [@var{program}] Add @var{package}, a package for a screen locker or screen saver whose command is @var{program}, to the set of setuid programs and add a PAM entry for it. For example: @lisp (screen-locker-service xlockmore "xlock") @end lisp makes the good ol' XlockMore usable. @end deffn @node Printing Services @subsection Printing Services @cindex printer support with CUPS The @code{(gnu services cups)} module provides a Guix service definition for the CUPS printing service. To add printer support to a Guix system, add a @code{cups-service} to the operating system definition: @deffn {Scheme Variable} cups-service-type The service type for the CUPS print server. Its value should be a valid CUPS configuration (see below). To use the default settings, simply write: @lisp (service cups-service-type) @end lisp @end deffn The CUPS configuration controls the basic things about your CUPS installation: what interfaces it listens on, what to do if a print job fails, how much logging to do, and so on. To actually add a printer, you have to visit the @url{http://localhost:631} URL, or use a tool such as GNOME's printer configuration services. By default, configuring a CUPS service will generate a self-signed certificate if needed, for secure connections to the print server. Suppose you want to enable the Web interface of CUPS and also add support for Epson printers @i{via} the @code{epson-inkjet-printer-escpr} package and for HP printers @i{via} the @code{hplip-minimal} package. You can do that directly, like this (you need to use the @code{(gnu packages cups)} module): @lisp (service cups-service-type (cups-configuration (web-interface? #t) (extensions (list cups-filters epson-inkjet-printer-escpr hplip-minimal)))) @end lisp Note: If you wish to use the Qt5 based GUI which comes with the hplip package then it is suggested that you install the @code{hplip} package, either in your OS configuration file or as your user. The available configuration parameters follow. Each parameter definition is preceded by its type; for example, @samp{string-list foo} indicates that the @code{foo} parameter should be specified as a list of strings. There is also a way to specify the configuration as a string, if you have an old @code{cupsd.conf} file that you want to port over from some other system; see the end for more details. @c The following documentation was initially generated by @c (generate-documentation) in (gnu services cups). Manually maintained @c documentation is better, so we shouldn't hesitate to edit below as @c needed. However if the change you want to make to this documentation @c can be done in an automated way, it's probably easier to change @c (generate-documentation) than to make it below and have to deal with @c the churn as CUPS updates. Available @code{cups-configuration} fields are: @deftypevr {@code{cups-configuration} parameter} package cups The CUPS package. @end deftypevr @deftypevr {@code{cups-configuration} parameter} package-list extensions (default: @code{(list brlaser cups-filters epson-inkjet-printer-escpr foomatic-filters hplip-minimal splix)}) Drivers and other extensions to the CUPS package. @end deftypevr @deftypevr {@code{cups-configuration} parameter} files-configuration files-configuration Configuration of where to write logs, what directories to use for print spools, and related privileged configuration parameters. Available @code{files-configuration} fields are: @deftypevr {@code{files-configuration} parameter} log-location access-log Defines the access log filename. Specifying a blank filename disables access log generation. The value @code{stderr} causes log entries to be sent to the standard error file when the scheduler is running in the foreground, or to the system log daemon when run in the background. The value @code{syslog} causes log entries to be sent to the system log daemon. The server name may be included in filenames using the string @code{%s}, as in @code{/var/log/cups/%s-access_log}. Defaults to @samp{"/var/log/cups/access_log"}. @end deftypevr @deftypevr {@code{files-configuration} parameter} file-name cache-dir Where CUPS should cache data. Defaults to @samp{"/var/cache/cups"}. @end deftypevr @deftypevr {@code{files-configuration} parameter} string config-file-perm Specifies the permissions for all configuration files that the scheduler writes. Note that the permissions for the printers.conf file are currently masked to only allow access from the scheduler user (typically root). This is done because printer device URIs sometimes contain sensitive authentication information that should not be generally known on the system. There is no way to disable this security feature. Defaults to @samp{"0640"}. @end deftypevr @deftypevr {@code{files-configuration} parameter} log-location error-log Defines the error log filename. Specifying a blank filename disables error log generation. The value @code{stderr} causes log entries to be sent to the standard error file when the scheduler is running in the foreground, or to the system log daemon when run in the background. The value @code{syslog} causes log entries to be sent to the system log daemon. The server name may be included in filenames using the string @code{%s}, as in @code{/var/log/cups/%s-error_log}. Defaults to @samp{"/var/log/cups/error_log"}. @end deftypevr @deftypevr {@code{files-configuration} parameter} string fatal-errors Specifies which errors are fatal, causing the scheduler to exit. The kind strings are: @table @code @item none No errors are fatal. @item all All of the errors below are fatal. @item browse Browsing initialization errors are fatal, for example failed connections to the DNS-SD daemon. @item config Configuration file syntax errors are fatal. @item listen Listen or Port errors are fatal, except for IPv6 failures on the loopback or @code{any} addresses. @item log Log file creation or write errors are fatal. @item permissions Bad startup file permissions are fatal, for example shared TLS certificate and key files with world-read permissions. @end table Defaults to @samp{"all -browse"}. @end deftypevr @deftypevr {@code{files-configuration} parameter} boolean file-device? Specifies whether the file pseudo-device can be used for new printer queues. The URI @uref{file:///dev/null} is always allowed. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{files-configuration} parameter} string group Specifies the group name or ID that will be used when executing external programs. Defaults to @samp{"lp"}. @end deftypevr @deftypevr {@code{files-configuration} parameter} string log-file-perm Specifies the permissions for all log files that the scheduler writes. Defaults to @samp{"0644"}. @end deftypevr @deftypevr {@code{files-configuration} parameter} log-location page-log Defines the page log filename. Specifying a blank filename disables page log generation. The value @code{stderr} causes log entries to be sent to the standard error file when the scheduler is running in the foreground, or to the system log daemon when run in the background. The value @code{syslog} causes log entries to be sent to the system log daemon. The server name may be included in filenames using the string @code{%s}, as in @code{/var/log/cups/%s-page_log}. Defaults to @samp{"/var/log/cups/page_log"}. @end deftypevr @deftypevr {@code{files-configuration} parameter} string remote-root Specifies the username that is associated with unauthenticated accesses by clients claiming to be the root user. The default is @code{remroot}. Defaults to @samp{"remroot"}. @end deftypevr @deftypevr {@code{files-configuration} parameter} file-name request-root Specifies the directory that contains print jobs and other HTTP request data. Defaults to @samp{"/var/spool/cups"}. @end deftypevr @deftypevr {@code{files-configuration} parameter} sandboxing sandboxing Specifies the level of security sandboxing that is applied to print filters, backends, and other child processes of the scheduler; either @code{relaxed} or @code{strict}. This directive is currently only used/supported on macOS. Defaults to @samp{strict}. @end deftypevr @deftypevr {@code{files-configuration} parameter} file-name server-keychain Specifies the location of TLS certificates and private keys. CUPS will look for public and private keys in this directory: @file{.crt} files for PEM-encoded certificates and corresponding @file{.key} files for PEM-encoded private keys. Defaults to @samp{"/etc/cups/ssl"}. @end deftypevr @deftypevr {@code{files-configuration} parameter} file-name server-root Specifies the directory containing the server configuration files. Defaults to @samp{"/etc/cups"}. @end deftypevr @deftypevr {@code{files-configuration} parameter} boolean sync-on-close? Specifies whether the scheduler calls fsync(2) after writing configuration or state files. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{files-configuration} parameter} space-separated-string-list system-group Specifies the group(s) to use for @code{@@SYSTEM} group authentication. @end deftypevr @deftypevr {@code{files-configuration} parameter} file-name temp-dir Specifies the directory where temporary files are stored. Defaults to @samp{"/var/spool/cups/tmp"}. @end deftypevr @deftypevr {@code{files-configuration} parameter} string user Specifies the user name or ID that is used when running external programs. Defaults to @samp{"lp"}. @end deftypevr @deftypevr {@code{files-configuration} parameter} string set-env Set the specified environment variable to be passed to child processes. Defaults to @samp{"variable value"}. @end deftypevr @end deftypevr @deftypevr {@code{cups-configuration} parameter} access-log-level access-log-level Specifies the logging level for the AccessLog file. The @code{config} level logs when printers and classes are added, deleted, or modified and when configuration files are accessed or updated. The @code{actions} level logs when print jobs are submitted, held, released, modified, or canceled, and any of the conditions for @code{config}. The @code{all} level logs all requests. Defaults to @samp{actions}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} boolean auto-purge-jobs? Specifies whether to purge job history data automatically when it is no longer required for quotas. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} comma-separated-string-list browse-dns-sd-sub-types Specifies a list of DNS-SD sub-types to advertise for each shared printer. For example, @samp{"_cups" "_print"} will tell network clients that both CUPS sharing and IPP Everywhere are supported. Defaults to @samp{"_cups"}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} browse-local-protocols browse-local-protocols Specifies which protocols to use for local printer sharing. Defaults to @samp{dnssd}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} boolean browse-web-if? Specifies whether the CUPS web interface is advertised. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} boolean browsing? Specifies whether shared printers are advertised. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} string classification Specifies the security classification of the server. Any valid banner name can be used, including @samp{"classified"}, @samp{"confidential"}, @samp{"secret"}, @samp{"topsecret"}, and @samp{"unclassified"}, or the banner can be omitted to disable secure printing functions. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} boolean classify-override? Specifies whether users may override the classification (cover page) of individual print jobs using the @code{job-sheets} option. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} default-auth-type default-auth-type Specifies the default type of authentication to use. Defaults to @samp{Basic}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} default-encryption default-encryption Specifies whether encryption will be used for authenticated requests. Defaults to @samp{Required}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} string default-language Specifies the default language to use for text and web content. Defaults to @samp{"en"}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} string default-paper-size Specifies the default paper size for new print queues. @samp{"Auto"} uses a locale-specific default, while @samp{"None"} specifies there is no default paper size. Specific size names are typically @samp{"Letter"} or @samp{"A4"}. Defaults to @samp{"Auto"}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} string default-policy Specifies the default access policy to use. Defaults to @samp{"default"}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} boolean default-shared? Specifies whether local printers are shared by default. Defaults to @samp{#t}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} non-negative-integer dirty-clean-interval Specifies the delay for updating of configuration and state files, in seconds. A value of 0 causes the update to happen as soon as possible, typically within a few milliseconds. Defaults to @samp{30}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} error-policy error-policy Specifies what to do when an error occurs. Possible values are @code{abort-job}, which will discard the failed print job; @code{retry-job}, which will retry the job at a later time; @code{retry-current-job}, which retries the failed job immediately; and @code{stop-printer}, which stops the printer. Defaults to @samp{stop-printer}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} non-negative-integer filter-limit Specifies the maximum cost of filters that are run concurrently, which can be used to minimize disk, memory, and CPU resource problems. A limit of 0 disables filter limiting. An average print to a non-PostScript printer needs a filter limit of about 200. A PostScript printer needs about half that (100). Setting the limit below these thresholds will effectively limit the scheduler to printing a single job at any time. Defaults to @samp{0}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} non-negative-integer filter-nice Specifies the scheduling priority of filters that are run to print a job. The nice value ranges from 0, the highest priority, to 19, the lowest priority. Defaults to @samp{0}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} host-name-lookups host-name-lookups Specifies whether to do reverse lookups on connecting clients. The @code{double} setting causes @code{cupsd} to verify that the hostname resolved from the address matches one of the addresses returned for that hostname. Double lookups also prevent clients with unregistered addresses from connecting to your server. Only set this option to @code{#t} or @code{double} if absolutely required. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} non-negative-integer job-kill-delay Specifies the number of seconds to wait before killing the filters and backend associated with a canceled or held job. Defaults to @samp{30}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} non-negative-integer job-retry-interval Specifies the interval between retries of jobs in seconds. This is typically used for fax queues but can also be used with normal print queues whose error policy is @code{retry-job} or @code{retry-current-job}. Defaults to @samp{30}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} non-negative-integer job-retry-limit Specifies the number of retries that are done for jobs. This is typically used for fax queues but can also be used with normal print queues whose error policy is @code{retry-job} or @code{retry-current-job}. Defaults to @samp{5}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} boolean keep-alive? Specifies whether to support HTTP keep-alive connections. Defaults to @samp{#t}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} non-negative-integer keep-alive-timeout Specifies how long an idle client connection remains open, in seconds. Defaults to @samp{30}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} non-negative-integer limit-request-body Specifies the maximum size of print files, IPP requests, and HTML form data. A limit of 0 disables the limit check. Defaults to @samp{0}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} multiline-string-list listen Listens on the specified interfaces for connections. Valid values are of the form @var{address}:@var{port}, where @var{address} is either an IPv6 address enclosed in brackets, an IPv4 address, or @code{*} to indicate all addresses. Values can also be file names of local UNIX domain sockets. The Listen directive is similar to the Port directive but allows you to restrict access to specific interfaces or networks. @end deftypevr @deftypevr {@code{cups-configuration} parameter} non-negative-integer listen-back-log Specifies the number of pending connections that will be allowed. This normally only affects very busy servers that have reached the MaxClients limit, but can also be triggered by large numbers of simultaneous connections. When the limit is reached, the operating system will refuse additional connections until the scheduler can accept the pending ones. Defaults to @samp{128}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} location-access-control-list location-access-controls Specifies a set of additional access controls. Available @code{location-access-controls} fields are: @deftypevr {@code{location-access-controls} parameter} file-name path Specifies the URI path to which the access control applies. @end deftypevr @deftypevr {@code{location-access-controls} parameter} access-control-list access-controls Access controls for all access to this path, in the same format as the @code{access-controls} of @code{operation-access-control}. Defaults to @samp{()}. @end deftypevr @deftypevr {@code{location-access-controls} parameter} method-access-control-list method-access-controls Access controls for method-specific access to this path. Defaults to @samp{()}. Available @code{method-access-controls} fields are: @deftypevr {@code{method-access-controls} parameter} boolean reverse? If @code{#t}, apply access controls to all methods except the listed methods. Otherwise apply to only the listed methods. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{method-access-controls} parameter} method-list methods Methods to which this access control applies. Defaults to @samp{()}. @end deftypevr @deftypevr {@code{method-access-controls} parameter} access-control-list access-controls Access control directives, as a list of strings. Each string should be one directive, such as @samp{"Order allow,deny"}. Defaults to @samp{()}. @end deftypevr @end deftypevr @end deftypevr @deftypevr {@code{cups-configuration} parameter} non-negative-integer log-debug-history Specifies the number of debugging messages that are retained for logging if an error occurs in a print job. Debug messages are logged regardless of the LogLevel setting. Defaults to @samp{100}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} log-level log-level Specifies the level of logging for the ErrorLog file. The value @code{none} stops all logging while @code{debug2} logs everything. Defaults to @samp{info}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} log-time-format log-time-format Specifies the format of the date and time in the log files. The value @code{standard} logs whole seconds while @code{usecs} logs microseconds. Defaults to @samp{standard}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} non-negative-integer max-clients Specifies the maximum number of simultaneous clients that are allowed by the scheduler. Defaults to @samp{100}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} non-negative-integer max-clients-per-host Specifies the maximum number of simultaneous clients that are allowed from a single address. Defaults to @samp{100}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} non-negative-integer max-copies Specifies the maximum number of copies that a user can print of each job. Defaults to @samp{9999}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} non-negative-integer max-hold-time Specifies the maximum time a job may remain in the @code{indefinite} hold state before it is canceled. A value of 0 disables cancellation of held jobs. Defaults to @samp{0}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} non-negative-integer max-jobs Specifies the maximum number of simultaneous jobs that are allowed. Set to 0 to allow an unlimited number of jobs. Defaults to @samp{500}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} non-negative-integer max-jobs-per-printer Specifies the maximum number of simultaneous jobs that are allowed per printer. A value of 0 allows up to MaxJobs jobs per printer. Defaults to @samp{0}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} non-negative-integer max-jobs-per-user Specifies the maximum number of simultaneous jobs that are allowed per user. A value of 0 allows up to MaxJobs jobs per user. Defaults to @samp{0}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} non-negative-integer max-job-time Specifies the maximum time a job may take to print before it is canceled, in seconds. Set to 0 to disable cancellation of ``stuck'' jobs. Defaults to @samp{10800}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} non-negative-integer max-log-size Specifies the maximum size of the log files before they are rotated, in bytes. The value 0 disables log rotation. Defaults to @samp{1048576}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} non-negative-integer multiple-operation-timeout Specifies the maximum amount of time to allow between files in a multiple file print job, in seconds. Defaults to @samp{300}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} string page-log-format Specifies the format of PageLog lines. Sequences beginning with percent (@samp{%}) characters are replaced with the corresponding information, while all other characters are copied literally. The following percent sequences are recognized: @table @samp @item %% insert a single percent character @item %@{name@} insert the value of the specified IPP attribute @item %C insert the number of copies for the current page @item %P insert the current page number @item %T insert the current date and time in common log format @item %j insert the job ID @item %p insert the printer name @item %u insert the username @end table A value of the empty string disables page logging. The string @code{%p %u %j %T %P %C %@{job-billing@} %@{job-originating-host-name@} %@{job-name@} %@{media@} %@{sides@}} creates a page log with the standard items. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} environment-variables environment-variables Passes the specified environment variable(s) to child processes; a list of strings. Defaults to @samp{()}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} policy-configuration-list policies Specifies named access control policies. Available @code{policy-configuration} fields are: @deftypevr {@code{policy-configuration} parameter} string name Name of the policy. @end deftypevr @deftypevr {@code{policy-configuration} parameter} string job-private-access Specifies an access list for a job's private values. @code{@@ACL} maps to the printer's requesting-user-name-allowed or requesting-user-name-denied values. @code{@@OWNER} maps to the job's owner. @code{@@SYSTEM} maps to the groups listed for the @code{system-group} field of the @code{files-config} configuration, which is reified into the @code{cups-files.conf(5)} file. Other possible elements of the access list include specific user names, and @code{@@@var{group}} to indicate members of a specific group. The access list may also be simply @code{all} or @code{default}. Defaults to @samp{"@@OWNER @@SYSTEM"}. @end deftypevr @deftypevr {@code{policy-configuration} parameter} string job-private-values Specifies the list of job values to make private, or @code{all}, @code{default}, or @code{none}. Defaults to @samp{"job-name job-originating-host-name job-originating-user-name phone"}. @end deftypevr @deftypevr {@code{policy-configuration} parameter} string subscription-private-access Specifies an access list for a subscription's private values. @code{@@ACL} maps to the printer's requesting-user-name-allowed or requesting-user-name-denied values. @code{@@OWNER} maps to the job's owner. @code{@@SYSTEM} maps to the groups listed for the @code{system-group} field of the @code{files-config} configuration, which is reified into the @code{cups-files.conf(5)} file. Other possible elements of the access list include specific user names, and @code{@@@var{group}} to indicate members of a specific group. The access list may also be simply @code{all} or @code{default}. Defaults to @samp{"@@OWNER @@SYSTEM"}. @end deftypevr @deftypevr {@code{policy-configuration} parameter} string subscription-private-values Specifies the list of job values to make private, or @code{all}, @code{default}, or @code{none}. Defaults to @samp{"notify-events notify-pull-method notify-recipient-uri notify-subscriber-user-name notify-user-data"}. @end deftypevr @deftypevr {@code{policy-configuration} parameter} operation-access-control-list access-controls Access control by IPP operation. Defaults to @samp{()}. @end deftypevr @end deftypevr @deftypevr {@code{cups-configuration} parameter} boolean-or-non-negative-integer preserve-job-files Specifies whether job files (documents) are preserved after a job is printed. If a numeric value is specified, job files are preserved for the indicated number of seconds after printing. Otherwise a boolean value applies indefinitely. Defaults to @samp{86400}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} boolean-or-non-negative-integer preserve-job-history Specifies whether the job history is preserved after a job is printed. If a numeric value is specified, the job history is preserved for the indicated number of seconds after printing. If @code{#t}, the job history is preserved until the MaxJobs limit is reached. Defaults to @samp{#t}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} non-negative-integer reload-timeout Specifies the amount of time to wait for job completion before restarting the scheduler. Defaults to @samp{30}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} string rip-cache Specifies the maximum amount of memory to use when converting documents into bitmaps for a printer. Defaults to @samp{"128m"}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} string server-admin Specifies the email address of the server administrator. Defaults to @samp{"root@@localhost.localdomain"}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} host-name-list-or-* server-alias The ServerAlias directive is used for HTTP Host header validation when clients connect to the scheduler from external interfaces. Using the special name @code{*} can expose your system to known browser-based DNS rebinding attacks, even when accessing sites through a firewall. If the auto-discovery of alternate names does not work, we recommend listing each alternate name with a ServerAlias directive instead of using @code{*}. Defaults to @samp{*}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} string server-name Specifies the fully-qualified host name of the server. Defaults to @samp{"localhost"}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} server-tokens server-tokens Specifies what information is included in the Server header of HTTP responses. @code{None} disables the Server header. @code{ProductOnly} reports @code{CUPS}. @code{Major} reports @code{CUPS 2}. @code{Minor} reports @code{CUPS 2.0}. @code{Minimal} reports @code{CUPS 2.0.0}. @code{OS} reports @code{CUPS 2.0.0 (@var{uname})} where @var{uname} is the output of the @code{uname} command. @code{Full} reports @code{CUPS 2.0.0 (@var{uname}) IPP/2.0}. Defaults to @samp{Minimal}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} multiline-string-list ssl-listen Listens on the specified interfaces for encrypted connections. Valid values are of the form @var{address}:@var{port}, where @var{address} is either an IPv6 address enclosed in brackets, an IPv4 address, or @code{*} to indicate all addresses. Defaults to @samp{()}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} ssl-options ssl-options Sets encryption options. By default, CUPS only supports encryption using TLS v1.0 or higher using known secure cipher suites. Security is reduced when @code{Allow} options are used, and enhanced when @code{Deny} options are used. The @code{AllowRC4} option enables the 128-bit RC4 cipher suites, which are required for some older clients. The @code{AllowSSL3} option enables SSL v3.0, which is required for some older clients that do not support TLS v1.0. The @code{DenyCBC} option disables all CBC cipher suites. The @code{DenyTLS1.0} option disables TLS v1.0 support - this sets the minimum protocol version to TLS v1.1. Defaults to @samp{()}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} boolean strict-conformance? Specifies whether the scheduler requires clients to strictly adhere to the IPP specifications. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} non-negative-integer timeout Specifies the HTTP request timeout, in seconds. Defaults to @samp{300}. @end deftypevr @deftypevr {@code{cups-configuration} parameter} boolean web-interface? Specifies whether the web interface is enabled. Defaults to @samp{#f}. @end deftypevr At this point you're probably thinking ``oh dear, Guix manual, I like you but you can stop already with the configuration options''. Indeed. However, one more point: it could be that you have an existing @code{cupsd.conf} that you want to use. In that case, you can pass an @code{opaque-cups-configuration} as the configuration of a @code{cups-service-type}. Available @code{opaque-cups-configuration} fields are: @deftypevr {@code{opaque-cups-configuration} parameter} package cups The CUPS package. @end deftypevr @deftypevr {@code{opaque-cups-configuration} parameter} string cupsd.conf The contents of the @code{cupsd.conf}, as a string. @end deftypevr @deftypevr {@code{opaque-cups-configuration} parameter} string cups-files.conf The contents of the @code{cups-files.conf} file, as a string. @end deftypevr For example, if your @code{cupsd.conf} and @code{cups-files.conf} are in strings of the same name, you could instantiate a CUPS service like this: @lisp (service cups-service-type (opaque-cups-configuration (cupsd.conf cupsd.conf) (cups-files.conf cups-files.conf))) @end lisp @node Desktop Services @subsection Desktop Services The @code{(gnu services desktop)} module provides services that are usually useful in the context of a ``desktop'' setup---that is, on a machine running a graphical display server, possibly with graphical user interfaces, etc. It also defines services that provide specific desktop environments like GNOME, Xfce or MATE. To simplify things, the module defines a variable containing the set of services that users typically expect on a machine with a graphical environment and networking: @defvr {Scheme Variable} %desktop-services This is a list of services that builds upon @code{%base-services} and adds or adjusts services for a typical ``desktop'' setup. In particular, it adds a graphical login manager (@pxref{X Window, @code{gdm-service-type}}), screen lockers, a network management tool (@pxref{Networking Services, @code{network-manager-service-type}}) with modem support (@pxref{Networking Services, @code{modem-manager-service-type}}), energy and color management services, the @code{elogind} login and seat manager, the Polkit privilege service, the GeoClue location service, the AccountsService daemon that allows authorized users change system passwords, an NTP client (@pxref{Networking Services}), the Avahi daemon, and has the name service switch service configured to be able to use @code{nss-mdns} (@pxref{Name Service Switch, mDNS}). @end defvr The @code{%desktop-services} variable can be used as the @code{services} field of an @code{operating-system} declaration (@pxref{operating-system Reference, @code{services}}). Additionally, the @code{gnome-desktop-service-type}, @code{xfce-desktop-service}, @code{mate-desktop-service-type}, @code{lxqt-desktop-service-type} and @code{enlightenment-desktop-service-type} procedures can add GNOME, Xfce, MATE and/or Enlightenment to a system. To ``add GNOME'' means that system-level services like the backlight adjustment helpers and the power management utilities are added to the system, extending @code{polkit} and @code{dbus} appropriately, allowing GNOME to operate with elevated privileges on a limited number of special-purpose system interfaces. Additionally, adding a service made by @code{gnome-desktop-service-type} adds the GNOME metapackage to the system profile. Likewise, adding the Xfce service not only adds the @code{xfce} metapackage to the system profile, but it also gives the Thunar file manager the ability to open a ``root-mode'' file management window, if the user authenticates using the administrator's password via the standard polkit graphical interface. To ``add MATE'' means that @code{polkit} and @code{dbus} are extended appropriately, allowing MATE to operate with elevated privileges on a limited number of special-purpose system interfaces. Additionally, adding a service of type @code{mate-desktop-service-type} adds the MATE metapackage to the system profile. ``Adding Enlightenment'' means that @code{dbus} is extended appropriately, and several of Enlightenment's binaries are set as setuid, allowing Enlightenment's screen locker and other functionality to work as expected. The desktop environments in Guix use the Xorg display server by default. If you'd like to use the newer display server protocol called Wayland, you need to use the @code{sddm-service} instead of GDM as the graphical login manager. You should then select the ``GNOME (Wayland)'' session in SDDM. Alternatively you can also try starting GNOME on Wayland manually from a TTY with the command ``XDG_SESSION_TYPE=wayland exec dbus-run-session gnome-session``. Currently only GNOME has support for Wayland. @defvr {Scheme Variable} gnome-desktop-service-type This is the type of the service that adds the @uref{https://www.gnome.org, GNOME} desktop environment. Its value is a @code{gnome-desktop-configuration} object (see below). This service adds the @code{gnome} package to the system profile, and extends polkit with the actions from @code{gnome-settings-daemon}. @end defvr @deftp {Data Type} gnome-desktop-configuration Configuration record for the GNOME desktop environment. @table @asis @item @code{gnome} (default: @code{gnome}) The GNOME package to use. @end table @end deftp @defvr {Scheme Variable} xfce-desktop-service-type This is the type of a service to run the @uref{Xfce, https://xfce.org/} desktop environment. Its value is an @code{xfce-desktop-configuration} object (see below). This service adds the @code{xfce} package to the system profile, and extends polkit with the ability for @code{thunar} to manipulate the file system as root from within a user session, after the user has authenticated with the administrator's password. Note that @code{xfce4-panel} and its plugin packages should be installed in the same profile to ensure compatibility. When using this service, you should add extra plugins (@code{xfce4-whiskermenu-plugin}, @code{xfce4-weather-plugin}, etc.) to the @code{packages} field of your @code{operating-system}. @end defvr @deftp {Data Type} xfce-desktop-configuration Configuration record for the Xfce desktop environment. @table @asis @item @code{xfce} (default: @code{xfce}) The Xfce package to use. @end table @end deftp @deffn {Scheme Variable} mate-desktop-service-type This is the type of the service that runs the @uref{https://mate-desktop.org/, MATE desktop environment}. Its value is a @code{mate-desktop-configuration} object (see below). This service adds the @code{mate} package to the system profile, and extends polkit with the actions from @code{mate-settings-daemon}. @end deffn @deftp {Data Type} mate-desktop-configuration Configuration record for the MATE desktop environment. @table @asis @item @code{mate} (default: @code{mate}) The MATE package to use. @end table @end deftp @deffn {Scheme Variable} lxqt-desktop-service-type This is the type of the service that runs the @uref{https://lxqt.github.io, LXQt desktop environment}. Its value is a @code{lxqt-desktop-configuration} object (see below). This service adds the @code{lxqt} package to the system profile. @end deffn @deftp {Data Type} lxqt-desktop-configuration Configuration record for the LXQt desktop environment. @table @asis @item @code{lxqt} (default: @code{lxqt}) The LXQT package to use. @end table @end deftp @deffn {Scheme Variable} enlightenment-desktop-service-type Return a service that adds the @code{enlightenment} package to the system profile, and extends dbus with actions from @code{efl}. @end deffn @deftp {Data Type} enlightenment-desktop-service-configuration @table @asis @item @code{enlightenment} (default: @code{enlightenment}) The enlightenment package to use. @end table @end deftp Because the GNOME, Xfce and MATE desktop services pull in so many packages, the default @code{%desktop-services} variable doesn't include any of them by default. To add GNOME, Xfce or MATE, just @code{cons} them onto @code{%desktop-services} in the @code{services} field of your @code{operating-system}: @lisp (use-modules (gnu)) (use-service-modules desktop) (operating-system ... ;; cons* adds items to the list given as its last argument. (services (cons* (service gnome-desktop-service-type) (service xfce-desktop-service) %desktop-services)) ...) @end lisp These desktop environments will then be available as options in the graphical login window. The actual service definitions included in @code{%desktop-services} and provided by @code{(gnu services dbus)} and @code{(gnu services desktop)} are described below. @deffn {Scheme Procedure} dbus-service [#:dbus @var{dbus}] [#:services '()] Return a service that runs the ``system bus'', using @var{dbus}, with support for @var{services}. @uref{https://dbus.freedesktop.org/, D-Bus} is an inter-process communication facility. Its system bus is used to allow system services to communicate and to be notified of system-wide events. @var{services} must be a list of packages that provide an @file{etc/dbus-1/system.d} directory containing additional D-Bus configuration and policy files. For example, to allow avahi-daemon to use the system bus, @var{services} must be equal to @code{(list avahi)}. @end deffn @deffn {Scheme Procedure} elogind-service [#:config @var{config}] Return a service that runs the @code{elogind} login and seat management daemon. @uref{https://github.com/elogind/elogind, Elogind} exposes a D-Bus interface that can be used to know which users are logged in, know what kind of sessions they have open, suspend the system, inhibit system suspend, reboot the system, and other tasks. Elogind handles most system-level power events for a computer, for example suspending the system when a lid is closed, or shutting it down when the power button is pressed. The @var{config} keyword argument specifies the configuration for elogind, and should be the result of an @code{(elogind-configuration (@var{parameter} @var{value})...)} invocation. Available parameters and their default values are: @table @code @item kill-user-processes? @code{#f} @item kill-only-users @code{()} @item kill-exclude-users @code{("root")} @item inhibit-delay-max-seconds @code{5} @item handle-power-key @code{poweroff} @item handle-suspend-key @code{suspend} @item handle-hibernate-key @code{hibernate} @item handle-lid-switch @code{suspend} @item handle-lid-switch-docked @code{ignore} @item handle-lid-switch-external-power @code{ignore} @item power-key-ignore-inhibited? @code{#f} @item suspend-key-ignore-inhibited? @code{#f} @item hibernate-key-ignore-inhibited? @code{#f} @item lid-switch-ignore-inhibited? @code{#t} @item holdoff-timeout-seconds @code{30} @item idle-action @code{ignore} @item idle-action-seconds @code{(* 30 60)} @item runtime-directory-size-percent @code{10} @item runtime-directory-size @code{#f} @item remove-ipc? @code{#t} @item suspend-state @code{("mem" "standby" "freeze")} @item suspend-mode @code{()} @item hibernate-state @code{("disk")} @item hibernate-mode @code{("platform" "shutdown")} @item hybrid-sleep-state @code{("disk")} @item hybrid-sleep-mode @code{("suspend" "platform" "shutdown")} @end table @end deffn @deffn {Scheme Procedure} accountsservice-service @ [#:accountsservice @var{accountsservice}] Return a service that runs AccountsService, a system service that can list available accounts, change their passwords, and so on. AccountsService integrates with PolicyKit to enable unprivileged users to acquire the capability to modify their system configuration. @uref{https://www.freedesktop.org/wiki/Software/AccountsService/, the accountsservice web site} for more information. The @var{accountsservice} keyword argument is the @code{accountsservice} package to expose as a service. @end deffn @deffn {Scheme Procedure} polkit-service @ [#:polkit @var{polkit}] Return a service that runs the @uref{https://www.freedesktop.org/wiki/Software/polkit/, Polkit privilege management service}, which allows system administrators to grant access to privileged operations in a structured way. By querying the Polkit service, a privileged system component can know when it should grant additional capabilities to ordinary users. For example, an ordinary user can be granted the capability to suspend the system if the user is logged in locally. @end deffn @defvr {Scheme Variable} polkit-wheel-service Service that adds the @code{wheel} group as admins to the Polkit service. This makes it so that users in the @code{wheel} group are queried for their own passwords when performing administrative actions instead of @code{root}'s, similar to the behaviour used by @code{sudo}. @end defvr @defvr {Scheme Variable} upower-service-type Service that runs @uref{https://upower.freedesktop.org/, @command{upowerd}}, a system-wide monitor for power consumption and battery levels, with the given configuration settings. It implements the @code{org.freedesktop.UPower} D-Bus interface, and is notably used by GNOME. @end defvr @deftp {Data Type} upower-configuration Data type representation the configuration for UPower. @table @asis @item @code{upower} (default: @var{upower}) Package to use for @code{upower}. @item @code{watts-up-pro?} (default: @code{#f}) Enable the Watts Up Pro device. @item @code{poll-batteries?} (default: @code{#t}) Enable polling the kernel for battery level changes. @item @code{ignore-lid?} (default: @code{#f}) Ignore the lid state, this can be useful if it's incorrect on a device. @item @code{use-percentage-for-policy?} (default: @code{#f}) Whether battery percentage based policy should be used. The default is to use the time left, change to @code{#t} to use the percentage. @item @code{percentage-low} (default: @code{10}) When @code{use-percentage-for-policy?} is @code{#t}, this sets the percentage at which the battery is considered low. @item @code{percentage-critical} (default: @code{3}) When @code{use-percentage-for-policy?} is @code{#t}, this sets the percentage at which the battery is considered critical. @item @code{percentage-action} (default: @code{2}) When @code{use-percentage-for-policy?} is @code{#t}, this sets the percentage at which action will be taken. @item @code{time-low} (default: @code{1200}) When @code{use-time-for-policy?} is @code{#f}, this sets the time remaining in seconds at which the battery is considered low. @item @code{time-critical} (default: @code{300}) When @code{use-time-for-policy?} is @code{#f}, this sets the time remaining in seconds at which the battery is considered critical. @item @code{time-action} (default: @code{120}) When @code{use-time-for-policy?} is @code{#f}, this sets the time remaining in seconds at which action will be taken. @item @code{critical-power-action} (default: @code{'hybrid-sleep}) The action taken when @code{percentage-action} or @code{time-action} is reached (depending on the configuration of @code{use-percentage-for-policy?}). Possible values are: @itemize @bullet @item @code{'power-off} @item @code{'hibernate} @item @code{'hybrid-sleep}. @end itemize @end table @end deftp @deffn {Scheme Procedure} udisks-service [#:udisks @var{udisks}] Return a service for @uref{https://udisks.freedesktop.org/docs/latest/, UDisks}, a @dfn{disk management} daemon that provides user interfaces with notifications and ways to mount/unmount disks. Programs that talk to UDisks include the @command{udisksctl} command, part of UDisks, and GNOME Disks. Note that Udisks relies on the @command{mount} command, so it will only be able to use the file-system utilities installed in the system profile. For example if you want to be able to mount NTFS file-systems in read and write fashion, you'll need to have @code{ntfs-3g} installed system-wide. @end deffn @deffn {Scheme Variable} colord-service-type This is the type of the service that runs @command{colord}, a system service with a D-Bus interface to manage the color profiles of input and output devices such as screens and scanners. It is notably used by the GNOME Color Manager graphical tool. See @uref{https://www.freedesktop.org/software/colord/, the colord web site} for more information. @end deffn @deffn {Scheme Procedure} geoclue-application name [#:allowed? #t] [#:system? #f] [#:users '()] Return a configuration allowing an application to access GeoClue location data. @var{name} is the Desktop ID of the application, without the @code{.desktop} part. If @var{allowed?} is true, the application will have access to location information by default. The boolean @var{system?} value indicates whether an application is a system component or not. Finally @var{users} is a list of UIDs of all users for which this application is allowed location info access. An empty users list means that all users are allowed. @end deffn @cindex scanner access @deffn {Scheme Procedure} sane-service-type This service provides access to scanners @i{via} @uref{http://www.sane-project.org, SANE} by installing the necessary udev rules. @end deffn @defvr {Scheme Variable} %standard-geoclue-applications The standard list of well-known GeoClue application configurations, granting authority to the GNOME date-and-time utility to ask for the current location in order to set the time zone, and allowing the IceCat and Epiphany web browsers to request location information. IceCat and Epiphany both query the user before allowing a web page to know the user's location. @end defvr @deffn {Scheme Procedure} geoclue-service [#:colord @var{colord}] @ [#:whitelist '()] @ [#:wifi-geolocation-url "https://location.services.mozilla.com/v1/geolocate?key=geoclue"] @ [#:submit-data? #f] [#:wifi-submission-url "https://location.services.mozilla.com/v1/submit?key=geoclue"] @ [#:submission-nick "geoclue"] @ [#:applications %standard-geoclue-applications] Return a service that runs the GeoClue location service. This service provides a D-Bus interface to allow applications to request access to a user's physical location, and optionally to add information to online location databases. See @uref{https://wiki.freedesktop.org/www/Software/GeoClue/, the GeoClue web site} for more information. @end deffn @deffn {Scheme Procedure} bluetooth-service [#:bluez @var{bluez}] @ [@w{#:auto-enable? #f}] Return a service that runs the @command{bluetoothd} daemon, which manages all the Bluetooth devices and provides a number of D-Bus interfaces. When AUTO-ENABLE? is true, the bluetooth controller is powered automatically at boot, which can be useful when using a bluetooth keyboard or mouse. Users need to be in the @code{lp} group to access the D-Bus service. @end deffn @defvr {Scheme Variable} gnome-keyring-service-type This is the type of the service that adds the @uref{https://wiki.gnome.org/Projects/GnomeKeyring, GNOME Keyring}. Its value is a @code{gnome-keyring-configuration} object (see below). This service adds the @code{gnome-keyring} package to the system profile and extends PAM with entries using @code{pam_gnome_keyring.so}, unlocking a user's login keyring when they log in or setting its password with passwd. @end defvr @deftp {Data Type} gnome-keyring-configuration Configuration record for the GNOME Keyring service. @table @asis @item @code{keyring} (default: @code{gnome-keyring}) The GNOME keyring package to use. @item @code{pam-services} A list of @code{(@var{service} . @var{kind})} pairs denoting PAM services to extend, where @var{service} is the name of an existing service to extend and @var{kind} is one of @code{login} or @code{passwd}. If @code{login} is given, it adds an optional @code{pam_gnome_keyring.so} to the auth block without arguments and to the session block with @code{auto_start}. If @code{passwd} is given, it adds an optional @code{pam_gnome_keyring.so} to the password block without arguments. By default, this field contains ``gdm-password'' with the value @code{login} and ``passwd'' is with the value @code{passwd}. @end table @end deftp @node Sound Services @subsection Sound Services @cindex sound support @cindex ALSA @cindex PulseAudio, sound support The @code{(gnu services sound)} module provides a service to configure the Advanced Linux Sound Architecture (ALSA) system, which makes PulseAudio the preferred ALSA output driver. @deffn {Scheme Variable} alsa-service-type This is the type for the @uref{https://alsa-project.org/, Advanced Linux Sound Architecture} (ALSA) system, which generates the @file{/etc/asound.conf} configuration file. The value for this type is a @command{alsa-configuration} record as in this example: @lisp (service alsa-service-type) @end lisp See below for details about @code{alsa-configuration}. @end deffn @deftp {Data Type} alsa-configuration Data type representing the configuration for @code{alsa-service}. @table @asis @item @code{alsa-plugins} (default: @var{alsa-plugins}) @code{alsa-plugins} package to use. @item @code{pulseaudio?} (default: @var{#t}) Whether ALSA applications should transparently be made to use the @uref{https://www.pulseaudio.org/, PulseAudio} sound server. Using PulseAudio allows you to run several sound-producing applications at the same time and to individual control them @i{via} @command{pavucontrol}, among other things. @item @code{extra-options} (default: @var{""}) String to append to the @file{/etc/asound.conf} file. @end table @end deftp Individual users who want to override the system configuration of ALSA can do it with the @file{~/.asoundrc} file: @example # In guix, we have to specify the absolute path for plugins. pcm_type.jack @{ lib "/home/alice/.guix-profile/lib/alsa-lib/libasound_module_pcm_jack.so" @} # Routing ALSA to jack: # . pcm.rawjack @{ type jack playback_ports @{ 0 system:playback_1 1 system:playback_2 @} capture_ports @{ 0 system:capture_1 1 system:capture_2 @} @} pcm.!default @{ type plug slave @{ pcm "rawjack" @} @} @end example See @uref{https://www.alsa-project.org/main/index.php/Asoundrc} for the details. @deffn {Scheme Variable} pulseaudio-service-type This is the type for the @uref{https://www.pulseaudio.org/, PulseAudio} sound server. It exists to allow system overrides of the default settings via @code{pulseaudio-configuration}, see below. @quotation Warning This service overrides per-user configuration files. If you want PulseAudio to honor configuration files in @file{~/.config/pulse} you have to unset the environment variables @env{PULSE_CONFIG} and @env{PULSE_CLIENTCONFIG} in your @file{~/.bash_profile}. @end quotation @quotation Warning This service on its own does not ensure, that the @code{pulseaudio} package exists on your machine. It merely adds configuration files for it, as detailed below. In the (admittedly unlikely) case, that you find yourself without a @code{pulseaudio} package, consider enabling it through the @code{alsa-service-type} above. @end quotation @end deffn @deftp {Data Type} pulseaudio-configuration Data type representing the configuration for @code{pulseaudio-service}. @table @asis @item @code{client-conf} (default: @code{'()}) List of settings to set in @file{client.conf}. Accepts a list of strings or a symbol-value pairs. A string will be inserted as-is with a newline added. A pair will be formatted as ``key = value'', again with a newline added. @item @code{daemon-conf} (default: @code{'((flat-volumes . no))}) List of settings to set in @file{daemon.conf}, formatted just like @var{client-conf}. @item @code{script-file} (default: @code{(file-append pulseaudio "/etc/pulse/default.pa")}) Script file to use as @file{default.pa}. @item @code{system-script-file} (default: @code{(file-append pulseaudio "/etc/pulse/system.pa")}) Script file to use as @file{system.pa}. @end table @end deftp @deffn {Scheme Variable} ladspa-service-type This service sets the @var{LADSPA_PATH} variable, so that programs, which respect it, e.g. PulseAudio, can load LADSPA plugins. The following example will setup the service to enable modules from the @code{swh-plugins} package: @lisp (service ladspa-service-type (ladspa-configuration (plugins (list swh-plugins)))) @end lisp See @uref{http://plugin.org.uk/ladspa-swh/docs/ladspa-swh.html} for the details. @end deffn @node Database Services @subsection Database Services @cindex database @cindex SQL The @code{(gnu services databases)} module provides the following services. @subsubheading PostgreSQL The following example describes a PostgreSQL service with the default configuration. @lisp (service postgresql-service-type (postgresql-configuration (postgresql postgresql-10))) @end lisp If the services fails to start, it may be due to an incompatible cluster already present in @var{data-directory}. Adjust it (or, if you don't need the cluster anymore, delete @var{data-directory}), then restart the service. Peer authentication is used by default and the @code{postgres} user account has no shell, which prevents the direct execution of @code{psql} commands as this user. To use @code{psql}, you can temporarily log in as @code{postgres} using a shell, create a PostgreSQL superuser with the same name as one of the system users and then create the associated database. @example sudo -u postgres -s /bin/sh createuser --interactive createdb $MY_USER_LOGIN # Replace appropriately. @end example @deftp {Data Type} postgresql-configuration Data type representing the configuration for the @code{postgresql-service-type}. @table @asis @item @code{postgresql} PostgreSQL package to use for the service. @item @code{port} (default: @code{5432}) Port on which PostgreSQL should listen. @item @code{locale} (default: @code{"en_US.utf8"}) Locale to use as the default when creating the database cluster. @item @code{config-file} (default: @code{(postgresql-config-file)}) The configuration file to use when running PostgreSQL. The default behaviour uses the postgresql-config-file record with the default values for the fields. @item @code{data-directory} (default: @code{"/var/lib/postgresql/data"}) Directory in which to store the data. @item @code{extension-packages} (default: @code{'()}) @cindex postgresql extension-packages Additional extensions are loaded from packages listed in @var{extension-packages}. Extensions are available at runtime. For instance, to create a geographic database using the @code{postgis} extension, a user can configure the postgresql-service as in this example: @cindex postgis @lisp (use-package-modules databases geo) (operating-system ... ;; postgresql is required to run `psql' but postgis is not required for ;; proper operation. (packages (cons* postgresql %base-packages)) (services (cons* (service postgresql-service-type (postgresql-configuration (postgresql postgresql-10) (extension-packages (list postgis)))) %base-services))) @end lisp Then the extension becomes visible and you can initialise an empty geographic database in this way: @example psql -U postgres > create database postgistest; > \connect postgistest; > create extension postgis; > create extension postgis_topology; @end example There is no need to add this field for contrib extensions such as hstore or dblink as they are already loadable by postgresql. This field is only required to add extensions provided by other packages. @end table @end deftp @deftp {Data Type} postgresql-config-file Data type representing the PostgreSQL configuration file. As shown in the following example, this can be used to customize the configuration of PostgreSQL. Note that you can use any G-expression or filename in place of this record, if you already have a configuration file you'd like to use for example. @lisp (service postgresql-service-type (postgresql-configuration (config-file (postgresql-config-file (log-destination "stderr") (hba-file (plain-file "pg_hba.conf" " local all all trust host all all 127.0.0.1/32 md5 host all all ::1/128 md5")) (extra-config '(("session_preload_libraries" "'auto_explain'") ("random_page_cost" "2") ("auto_explain.log_min_duration" "'100ms'") ("work_mem" "'500MB'") ("logging_collector" "on") ("log_directory" "'/var/log/postgresql'"))))))) @end lisp @table @asis @item @code{log-destination} (default: @code{"syslog"}) The logging method to use for PostgreSQL. Multiple values are accepted, separated by commas. @item @code{hba-file} (default: @code{%default-postgres-hba}) Filename or G-expression for the host-based authentication configuration. @item @code{ident-file} (default: @code{%default-postgres-ident}) Filename or G-expression for the user name mapping configuration. @item @code{extra-config} (default: @code{'()}) List of additional keys and values to include in the PostgreSQL config file. Each entry in the list should be a list where the first element is the key, and the remaining elements are the values. @end table @end deftp @subsubheading MariaDB/MySQL @defvr {Scheme Variable} mysql-service-type This is the service type for a MySQL or MariaDB database server. Its value is a @code{mysql-configuration} object that specifies which package to use, as well as various settings for the @command{mysqld} daemon. @end defvr @deftp {Data Type} mysql-configuration Data type representing the configuration of @var{mysql-service-type}. @table @asis @item @code{mysql} (default: @var{mariadb}) Package object of the MySQL database server, can be either @var{mariadb} or @var{mysql}. For MySQL, a temporary root password will be displayed at activation time. For MariaDB, the root password is empty. @item @code{bind-address} (default: @code{"127.0.0.1"}) The IP on which to listen for network connections. Use @code{"0.0.0.0"} to bind to all available network interfaces. @item @code{port} (default: @code{3306}) TCP port on which the database server listens for incoming connections. @item @code{socket} (default: @code{"/run/mysqld/mysqld.sock"}) Socket file to use for local (non-network) connections. @item @code{extra-content} (default: @code{""}) Additional settings for the @file{my.cnf} configuration file. @item @code{auto-upgrade?} (default: @code{#t}) Whether to automatically run @command{mysql_upgrade} after starting the service. This is necessary to upgrade the @dfn{system schema} after ``major'' updates (such as switching from MariaDB 10.4 to 10.5), but can be disabled if you would rather do that manually. @end table @end deftp @subsubheading Memcached @defvr {Scheme Variable} memcached-service-type This is the service type for the @uref{https://memcached.org/, Memcached} service, which provides a distributed in memory cache. The value for the service type is a @code{memcached-configuration} object. @end defvr @lisp (service memcached-service-type) @end lisp @deftp {Data Type} memcached-configuration Data type representing the configuration of memcached. @table @asis @item @code{memcached} (default: @code{memcached}) The Memcached package to use. @item @code{interfaces} (default: @code{'("0.0.0.0")}) Network interfaces on which to listen. @item @code{tcp-port} (default: @code{11211}) Port on which to accept connections. @item @code{udp-port} (default: @code{11211}) Port on which to accept UDP connections on, a value of 0 will disable listening on a UDP socket. @item @code{additional-options} (default: @code{'()}) Additional command line options to pass to @code{memcached}. @end table @end deftp @subsubheading MongoDB @defvr {Scheme Variable} mongodb-service-type This is the service type for @uref{https://www.mongodb.com/, MongoDB}. The value for the service type is a @code{mongodb-configuration} object. @end defvr @lisp (service mongodb-service-type) @end lisp @deftp {Data Type} mongodb-configuration Data type representing the configuration of mongodb. @table @asis @item @code{mongodb} (default: @code{mongodb}) The MongoDB package to use. @item @code{config-file} (default: @code{%default-mongodb-configuration-file}) The configuration file for MongoDB. @item @code{data-directory} (default: @code{"/var/lib/mongodb"}) This value is used to create the directory, so that it exists and is owned by the mongodb user. It should match the data-directory which MongoDB is configured to use through the configuration file. @end table @end deftp @subsubheading Redis @defvr {Scheme Variable} redis-service-type This is the service type for the @uref{https://redis.io/, Redis} key/value store, whose value is a @code{redis-configuration} object. @end defvr @deftp {Data Type} redis-configuration Data type representing the configuration of redis. @table @asis @item @code{redis} (default: @code{redis}) The Redis package to use. @item @code{bind} (default: @code{"127.0.0.1"}) Network interface on which to listen. @item @code{port} (default: @code{6379}) Port on which to accept connections on, a value of 0 will disable listening on a TCP socket. @item @code{working-directory} (default: @code{"/var/lib/redis"}) Directory in which to store the database and related files. @end table @end deftp @node Mail Services @subsection Mail Services @cindex mail @cindex email The @code{(gnu services mail)} module provides Guix service definitions for email services: IMAP, POP3, and LMTP servers, as well as mail transport agents (MTAs). Lots of acronyms! These services are detailed in the subsections below. @subsubheading Dovecot Service @deffn {Scheme Procedure} dovecot-service [#:config (dovecot-configuration)] Return a service that runs the Dovecot IMAP/POP3/LMTP mail server. @end deffn By default, Dovecot does not need much configuration; the default configuration object created by @code{(dovecot-configuration)} will suffice if your mail is delivered to @code{~/Maildir}. A self-signed certificate will be generated for TLS-protected connections, though Dovecot will also listen on cleartext ports by default. There are a number of options, though, which mail administrators might need to change, and as is the case with other services, Guix allows the system administrator to specify these parameters via a uniform Scheme interface. For example, to specify that mail is located at @code{maildir~/.mail}, one would instantiate the Dovecot service like this: @lisp (dovecot-service #:config (dovecot-configuration (mail-location "maildir:~/.mail"))) @end lisp The available configuration parameters follow. Each parameter definition is preceded by its type; for example, @samp{string-list foo} indicates that the @code{foo} parameter should be specified as a list of strings. There is also a way to specify the configuration as a string, if you have an old @code{dovecot.conf} file that you want to port over from some other system; see the end for more details. @c The following documentation was initially generated by @c (generate-documentation) in (gnu services mail). Manually maintained @c documentation is better, so we shouldn't hesitate to edit below as @c needed. However if the change you want to make to this documentation @c can be done in an automated way, it's probably easier to change @c (generate-documentation) than to make it below and have to deal with @c the churn as dovecot updates. Available @code{dovecot-configuration} fields are: @deftypevr {@code{dovecot-configuration} parameter} package dovecot The dovecot package. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} comma-separated-string-list listen A list of IPs or hosts where to listen for connections. @samp{*} listens on all IPv4 interfaces, @samp{::} listens on all IPv6 interfaces. If you want to specify non-default ports or anything more complex, customize the address and port fields of the @samp{inet-listener} of the specific services you are interested in. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} protocol-configuration-list protocols List of protocols we want to serve. Available protocols include @samp{imap}, @samp{pop3}, and @samp{lmtp}. Available @code{protocol-configuration} fields are: @deftypevr {@code{protocol-configuration} parameter} string name The name of the protocol. @end deftypevr @deftypevr {@code{protocol-configuration} parameter} string auth-socket-path UNIX socket path to the master authentication server to find users. This is used by imap (for shared users) and lda. It defaults to @samp{"/var/run/dovecot/auth-userdb"}. @end deftypevr @deftypevr {@code{protocol-configuration} parameter} space-separated-string-list mail-plugins Space separated list of plugins to load. @end deftypevr @deftypevr {@code{protocol-configuration} parameter} non-negative-integer mail-max-userip-connections Maximum number of IMAP connections allowed for a user from each IP address. NOTE: The username is compared case-sensitively. Defaults to @samp{10}. @end deftypevr @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} service-configuration-list services List of services to enable. Available services include @samp{imap}, @samp{imap-login}, @samp{pop3}, @samp{pop3-login}, @samp{auth}, and @samp{lmtp}. Available @code{service-configuration} fields are: @deftypevr {@code{service-configuration} parameter} string kind The service kind. Valid values include @code{director}, @code{imap-login}, @code{pop3-login}, @code{lmtp}, @code{imap}, @code{pop3}, @code{auth}, @code{auth-worker}, @code{dict}, @code{tcpwrap}, @code{quota-warning}, or anything else. @end deftypevr @deftypevr {@code{service-configuration} parameter} listener-configuration-list listeners Listeners for the service. A listener is either a @code{unix-listener-configuration}, a @code{fifo-listener-configuration}, or an @code{inet-listener-configuration}. Defaults to @samp{()}. Available @code{unix-listener-configuration} fields are: @deftypevr {@code{unix-listener-configuration} parameter} string path Path to the file, relative to @code{base-dir} field. This is also used as the section name. @end deftypevr @deftypevr {@code{unix-listener-configuration} parameter} string mode The access mode for the socket. Defaults to @samp{"0600"}. @end deftypevr @deftypevr {@code{unix-listener-configuration} parameter} string user The user to own the socket. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{unix-listener-configuration} parameter} string group The group to own the socket. Defaults to @samp{""}. @end deftypevr Available @code{fifo-listener-configuration} fields are: @deftypevr {@code{fifo-listener-configuration} parameter} string path Path to the file, relative to @code{base-dir} field. This is also used as the section name. @end deftypevr @deftypevr {@code{fifo-listener-configuration} parameter} string mode The access mode for the socket. Defaults to @samp{"0600"}. @end deftypevr @deftypevr {@code{fifo-listener-configuration} parameter} string user The user to own the socket. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{fifo-listener-configuration} parameter} string group The group to own the socket. Defaults to @samp{""}. @end deftypevr Available @code{inet-listener-configuration} fields are: @deftypevr {@code{inet-listener-configuration} parameter} string protocol The protocol to listen for. @end deftypevr @deftypevr {@code{inet-listener-configuration} parameter} string address The address on which to listen, or empty for all addresses. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{inet-listener-configuration} parameter} non-negative-integer port The port on which to listen. @end deftypevr @deftypevr {@code{inet-listener-configuration} parameter} boolean ssl? Whether to use SSL for this service; @samp{yes}, @samp{no}, or @samp{required}. Defaults to @samp{#t}. @end deftypevr @end deftypevr @deftypevr {@code{service-configuration} parameter} non-negative-integer client-limit Maximum number of simultaneous client connections per process. Once this number of connections is received, the next incoming connection will prompt Dovecot to spawn another process. If set to 0, @code{default-client-limit} is used instead. Defaults to @samp{0}. @end deftypevr @deftypevr {@code{service-configuration} parameter} non-negative-integer service-count Number of connections to handle before starting a new process. Typically the only useful values are 0 (unlimited) or 1. 1 is more secure, but 0 is faster. . Defaults to @samp{1}. @end deftypevr @deftypevr {@code{service-configuration} parameter} non-negative-integer process-limit Maximum number of processes that can exist for this service. If set to 0, @code{default-process-limit} is used instead. Defaults to @samp{0}. @end deftypevr @deftypevr {@code{service-configuration} parameter} non-negative-integer process-min-avail Number of processes to always keep waiting for more connections. Defaults to @samp{0}. @end deftypevr @deftypevr {@code{service-configuration} parameter} non-negative-integer vsz-limit If you set @samp{service-count 0}, you probably need to grow this. Defaults to @samp{256000000}. @end deftypevr @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} dict-configuration dict Dict configuration, as created by the @code{dict-configuration} constructor. Available @code{dict-configuration} fields are: @deftypevr {@code{dict-configuration} parameter} free-form-fields entries A list of key-value pairs that this dict should hold. Defaults to @samp{()}. @end deftypevr @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} passdb-configuration-list passdbs A list of passdb configurations, each one created by the @code{passdb-configuration} constructor. Available @code{passdb-configuration} fields are: @deftypevr {@code{passdb-configuration} parameter} string driver The driver that the passdb should use. Valid values include @samp{pam}, @samp{passwd}, @samp{shadow}, @samp{bsdauth}, and @samp{static}. Defaults to @samp{"pam"}. @end deftypevr @deftypevr {@code{passdb-configuration} parameter} space-separated-string-list args Space separated list of arguments to the passdb driver. Defaults to @samp{""}. @end deftypevr @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} userdb-configuration-list userdbs List of userdb configurations, each one created by the @code{userdb-configuration} constructor. Available @code{userdb-configuration} fields are: @deftypevr {@code{userdb-configuration} parameter} string driver The driver that the userdb should use. Valid values include @samp{passwd} and @samp{static}. Defaults to @samp{"passwd"}. @end deftypevr @deftypevr {@code{userdb-configuration} parameter} space-separated-string-list args Space separated list of arguments to the userdb driver. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{userdb-configuration} parameter} free-form-args override-fields Override fields from passwd. Defaults to @samp{()}. @end deftypevr @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} plugin-configuration plugin-configuration Plug-in configuration, created by the @code{plugin-configuration} constructor. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} list-of-namespace-configuration namespaces List of namespaces. Each item in the list is created by the @code{namespace-configuration} constructor. Available @code{namespace-configuration} fields are: @deftypevr {@code{namespace-configuration} parameter} string name Name for this namespace. @end deftypevr @deftypevr {@code{namespace-configuration} parameter} string type Namespace type: @samp{private}, @samp{shared} or @samp{public}. Defaults to @samp{"private"}. @end deftypevr @deftypevr {@code{namespace-configuration} parameter} string separator Hierarchy separator to use. You should use the same separator for all namespaces or some clients get confused. @samp{/} is usually a good one. The default however depends on the underlying mail storage format. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{namespace-configuration} parameter} string prefix Prefix required to access this namespace. This needs to be different for all namespaces. For example @samp{Public/}. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{namespace-configuration} parameter} string location Physical location of the mailbox. This is in the same format as mail_location, which is also the default for it. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{namespace-configuration} parameter} boolean inbox? There can be only one INBOX, and this setting defines which namespace has it. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{namespace-configuration} parameter} boolean hidden? If namespace is hidden, it's not advertised to clients via NAMESPACE extension. You'll most likely also want to set @samp{list? #f}. This is mostly useful when converting from another server with different namespaces which you want to deprecate but still keep working. For example you can create hidden namespaces with prefixes @samp{~/mail/}, @samp{~%u/mail/} and @samp{mail/}. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{namespace-configuration} parameter} boolean list? Show the mailboxes under this namespace with the LIST command. This makes the namespace visible for clients that do not support the NAMESPACE extension. The special @code{children} value lists child mailboxes, but hides the namespace prefix. Defaults to @samp{#t}. @end deftypevr @deftypevr {@code{namespace-configuration} parameter} boolean subscriptions? Namespace handles its own subscriptions. If set to @code{#f}, the parent namespace handles them. The empty prefix should always have this as @code{#t}). Defaults to @samp{#t}. @end deftypevr @deftypevr {@code{namespace-configuration} parameter} mailbox-configuration-list mailboxes List of predefined mailboxes in this namespace. Defaults to @samp{()}. Available @code{mailbox-configuration} fields are: @deftypevr {@code{mailbox-configuration} parameter} string name Name for this mailbox. @end deftypevr @deftypevr {@code{mailbox-configuration} parameter} string auto @samp{create} will automatically create this mailbox. @samp{subscribe} will both create and subscribe to the mailbox. Defaults to @samp{"no"}. @end deftypevr @deftypevr {@code{mailbox-configuration} parameter} space-separated-string-list special-use List of IMAP @code{SPECIAL-USE} attributes as specified by RFC 6154. Valid values are @code{\All}, @code{\Archive}, @code{\Drafts}, @code{\Flagged}, @code{\Junk}, @code{\Sent}, and @code{\Trash}. Defaults to @samp{()}. @end deftypevr @end deftypevr @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} file-name base-dir Base directory where to store runtime data. Defaults to @samp{"/var/run/dovecot/"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string login-greeting Greeting message for clients. Defaults to @samp{"Dovecot ready."}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list login-trusted-networks List of trusted network ranges. Connections from these IPs are allowed to override their IP addresses and ports (for logging and for authentication checks). @samp{disable-plaintext-auth} is also ignored for these networks. Typically you would specify your IMAP proxy servers here. Defaults to @samp{()}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list login-access-sockets List of login access check sockets (e.g.@: tcpwrap). Defaults to @samp{()}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} boolean verbose-proctitle? Show more verbose process titles (in ps). Currently shows user name and IP address. Useful for seeing who is actually using the IMAP processes (e.g.@: shared mailboxes or if the same uid is used for multiple accounts). Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} boolean shutdown-clients? Should all processes be killed when Dovecot master process shuts down. Setting this to @code{#f} means that Dovecot can be upgraded without forcing existing client connections to close (although that could also be a problem if the upgrade is e.g.@: due to a security fix). Defaults to @samp{#t}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer doveadm-worker-count If non-zero, run mail commands via this many connections to doveadm server, instead of running them directly in the same process. Defaults to @samp{0}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string doveadm-socket-path UNIX socket or host:port used for connecting to doveadm server. Defaults to @samp{"doveadm-server"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list import-environment List of environment variables that are preserved on Dovecot startup and passed down to all of its child processes. You can also give key=value pairs to always set specific settings. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} boolean disable-plaintext-auth? Disable LOGIN command and all other plaintext authentications unless SSL/TLS is used (LOGINDISABLED capability). Note that if the remote IP matches the local IP (i.e.@: you're connecting from the same computer), the connection is considered secure and plaintext authentication is allowed. See also ssl=required setting. Defaults to @samp{#t}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer auth-cache-size Authentication cache size (e.g.@: @samp{#e10e6}). 0 means it's disabled. Note that bsdauth, PAM and vpopmail require @samp{cache-key} to be set for caching to be used. Defaults to @samp{0}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string auth-cache-ttl Time to live for cached data. After TTL expires the cached record is no longer used, *except* if the main database lookup returns internal failure. We also try to handle password changes automatically: If user's previous authentication was successful, but this one wasn't, the cache isn't used. For now this works only with plaintext authentication. Defaults to @samp{"1 hour"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string auth-cache-negative-ttl TTL for negative hits (user not found, password mismatch). 0 disables caching them completely. Defaults to @samp{"1 hour"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list auth-realms List of realms for SASL authentication mechanisms that need them. You can leave it empty if you don't want to support multiple realms. Many clients simply use the first one listed here, so keep the default realm first. Defaults to @samp{()}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string auth-default-realm Default realm/domain to use if none was specified. This is used for both SASL realms and appending @@domain to username in plaintext logins. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string auth-username-chars List of allowed characters in username. If the user-given username contains a character not listed in here, the login automatically fails. This is just an extra check to make sure user can't exploit any potential quote escaping vulnerabilities with SQL/LDAP databases. If you want to allow all characters, set this value to empty. Defaults to @samp{"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ01234567890.-_@@"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string auth-username-translation Username character translations before it's looked up from databases. The value contains series of from -> to characters. For example @samp{#@@/@@} means that @samp{#} and @samp{/} characters are translated to @samp{@@}. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string auth-username-format Username formatting before it's looked up from databases. You can use the standard variables here, e.g.@: %Lu would lowercase the username, %n would drop away the domain if it was given, or @samp{%n-AT-%d} would change the @samp{@@} into @samp{-AT-}. This translation is done after @samp{auth-username-translation} changes. Defaults to @samp{"%Lu"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string auth-master-user-separator If you want to allow master users to log in by specifying the master username within the normal username string (i.e.@: not using SASL mechanism's support for it), you can specify the separator character here. The format is then . UW-IMAP uses @samp{*} as the separator, so that could be a good choice. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string auth-anonymous-username Username to use for users logging in with ANONYMOUS SASL mechanism. Defaults to @samp{"anonymous"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer auth-worker-max-count Maximum number of dovecot-auth worker processes. They're used to execute blocking passdb and userdb queries (e.g.@: MySQL and PAM). They're automatically created and destroyed as needed. Defaults to @samp{30}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string auth-gssapi-hostname Host name to use in GSSAPI principal names. The default is to use the name returned by gethostname(). Use @samp{$ALL} (with quotes) to allow all keytab entries. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string auth-krb5-keytab Kerberos keytab to use for the GSSAPI mechanism. Will use the system default (usually @file{/etc/krb5.keytab}) if not specified. You may need to change the auth service to run as root to be able to read this file. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} boolean auth-use-winbind? Do NTLM and GSS-SPNEGO authentication using Samba's winbind daemon and @samp{ntlm-auth} helper. . Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} file-name auth-winbind-helper-path Path for Samba's @samp{ntlm-auth} helper binary. Defaults to @samp{"/usr/bin/ntlm_auth"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string auth-failure-delay Time to delay before replying to failed authentications. Defaults to @samp{"2 secs"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} boolean auth-ssl-require-client-cert? Require a valid SSL client certificate or the authentication fails. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} boolean auth-ssl-username-from-cert? Take the username from client's SSL certificate, using @code{X509_NAME_get_text_by_NID()} which returns the subject's DN's CommonName. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list auth-mechanisms List of wanted authentication mechanisms. Supported mechanisms are: @samp{plain}, @samp{login}, @samp{digest-md5}, @samp{cram-md5}, @samp{ntlm}, @samp{rpa}, @samp{apop}, @samp{anonymous}, @samp{gssapi}, @samp{otp}, @samp{skey}, and @samp{gss-spnego}. NOTE: See also @samp{disable-plaintext-auth} setting. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list director-servers List of IPs or hostnames to all director servers, including ourself. Ports can be specified as ip:port. The default port is the same as what director service's @samp{inet-listener} is using. Defaults to @samp{()}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list director-mail-servers List of IPs or hostnames to all backend mail servers. Ranges are allowed too, like 10.0.0.10-10.0.0.30. Defaults to @samp{()}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string director-user-expire How long to redirect users to a specific server after it no longer has any connections. Defaults to @samp{"15 min"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string director-username-hash How the username is translated before being hashed. Useful values include %Ln if user can log in with or without @@domain, %Ld if mailboxes are shared within domain. Defaults to @samp{"%Lu"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string log-path Log file to use for error messages. @samp{syslog} logs to syslog, @samp{/dev/stderr} logs to stderr. Defaults to @samp{"syslog"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string info-log-path Log file to use for informational messages. Defaults to @samp{log-path}. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string debug-log-path Log file to use for debug messages. Defaults to @samp{info-log-path}. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string syslog-facility Syslog facility to use if you're logging to syslog. Usually if you don't want to use @samp{mail}, you'll use local0..local7. Also other standard facilities are supported. Defaults to @samp{"mail"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} boolean auth-verbose? Log unsuccessful authentication attempts and the reasons why they failed. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string auth-verbose-passwords In case of password mismatches, log the attempted password. Valid values are no, plain and sha1. sha1 can be useful for detecting brute force password attempts vs. user simply trying the same password over and over again. You can also truncate the value to n chars by appending ":n" (e.g.@: sha1:6). Defaults to @samp{"no"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} boolean auth-debug? Even more verbose logging for debugging purposes. Shows for example SQL queries. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} boolean auth-debug-passwords? In case of password mismatches, log the passwords and used scheme so the problem can be debugged. Enabling this also enables @samp{auth-debug}. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} boolean mail-debug? Enable mail process debugging. This can help you figure out why Dovecot isn't finding your mails. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} boolean verbose-ssl? Show protocol level SSL errors. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string log-timestamp Prefix for each line written to log file. % codes are in strftime(3) format. Defaults to @samp{"\"%b %d %H:%M:%S \""}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list login-log-format-elements List of elements we want to log. The elements which have a non-empty variable value are joined together to form a comma-separated string. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string login-log-format Login log format. %s contains @samp{login-log-format-elements} string, %$ contains the data we want to log. Defaults to @samp{"%$: %s"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string mail-log-prefix Log prefix for mail processes. See doc/wiki/Variables.txt for list of possible variables you can use. Defaults to @samp{"\"%s(%u)<%@{pid@}><%@{session@}>: \""}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string deliver-log-format Format to use for logging mail deliveries. You can use variables: @table @code @item %$ Delivery status message (e.g.@: @samp{saved to INBOX}) @item %m Message-ID @item %s Subject @item %f From address @item %p Physical size @item %w Virtual size. @end table Defaults to @samp{"msgid=%m: %$"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string mail-location Location for users' mailboxes. The default is empty, which means that Dovecot tries to find the mailboxes automatically. This won't work if the user doesn't yet have any mail, so you should explicitly tell Dovecot the full location. If you're using mbox, giving a path to the INBOX file (e.g.@: @file{/var/mail/%u}) isn't enough. You'll also need to tell Dovecot where the other mailboxes are kept. This is called the @emph{root mail directory}, and it must be the first path given in the @samp{mail-location} setting. There are a few special variables you can use, e.g.: @table @samp @item %u username @item %n user part in user@@domain, same as %u if there's no domain @item %d domain part in user@@domain, empty if there's no domain @item %h home director @end table See doc/wiki/Variables.txt for full list. Some examples: @table @samp @item maildir:~/Maildir @item mbox:~/mail:INBOX=/var/mail/%u @item mbox:/var/mail/%d/%1n/%n:INDEX=/var/indexes/%d/%1n/% @end table Defaults to @samp{""}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string mail-uid System user and group used to access mails. If you use multiple, userdb can override these by returning uid or gid fields. You can use either numbers or names. . Defaults to @samp{""}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string mail-gid Defaults to @samp{""}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string mail-privileged-group Group to enable temporarily for privileged operations. Currently this is used only with INBOX when either its initial creation or dotlocking fails. Typically this is set to @samp{"mail"} to give access to @file{/var/mail}. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string mail-access-groups Grant access to these supplementary groups for mail processes. Typically these are used to set up access to shared mailboxes. Note that it may be dangerous to set these if users can create symlinks (e.g.@: if @samp{mail} group is set here, @code{ln -s /var/mail ~/mail/var} could allow a user to delete others' mailboxes, or @code{ln -s /secret/shared/box ~/mail/mybox} would allow reading it). Defaults to @samp{""}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} boolean mail-full-filesystem-access? Allow full file system access to clients. There's no access checks other than what the operating system does for the active UID/GID. It works with both maildir and mboxes, allowing you to prefix mailboxes names with e.g.@: @file{/path/} or @file{~user/}. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} boolean mmap-disable? Don't use @code{mmap()} at all. This is required if you store indexes to shared file systems (NFS or clustered file system). Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} boolean dotlock-use-excl? Rely on @samp{O_EXCL} to work when creating dotlock files. NFS supports @samp{O_EXCL} since version 3, so this should be safe to use nowadays by default. Defaults to @samp{#t}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string mail-fsync When to use fsync() or fdatasync() calls: @table @code @item optimized Whenever necessary to avoid losing important data @item always Useful with e.g.@: NFS when @code{write()}s are delayed @item never Never use it (best performance, but crashes can lose data). @end table Defaults to @samp{"optimized"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} boolean mail-nfs-storage? Mail storage exists in NFS. Set this to yes to make Dovecot flush NFS caches whenever needed. If you're using only a single mail server this isn't needed. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} boolean mail-nfs-index? Mail index files also exist in NFS. Setting this to yes requires @samp{mmap-disable? #t} and @samp{fsync-disable? #f}. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string lock-method Locking method for index files. Alternatives are fcntl, flock and dotlock. Dotlocking uses some tricks which may create more disk I/O than other locking methods. NFS users: flock doesn't work, remember to change @samp{mmap-disable}. Defaults to @samp{"fcntl"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} file-name mail-temp-dir Directory in which LDA/LMTP temporarily stores incoming mails >128 kB. Defaults to @samp{"/tmp"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer first-valid-uid Valid UID range for users. This is mostly to make sure that users can't log in as daemons or other system users. Note that denying root logins is hardcoded to dovecot binary and can't be done even if @samp{first-valid-uid} is set to 0. Defaults to @samp{500}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer last-valid-uid Defaults to @samp{0}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer first-valid-gid Valid GID range for users. Users having non-valid GID as primary group ID aren't allowed to log in. If user belongs to supplementary groups with non-valid GIDs, those groups are not set. Defaults to @samp{1}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer last-valid-gid Defaults to @samp{0}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mail-max-keyword-length Maximum allowed length for mail keyword name. It's only forced when trying to create new keywords. Defaults to @samp{50}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} colon-separated-file-name-list valid-chroot-dirs List of directories under which chrooting is allowed for mail processes (i.e.@: @file{/var/mail} will allow chrooting to @file{/var/mail/foo/bar} too). This setting doesn't affect @samp{login-chroot} @samp{mail-chroot} or auth chroot settings. If this setting is empty, @samp{/./} in home dirs are ignored. WARNING: Never add directories here which local users can modify, that may lead to root exploit. Usually this should be done only if you don't allow shell access for users. . Defaults to @samp{()}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string mail-chroot Default chroot directory for mail processes. This can be overridden for specific users in user database by giving @samp{/./} in user's home directory (e.g.@: @samp{/home/./user} chroots into @file{/home}). Note that usually there is no real need to do chrooting, Dovecot doesn't allow users to access files outside their mail directory anyway. If your home directories are prefixed with the chroot directory, append @samp{/.} to @samp{mail-chroot}. . Defaults to @samp{""}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} file-name auth-socket-path UNIX socket path to master authentication server to find users. This is used by imap (for shared users) and lda. Defaults to @samp{"/var/run/dovecot/auth-userdb"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} file-name mail-plugin-dir Directory where to look up mail plugins. Defaults to @samp{"/usr/lib/dovecot"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list mail-plugins List of plugins to load for all services. Plugins specific to IMAP, LDA, etc.@: are added to this list in their own .conf files. Defaults to @samp{()}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mail-cache-min-mail-count The minimum number of mails in a mailbox before updates are done to cache file. This allows optimizing Dovecot's behavior to do less disk writes at the cost of more disk reads. Defaults to @samp{0}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string mailbox-idle-check-interval When IDLE command is running, mailbox is checked once in a while to see if there are any new mails or other changes. This setting defines the minimum time to wait between those checks. Dovecot can also use dnotify, inotify and kqueue to find out immediately when changes occur. Defaults to @samp{"30 secs"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} boolean mail-save-crlf? Save mails with CR+LF instead of plain LF. This makes sending those mails take less CPU, especially with sendfile() syscall with Linux and FreeBSD. But it also creates a bit more disk I/O which may just make it slower. Also note that if other software reads the mboxes/maildirs, they may handle the extra CRs wrong and cause problems. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} boolean maildir-stat-dirs? By default LIST command returns all entries in maildir beginning with a dot. Enabling this option makes Dovecot return only entries which are directories. This is done by stat()ing each entry, so it causes more disk I/O. (For systems setting struct @samp{dirent->d_type} this check is free and it's done always regardless of this setting). Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} boolean maildir-copy-with-hardlinks? When copying a message, do it with hard links whenever possible. This makes the performance much better, and it's unlikely to have any side effects. Defaults to @samp{#t}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} boolean maildir-very-dirty-syncs? Assume Dovecot is the only MUA accessing Maildir: Scan cur/ directory only when its mtime changes unexpectedly or when we can't find the mail otherwise. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list mbox-read-locks Which locking methods to use for locking mbox. There are four available: @table @code @item dotlock Create .lock file. This is the oldest and most NFS-safe solution. If you want to use /var/mail/ like directory, the users will need write access to that directory. @item dotlock-try Same as dotlock, but if it fails because of permissions or because there isn't enough disk space, just skip it. @item fcntl Use this if possible. Works with NFS too if lockd is used. @item flock May not exist in all systems. Doesn't work with NFS. @item lockf May not exist in all systems. Doesn't work with NFS. @end table You can use multiple locking methods; if you do the order they're declared in is important to avoid deadlocks if other MTAs/MUAs are using multiple locking methods as well. Some operating systems don't allow using some of them simultaneously. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list mbox-write-locks @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string mbox-lock-timeout Maximum time to wait for lock (all of them) before aborting. Defaults to @samp{"5 mins"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string mbox-dotlock-change-timeout If dotlock exists but the mailbox isn't modified in any way, override the lock file after this much time. Defaults to @samp{"2 mins"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} boolean mbox-dirty-syncs? When mbox changes unexpectedly we have to fully read it to find out what changed. If the mbox is large this can take a long time. Since the change is usually just a newly appended mail, it'd be faster to simply read the new mails. If this setting is enabled, Dovecot does this but still safely fallbacks to re-reading the whole mbox file whenever something in mbox isn't how it's expected to be. The only real downside to this setting is that if some other MUA changes message flags, Dovecot doesn't notice it immediately. Note that a full sync is done with SELECT, EXAMINE, EXPUNGE and CHECK commands. Defaults to @samp{#t}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} boolean mbox-very-dirty-syncs? Like @samp{mbox-dirty-syncs}, but don't do full syncs even with SELECT, EXAMINE, EXPUNGE or CHECK commands. If this is set, @samp{mbox-dirty-syncs} is ignored. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} boolean mbox-lazy-writes? Delay writing mbox headers until doing a full write sync (EXPUNGE and CHECK commands and when closing the mailbox). This is especially useful for POP3 where clients often delete all mails. The downside is that our changes aren't immediately visible to other MUAs. Defaults to @samp{#t}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mbox-min-index-size If mbox size is smaller than this (e.g.@: 100k), don't write index files. If an index file already exists it's still read, just not updated. Defaults to @samp{0}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mdbox-rotate-size Maximum dbox file size until it's rotated. Defaults to @samp{10000000}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string mdbox-rotate-interval Maximum dbox file age until it's rotated. Typically in days. Day begins from midnight, so 1d = today, 2d = yesterday, etc. 0 = check disabled. Defaults to @samp{"1d"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} boolean mdbox-preallocate-space? When creating new mdbox files, immediately preallocate their size to @samp{mdbox-rotate-size}. This setting currently works only in Linux with some file systems (ext4, xfs). Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string mail-attachment-dir sdbox and mdbox support saving mail attachments to external files, which also allows single instance storage for them. Other backends don't support this for now. WARNING: This feature hasn't been tested much yet. Use at your own risk. Directory root where to store mail attachments. Disabled, if empty. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mail-attachment-min-size Attachments smaller than this aren't saved externally. It's also possible to write a plugin to disable saving specific attachments externally. Defaults to @samp{128000}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string mail-attachment-fs File system backend to use for saving attachments: @table @code @item posix No SiS done by Dovecot (but this might help FS's own deduplication) @item sis posix SiS with immediate byte-by-byte comparison during saving @item sis-queue posix SiS with delayed comparison and deduplication. @end table Defaults to @samp{"sis posix"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string mail-attachment-hash Hash format to use in attachment filenames. You can add any text and variables: @code{%@{md4@}}, @code{%@{md5@}}, @code{%@{sha1@}}, @code{%@{sha256@}}, @code{%@{sha512@}}, @code{%@{size@}}. Variables can be truncated, e.g.@: @code{%@{sha256:80@}} returns only first 80 bits. Defaults to @samp{"%@{sha1@}"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer default-process-limit Defaults to @samp{100}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer default-client-limit Defaults to @samp{1000}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer default-vsz-limit Default VSZ (virtual memory size) limit for service processes. This is mainly intended to catch and kill processes that leak memory before they eat up everything. Defaults to @samp{256000000}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string default-login-user Login user is internally used by login processes. This is the most untrusted user in Dovecot system. It shouldn't have access to anything at all. Defaults to @samp{"dovenull"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string default-internal-user Internal user is used by unprivileged processes. It should be separate from login user, so that login processes can't disturb other processes. Defaults to @samp{"dovecot"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string ssl? SSL/TLS support: yes, no, required. . Defaults to @samp{"required"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string ssl-cert PEM encoded X.509 SSL/TLS certificate (public key). Defaults to @samp{" was automatically rejected:%n%r"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string recipient-delimiter Delimiter character between local-part and detail in email address. Defaults to @samp{"+"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string lda-original-recipient-header Header where the original recipient address (SMTP's RCPT TO: address) is taken from if not available elsewhere. With dovecot-lda -a parameter overrides this. A commonly used header for this is X-Original-To. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} boolean lda-mailbox-autocreate? Should saving a mail to a nonexistent mailbox automatically create it?. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} boolean lda-mailbox-autosubscribe? Should automatically created mailboxes be also automatically subscribed?. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer imap-max-line-length Maximum IMAP command line length. Some clients generate very long command lines with huge mailboxes, so you may need to raise this if you get "Too long argument" or "IMAP command line too large" errors often. Defaults to @samp{64000}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string imap-logout-format IMAP logout format string: @table @code @item %i total number of bytes read from client @item %o total number of bytes sent to client. @end table See @file{doc/wiki/Variables.txt} for a list of all the variables you can use. Defaults to @samp{"in=%i out=%o deleted=%@{deleted@} expunged=%@{expunged@} trashed=%@{trashed@} hdr_count=%@{fetch_hdr_count@} hdr_bytes=%@{fetch_hdr_bytes@} body_count=%@{fetch_body_count@} body_bytes=%@{fetch_body_bytes@}"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string imap-capability Override the IMAP CAPABILITY response. If the value begins with '+', add the given capabilities on top of the defaults (e.g.@: +XFOO XBAR). Defaults to @samp{""}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string imap-idle-notify-interval How long to wait between "OK Still here" notifications when client is IDLEing. Defaults to @samp{"2 mins"}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string imap-id-send ID field names and values to send to clients. Using * as the value makes Dovecot use the default value. The following fields have default values currently: name, version, os, os-version, support-url, support-email. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} string imap-id-log ID fields sent by client to log. * means everything. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list imap-client-workarounds Workarounds for various client bugs: @table @code @item delay-newmail Send EXISTS/RECENT new mail notifications only when replying to NOOP and CHECK commands. Some clients ignore them otherwise, for example OSX Mail (' before setting it here, to get a feel for which cipher suites you will get. After setting this option, it is recommend that you inspect your Murmur log to ensure that Murmur is using the cipher suites that you expected it to. Note: Changing this option may impact the backwards compatibility of your Murmur server, and can remove the ability for older Mumble clients to be able to connect to it. @item @code{public-registration} (default: @code{#f}) Must be a @code{} record or @code{#f}. You can optionally register your server in the public server list that the @code{mumble} client shows on startup. You cannot register your server if you have set a @code{server-password}, or set @code{allow-ping} to @code{#f}. It might take a few hours until it shows up in the public list. @item @code{file} (default: @code{#f}) Optional alternative override for this configuration. @end table @end deftp @deftp {Data Type} murmur-public-registration-configuration Configuration for public registration of a murmur service. @table @asis @item @code{name} This is a display name for your server. Not to be confused with the hostname. @item @code{password} A password to identify your registration. Subsequent updates will need the same password. Don't lose your password. @item @code{url} This should be a @code{http://} or @code{https://} link to your web site. @item @code{hostname} (default: @code{#f}) By default your server will be listed by its IP address. If it is set your server will be linked by this host name instead. @end table @end deftp @node Monitoring Services @subsection Monitoring Services @subsubheading Tailon Service @uref{https://tailon.readthedocs.io/, Tailon} is a web application for viewing and searching log files. The following example will configure the service with default values. By default, Tailon can be accessed on port 8080 (@code{http://localhost:8080}). @lisp (service tailon-service-type) @end lisp The following example customises more of the Tailon configuration, adding @command{sed} to the list of allowed commands. @lisp (service tailon-service-type (tailon-configuration (config-file (tailon-configuration-file (allowed-commands '("tail" "grep" "awk" "sed")))))) @end lisp @deftp {Data Type} tailon-configuration Data type representing the configuration of Tailon. This type has the following parameters: @table @asis @item @code{config-file} (default: @code{(tailon-configuration-file)}) The configuration file to use for Tailon. This can be set to a @dfn{tailon-configuration-file} record value, or any gexp (@pxref{G-Expressions}). For example, to instead use a local file, the @code{local-file} function can be used: @lisp (service tailon-service-type (tailon-configuration (config-file (local-file "./my-tailon.conf")))) @end lisp @item @code{package} (default: @code{tailon}) The tailon package to use. @end table @end deftp @deftp {Data Type} tailon-configuration-file Data type representing the configuration options for Tailon. This type has the following parameters: @table @asis @item @code{files} (default: @code{(list "/var/log")}) List of files to display. The list can include strings for a single file or directory, or a list, where the first item is the name of a subsection, and the remaining items are the files or directories in that subsection. @item @code{bind} (default: @code{"localhost:8080"}) Address and port to which Tailon should bind on. @item @code{relative-root} (default: @code{#f}) URL path to use for Tailon, set to @code{#f} to not use a path. @item @code{allow-transfers?} (default: @code{#t}) Allow downloading the log files in the web interface. @item @code{follow-names?} (default: @code{#t}) Allow tailing of not-yet existent files. @item @code{tail-lines} (default: @code{200}) Number of lines to read initially from each file. @item @code{allowed-commands} (default: @code{(list "tail" "grep" "awk")}) Commands to allow running. By default, @code{sed} is disabled. @item @code{debug?} (default: @code{#f}) Set @code{debug?} to @code{#t} to show debug messages. @item @code{wrap-lines} (default: @code{#t}) Initial line wrapping state in the web interface. Set to @code{#t} to initially wrap lines (the default), or to @code{#f} to initially not wrap lines. @item @code{http-auth} (default: @code{#f}) HTTP authentication type to use. Set to @code{#f} to disable authentication (the default). Supported values are @code{"digest"} or @code{"basic"}. @item @code{users} (default: @code{#f}) If HTTP authentication is enabled (see @code{http-auth}), access will be restricted to the credentials provided here. To configure users, use a list of pairs, where the first element of the pair is the username, and the 2nd element of the pair is the password. @lisp (tailon-configuration-file (http-auth "basic") (users '(("user1" . "password1") ("user2" . "password2")))) @end lisp @end table @end deftp @subsubheading Darkstat Service @cindex darkstat Darkstat is a packet sniffer that captures network traffic, calculates statistics about usage, and serves reports over HTTP. @defvar {Scheme Variable} darkstat-service-type This is the service type for the @uref{https://unix4lyfe.org/darkstat/, darkstat} service, its value must be a @code{darkstat-configuration} record as in this example: @lisp (service darkstat-service-type (darkstat-configuration (interface "eno1"))) @end lisp @end defvar @deftp {Data Type} darkstat-configuration Data type representing the configuration of @command{darkstat}. @table @asis @item @code{package} (default: @code{darkstat}) The darkstat package to use. @item @code{interface} Capture traffic on the specified network interface. @item @code{port} (default: @code{"667"}) Bind the web interface to the specified port. @item @code{bind-address} (default: @code{"127.0.0.1"}) Bind the web interface to the specified address. @item @code{base} (default: @code{"/"}) Specify the path of the base URL. This can be useful if @command{darkstat} is accessed via a reverse proxy. @end table @end deftp @subsubheading Prometheus Node Exporter Service @cindex prometheus-node-exporter The Prometheus ``node exporter'' makes hardware and operating system statistics provided by the Linux kernel available for the Prometheus monitoring system. This service should be deployed on all physical nodes and virtual machines, where monitoring these statistics is desirable. @defvar {Scheme variable} prometheus-node-exporter-service-type This is the service type for the @uref{https://github.com/prometheus/node_exporter/, prometheus-node-exporter} service, its value must be a @code{prometheus-node-exporter-configuration}. @lisp (service prometheus-node-exporter-service-type) @end lisp @end defvar @deftp {Data Type} prometheus-node-exporter-configuration Data type representing the configuration of @command{node_exporter}. @table @asis @item @code{package} (default: @code{go-github-com-prometheus-node-exporter}) The prometheus-node-exporter package to use. @item @code{web-listen-address} (default: @code{":9100"}) Bind the web interface to the specified address. @item @code{textfile-directory} (default: @code{"/var/lib/prometheus/node-exporter"}) This directory can be used to export metrics specific to this machine. Files containing metrics in the text format, with the filename ending in @code{.prom} should be placed in this directory. @item @code{extra-options} (default: @code{'()}) Extra options to pass to the Prometheus node exporter. @end table @end deftp @subsubheading Zabbix server @cindex zabbix zabbix-server Zabbix provides monitoring metrics, among others network utilization, CPU load and disk space consumption: @itemize @item High performance, high capacity (able to monitor hundreds of thousands of devices). @item Auto-discovery of servers and network devices and interfaces. @item Low-level discovery, allows to automatically start monitoring new items, file systems or network interfaces among others. @item Distributed monitoring with centralized web administration. @item Native high performance agents. @item SLA, and ITIL KPI metrics on reporting. @item High-level (business) view of monitored resources through user-defined visual console screens and dashboards. @item Remote command execution through Zabbix proxies. @end itemize @c %start of fragment Available @code{zabbix-server-configuration} fields are: @deftypevr {@code{zabbix-server-configuration} parameter} package zabbix-server The zabbix-server package. @end deftypevr @deftypevr {@code{zabbix-server-configuration} parameter} string user User who will run the Zabbix server. Defaults to @samp{"zabbix"}. @end deftypevr @deftypevr {@code{zabbix-server-configuration} parameter} group group Group who will run the Zabbix server. Defaults to @samp{"zabbix"}. @end deftypevr @deftypevr {@code{zabbix-server-configuration} parameter} string db-host Database host name. Defaults to @samp{"127.0.0.1"}. @end deftypevr @deftypevr {@code{zabbix-server-configuration} parameter} string db-name Database name. Defaults to @samp{"zabbix"}. @end deftypevr @deftypevr {@code{zabbix-server-configuration} parameter} string db-user Database user. Defaults to @samp{"zabbix"}. @end deftypevr @deftypevr {@code{zabbix-server-configuration} parameter} string db-password Database password. Please, use @code{include-files} with @code{DBPassword=SECRET} inside a specified file instead. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{zabbix-server-configuration} parameter} number db-port Database port. Defaults to @samp{5432}. @end deftypevr @deftypevr {@code{zabbix-server-configuration} parameter} string log-type Specifies where log messages are written to: @itemize @bullet @item @code{system} - syslog. @item @code{file} - file specified with @code{log-file} parameter. @item @code{console} - standard output. @end itemize Defaults to @samp{""}. @end deftypevr @deftypevr {@code{zabbix-server-configuration} parameter} string log-file Log file name for @code{log-type} @code{file} parameter. Defaults to @samp{"/var/log/zabbix/server.log"}. @end deftypevr @deftypevr {@code{zabbix-server-configuration} parameter} string pid-file Name of PID file. Defaults to @samp{"/var/run/zabbix/zabbix_server.pid"}. @end deftypevr @deftypevr {@code{zabbix-server-configuration} parameter} string ssl-ca-location The location of certificate authority (CA) files for SSL server certificate verification. Defaults to @samp{"/etc/ssl/certs/ca-certificates.crt"}. @end deftypevr @deftypevr {@code{zabbix-server-configuration} parameter} string ssl-cert-location Location of SSL client certificates. Defaults to @samp{"/etc/ssl/certs"}. @end deftypevr @deftypevr {@code{zabbix-server-configuration} parameter} string extra-options Extra options will be appended to Zabbix server configuration file. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{zabbix-server-configuration} parameter} include-files include-files You may include individual files or all files in a directory in the configuration file. Defaults to @samp{()}. @end deftypevr @c %end of fragment @subsubheading Zabbix agent @cindex zabbix zabbix-agent Zabbix agent gathers information for Zabbix server. @c %start of fragment Available @code{zabbix-agent-configuration} fields are: @deftypevr {@code{zabbix-agent-configuration} parameter} package zabbix-agent The zabbix-agent package. @end deftypevr @deftypevr {@code{zabbix-agent-configuration} parameter} string user User who will run the Zabbix agent. Defaults to @samp{"zabbix"}. @end deftypevr @deftypevr {@code{zabbix-agent-configuration} parameter} group group Group who will run the Zabbix agent. Defaults to @samp{"zabbix"}. @end deftypevr @deftypevr {@code{zabbix-agent-configuration} parameter} string hostname Unique, case sensitive hostname which is required for active checks and must match hostname as configured on the server. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{zabbix-agent-configuration} parameter} string log-type Specifies where log messages are written to: @itemize @bullet @item @code{system} - syslog. @item @code{file} - file specified with @code{log-file} parameter. @item @code{console} - standard output. @end itemize Defaults to @samp{""}. @end deftypevr @deftypevr {@code{zabbix-agent-configuration} parameter} string log-file Log file name for @code{log-type} @code{file} parameter. Defaults to @samp{"/var/log/zabbix/agent.log"}. @end deftypevr @deftypevr {@code{zabbix-agent-configuration} parameter} string pid-file Name of PID file. Defaults to @samp{"/var/run/zabbix/zabbix_agent.pid"}. @end deftypevr @deftypevr {@code{zabbix-agent-configuration} parameter} list server List of IP addresses, optionally in CIDR notation, or hostnames of Zabbix servers and Zabbix proxies. Incoming connections will be accepted only from the hosts listed here. Defaults to @samp{("127.0.0.1")}. @end deftypevr @deftypevr {@code{zabbix-agent-configuration} parameter} list server-active List of IP:port (or hostname:port) pairs of Zabbix servers and Zabbix proxies for active checks. If port is not specified, default port is used. If this parameter is not specified, active checks are disabled. Defaults to @samp{("127.0.0.1")}. @end deftypevr @deftypevr {@code{zabbix-agent-configuration} parameter} string extra-options Extra options will be appended to Zabbix server configuration file. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{zabbix-agent-configuration} parameter} include-files include-files You may include individual files or all files in a directory in the configuration file. Defaults to @samp{()}. @end deftypevr @c %end of fragment @subsubheading Zabbix front-end @cindex zabbix zabbix-front-end This service provides a WEB interface to Zabbix server. @c %start of fragment Available @code{zabbix-front-end-configuration} fields are: @deftypevr {@code{zabbix-front-end-configuration} parameter} nginx-server-configuration-list nginx NGINX configuration. @end deftypevr @deftypevr {@code{zabbix-front-end-configuration} parameter} string db-host Database host name. Defaults to @samp{"localhost"}. @end deftypevr @deftypevr {@code{zabbix-front-end-configuration} parameter} number db-port Database port. Defaults to @samp{5432}. @end deftypevr @deftypevr {@code{zabbix-front-end-configuration} parameter} string db-name Database name. Defaults to @samp{"zabbix"}. @end deftypevr @deftypevr {@code{zabbix-front-end-configuration} parameter} string db-user Database user. Defaults to @samp{"zabbix"}. @end deftypevr @deftypevr {@code{zabbix-front-end-configuration} parameter} string db-password Database password. Please, use @code{db-secret-file} instead. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{zabbix-front-end-configuration} parameter} string db-secret-file Secret file containing the credentials for the Zabbix front-end. The value must be a local file name, not a G-expression. You are expected to create this file manually. Its contents will be copied into @file{zabbix.conf.php} as the value of @code{$DB['PASSWORD']}. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{zabbix-front-end-configuration} parameter} string zabbix-host Zabbix server hostname. Defaults to @samp{"localhost"}. @end deftypevr @deftypevr {@code{zabbix-front-end-configuration} parameter} number zabbix-port Zabbix server port. Defaults to @samp{10051}. @end deftypevr @c %end of fragment @node Kerberos Services @subsection Kerberos Services @cindex Kerberos The @code{(gnu services kerberos)} module provides services relating to the authentication protocol @dfn{Kerberos}. @subsubheading Krb5 Service Programs using a Kerberos client library normally expect a configuration file in @file{/etc/krb5.conf}. This service generates such a file from a definition provided in the operating system declaration. It does not cause any daemon to be started. No ``keytab'' files are provided by this service---you must explicitly create them. This service is known to work with the MIT client library, @code{mit-krb5}. Other implementations have not been tested. @defvr {Scheme Variable} krb5-service-type A service type for Kerberos 5 clients. @end defvr @noindent Here is an example of its use: @lisp (service krb5-service-type (krb5-configuration (default-realm "EXAMPLE.COM") (allow-weak-crypto? #t) (realms (list (krb5-realm (name "EXAMPLE.COM") (admin-server "groucho.example.com") (kdc "karl.example.com")) (krb5-realm (name "ARGRX.EDU") (admin-server "kerb-admin.argrx.edu") (kdc "keys.argrx.edu")))))) @end lisp @noindent This example provides a Kerberos@tie{}5 client configuration which: @itemize @item Recognizes two realms, @i{viz:} ``EXAMPLE.COM'' and ``ARGRX.EDU'', both of which have distinct administration servers and key distribution centers; @item Will default to the realm ``EXAMPLE.COM'' if the realm is not explicitly specified by clients; @item Accepts services which only support encryption types known to be weak. @end itemize The @code{krb5-realm} and @code{krb5-configuration} types have many fields. Only the most commonly used ones are described here. For a full list, and more detailed explanation of each, see the MIT @uref{https://web.mit.edu/kerberos/krb5-devel/doc/admin/conf_files/krb5_conf.html,,krb5.conf} documentation. @deftp {Data Type} krb5-realm @cindex realm, kerberos @table @asis @item @code{name} This field is a string identifying the name of the realm. A common convention is to use the fully qualified DNS name of your organization, converted to upper case. @item @code{admin-server} This field is a string identifying the host where the administration server is running. @item @code{kdc} This field is a string identifying the key distribution center for the realm. @end table @end deftp @deftp {Data Type} krb5-configuration @table @asis @item @code{allow-weak-crypto?} (default: @code{#f}) If this flag is @code{#t} then services which only offer encryption algorithms known to be weak will be accepted. @item @code{default-realm} (default: @code{#f}) This field should be a string identifying the default Kerberos realm for the client. You should set this field to the name of your Kerberos realm. If this value is @code{#f} then a realm must be specified with every Kerberos principal when invoking programs such as @command{kinit}. @item @code{realms} This should be a non-empty list of @code{krb5-realm} objects, which clients may access. Normally, one of them will have a @code{name} field matching the @code{default-realm} field. @end table @end deftp @subsubheading PAM krb5 Service @cindex pam-krb5 The @code{pam-krb5} service allows for login authentication and password management via Kerberos. You will need this service if you want PAM enabled applications to authenticate users using Kerberos. @defvr {Scheme Variable} pam-krb5-service-type A service type for the Kerberos 5 PAM module. @end defvr @deftp {Data Type} pam-krb5-configuration Data type representing the configuration of the Kerberos 5 PAM module. This type has the following parameters: @table @asis @item @code{pam-krb5} (default: @code{pam-krb5}) The pam-krb5 package to use. @item @code{minimum-uid} (default: @code{1000}) The smallest user ID for which Kerberos authentications should be attempted. Local accounts with lower values will silently fail to authenticate. @end table @end deftp @node LDAP Services @subsection LDAP Services @cindex LDAP @cindex nslcd, LDAP service The @code{(gnu services authentication)} module provides the @code{nslcd-service-type}, which can be used to authenticate against an LDAP server. In addition to configuring the service itself, you may want to add @code{ldap} as a name service to the Name Service Switch. @xref{Name Service Switch} for detailed information. Here is a simple operating system declaration with a default configuration of the @code{nslcd-service-type} and a Name Service Switch configuration that consults the @code{ldap} name service last: @lisp (use-service-modules authentication) (use-modules (gnu system nss)) ... (operating-system ... (services (cons* (service nslcd-service-type) (service dhcp-client-service-type) %base-services)) (name-service-switch (let ((services (list (name-service (name "db")) (name-service (name "files")) (name-service (name "ldap"))))) (name-service-switch (inherit %mdns-host-lookup-nss) (password services) (shadow services) (group services) (netgroup services) (gshadow services))))) @end lisp @c %start of generated documentation for nslcd-configuration Available @code{nslcd-configuration} fields are: @deftypevr {@code{nslcd-configuration} parameter} package nss-pam-ldapd The @code{nss-pam-ldapd} package to use. @end deftypevr @deftypevr {@code{nslcd-configuration} parameter} maybe-number threads The number of threads to start that can handle requests and perform LDAP queries. Each thread opens a separate connection to the LDAP server. The default is to start 5 threads. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{nslcd-configuration} parameter} string uid This specifies the user id with which the daemon should be run. Defaults to @samp{"nslcd"}. @end deftypevr @deftypevr {@code{nslcd-configuration} parameter} string gid This specifies the group id with which the daemon should be run. Defaults to @samp{"nslcd"}. @end deftypevr @deftypevr {@code{nslcd-configuration} parameter} log-option log This option controls the way logging is done via a list containing SCHEME and LEVEL. The SCHEME argument may either be the symbols @samp{none} or @samp{syslog}, or an absolute file name. The LEVEL argument is optional and specifies the log level. The log level may be one of the following symbols: @samp{crit}, @samp{error}, @samp{warning}, @samp{notice}, @samp{info} or @samp{debug}. All messages with the specified log level or higher are logged. Defaults to @samp{("/var/log/nslcd" info)}. @end deftypevr @deftypevr {@code{nslcd-configuration} parameter} list uri The list of LDAP server URIs. Normally, only the first server will be used with the following servers as fall-back. Defaults to @samp{("ldap://localhost:389/")}. @end deftypevr @deftypevr {@code{nslcd-configuration} parameter} maybe-string ldap-version The version of the LDAP protocol to use. The default is to use the maximum version supported by the LDAP library. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{nslcd-configuration} parameter} maybe-string binddn Specifies the distinguished name with which to bind to the directory server for lookups. The default is to bind anonymously. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{nslcd-configuration} parameter} maybe-string bindpw Specifies the credentials with which to bind. This option is only applicable when used with binddn. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{nslcd-configuration} parameter} maybe-string rootpwmoddn Specifies the distinguished name to use when the root user tries to modify a user's password using the PAM module. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{nslcd-configuration} parameter} maybe-string rootpwmodpw Specifies the credentials with which to bind if the root user tries to change a user's password. This option is only applicable when used with rootpwmoddn Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{nslcd-configuration} parameter} maybe-string sasl-mech Specifies the SASL mechanism to be used when performing SASL authentication. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{nslcd-configuration} parameter} maybe-string sasl-realm Specifies the SASL realm to be used when performing SASL authentication. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{nslcd-configuration} parameter} maybe-string sasl-authcid Specifies the authentication identity to be used when performing SASL authentication. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{nslcd-configuration} parameter} maybe-string sasl-authzid Specifies the authorization identity to be used when performing SASL authentication. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{nslcd-configuration} parameter} maybe-boolean sasl-canonicalize? Determines whether the LDAP server host name should be canonicalised. If this is enabled the LDAP library will do a reverse host name lookup. By default, it is left up to the LDAP library whether this check is performed or not. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{nslcd-configuration} parameter} maybe-string krb5-ccname Set the name for the GSS-API Kerberos credentials cache. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{nslcd-configuration} parameter} string base The directory search base. Defaults to @samp{"dc=example,dc=com"}. @end deftypevr @deftypevr {@code{nslcd-configuration} parameter} scope-option scope Specifies the search scope (subtree, onelevel, base or children). The default scope is subtree; base scope is almost never useful for name service lookups; children scope is not supported on all servers. Defaults to @samp{(subtree)}. @end deftypevr @deftypevr {@code{nslcd-configuration} parameter} maybe-deref-option deref Specifies the policy for dereferencing aliases. The default policy is to never dereference aliases. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{nslcd-configuration} parameter} maybe-boolean referrals Specifies whether automatic referral chasing should be enabled. The default behaviour is to chase referrals. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{nslcd-configuration} parameter} list-of-map-entries maps This option allows for custom attributes to be looked up instead of the default RFC 2307 attributes. It is a list of maps, each consisting of the name of a map, the RFC 2307 attribute to match and the query expression for the attribute as it is available in the directory. Defaults to @samp{()}. @end deftypevr @deftypevr {@code{nslcd-configuration} parameter} list-of-filter-entries filters A list of filters consisting of the name of a map to which the filter applies and an LDAP search filter expression. Defaults to @samp{()}. @end deftypevr @deftypevr {@code{nslcd-configuration} parameter} maybe-number bind-timelimit Specifies the time limit in seconds to use when connecting to the directory server. The default value is 10 seconds. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{nslcd-configuration} parameter} maybe-number timelimit Specifies the time limit (in seconds) to wait for a response from the LDAP server. A value of zero, which is the default, is to wait indefinitely for searches to be completed. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{nslcd-configuration} parameter} maybe-number idle-timelimit Specifies the period if inactivity (in seconds) after which the con‐ nection to the LDAP server will be closed. The default is not to time out connections. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{nslcd-configuration} parameter} maybe-number reconnect-sleeptime Specifies the number of seconds to sleep when connecting to all LDAP servers fails. By default one second is waited between the first failure and the first retry. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{nslcd-configuration} parameter} maybe-number reconnect-retrytime Specifies the time after which the LDAP server is considered to be permanently unavailable. Once this time is reached retries will be done only once per this time period. The default value is 10 seconds. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{nslcd-configuration} parameter} maybe-ssl-option ssl Specifies whether to use SSL/TLS or not (the default is not to). If 'start-tls is specified then StartTLS is used rather than raw LDAP over SSL. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{nslcd-configuration} parameter} maybe-tls-reqcert-option tls-reqcert Specifies what checks to perform on a server-supplied certificate. The meaning of the values is described in the ldap.conf(5) manual page. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{nslcd-configuration} parameter} maybe-string tls-cacertdir Specifies the directory containing X.509 certificates for peer authen‐ tication. This parameter is ignored when using GnuTLS. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{nslcd-configuration} parameter} maybe-string tls-cacertfile Specifies the path to the X.509 certificate for peer authentication. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{nslcd-configuration} parameter} maybe-string tls-randfile Specifies the path to an entropy source. This parameter is ignored when using GnuTLS. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{nslcd-configuration} parameter} maybe-string tls-ciphers Specifies the ciphers to use for TLS as a string. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{nslcd-configuration} parameter} maybe-string tls-cert Specifies the path to the file containing the local certificate for client TLS authentication. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{nslcd-configuration} parameter} maybe-string tls-key Specifies the path to the file containing the private key for client TLS authentication. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{nslcd-configuration} parameter} maybe-number pagesize Set this to a number greater than 0 to request paged results from the LDAP server in accordance with RFC2696. The default (0) is to not request paged results. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{nslcd-configuration} parameter} maybe-ignore-users-option nss-initgroups-ignoreusers This option prevents group membership lookups through LDAP for the specified users. Alternatively, the value 'all-local may be used. With that value nslcd builds a full list of non-LDAP users on startup. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{nslcd-configuration} parameter} maybe-number nss-min-uid This option ensures that LDAP users with a numeric user id lower than the specified value are ignored. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{nslcd-configuration} parameter} maybe-number nss-uid-offset This option specifies an offset that is added to all LDAP numeric user ids. This can be used to avoid user id collisions with local users. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{nslcd-configuration} parameter} maybe-number nss-gid-offset This option specifies an offset that is added to all LDAP numeric group ids. This can be used to avoid user id collisions with local groups. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{nslcd-configuration} parameter} maybe-boolean nss-nested-groups If this option is set, the member attribute of a group may point to another group. Members of nested groups are also returned in the higher level group and parent groups are returned when finding groups for a specific user. The default is not to perform extra searches for nested groups. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{nslcd-configuration} parameter} maybe-boolean nss-getgrent-skipmembers If this option is set, the group member list is not retrieved when looking up groups. Lookups for finding which groups a user belongs to will remain functional so the user will likely still get the correct groups assigned on login. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{nslcd-configuration} parameter} maybe-boolean nss-disable-enumeration If this option is set, functions which cause all user/group entries to be loaded from the directory will not succeed in doing so. This can dramatically reduce LDAP server load in situations where there are a great number of users and/or groups. This option is not recommended for most configurations. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{nslcd-configuration} parameter} maybe-string validnames This option can be used to specify how user and group names are verified within the system. This pattern is used to check all user and group names that are requested and returned from LDAP. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{nslcd-configuration} parameter} maybe-boolean ignorecase This specifies whether or not to perform searches using case-insensitive matching. Enabling this could open up the system to authorization bypass vulnerabilities and introduce nscd cache poisoning vulnerabilities which allow denial of service. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{nslcd-configuration} parameter} maybe-boolean pam-authc-ppolicy This option specifies whether password policy controls are requested and handled from the LDAP server when performing user authentication. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{nslcd-configuration} parameter} maybe-string pam-authc-search By default nslcd performs an LDAP search with the user's credentials after BIND (authentication) to ensure that the BIND operation was successful. The default search is a simple check to see if the user's DN exists. A search filter can be specified that will be used instead. It should return at least one entry. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{nslcd-configuration} parameter} maybe-string pam-authz-search This option allows flexible fine tuning of the authorisation check that should be performed. The search filter specified is executed and if any entries match, access is granted, otherwise access is denied. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{nslcd-configuration} parameter} maybe-string pam-password-prohibit-message If this option is set password modification using pam_ldap will be denied and the specified message will be presented to the user instead. The message can be used to direct the user to an alternative means of changing their password. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{nslcd-configuration} parameter} list pam-services List of pam service names for which LDAP authentication should suffice. Defaults to @samp{()}. @end deftypevr @c %end of generated documentation for nslcd-configuration @node Web Services @subsection Web Services @cindex web @cindex www @cindex HTTP The @code{(gnu services web)} module provides the Apache HTTP Server, the nginx web server, and also a fastcgi wrapper daemon. @subsubheading Apache HTTP Server @deffn {Scheme Variable} httpd-service-type Service type for the @uref{https://httpd.apache.org/,Apache HTTP} server (@dfn{httpd}). The value for this service type is a @code{httpd-configuration} record. A simple example configuration is given below. @lisp (service httpd-service-type (httpd-configuration (config (httpd-config-file (server-name "www.example.com") (document-root "/srv/http/www.example.com"))))) @end lisp Other services can also extend the @code{httpd-service-type} to add to the configuration. @lisp (simple-service 'www.example.com-server httpd-service-type (list (httpd-virtualhost "*:80" (list (string-join '("ServerName www.example.com" "DocumentRoot /srv/http/www.example.com") "\n"))))) @end lisp @end deffn The details for the @code{httpd-configuration}, @code{httpd-module}, @code{httpd-config-file} and @code{httpd-virtualhost} record types are given below. @deffn {Data Type} httpd-configuration This data type represents the configuration for the httpd service. @table @asis @item @code{package} (default: @code{httpd}) The httpd package to use. @item @code{pid-file} (default: @code{"/var/run/httpd"}) The pid file used by the shepherd-service. @item @code{config} (default: @code{(httpd-config-file)}) The configuration file to use with the httpd service. The default value is a @code{httpd-config-file} record, but this can also be a different G-expression that generates a file, for example a @code{plain-file}. A file outside of the store can also be specified through a string. @end table @end deffn @deffn {Data Type} httpd-module This data type represents a module for the httpd service. @table @asis @item @code{name} The name of the module. @item @code{file} The file for the module. This can be relative to the httpd package being used, the absolute location of a file, or a G-expression for a file within the store, for example @code{(file-append mod-wsgi "/modules/mod_wsgi.so")}. @end table @end deffn @defvr {Scheme Variable} %default-httpd-modules A default list of @code{httpd-module} objects. @end defvr @deffn {Data Type} httpd-config-file This data type represents a configuration file for the httpd service. @table @asis @item @code{modules} (default: @code{%default-httpd-modules}) The modules to load. Additional modules can be added here, or loaded by additional configuration. For example, in order to handle requests for PHP files, you can use Apache’s @code{mod_proxy_fcgi} module along with @code{php-fpm-service-type}: @lisp (service httpd-service-type (httpd-configuration (config (httpd-config-file (modules (cons* (httpd-module (name "proxy_module") (file "modules/mod_proxy.so")) (httpd-module (name "proxy_fcgi_module") (file "modules/mod_proxy_fcgi.so")) %default-httpd-modules)) (extra-config (list "\ SetHandler \"proxy:unix:/var/run/php-fpm.sock|fcgi://localhost/\" ")))))) (service php-fpm-service-type (php-fpm-configuration (socket "/var/run/php-fpm.sock") (socket-group "httpd"))) @end lisp @item @code{server-root} (default: @code{httpd}) The @code{ServerRoot} in the configuration file, defaults to the httpd package. Directives including @code{Include} and @code{LoadModule} are taken as relative to the server root. @item @code{server-name} (default: @code{#f}) The @code{ServerName} in the configuration file, used to specify the request scheme, hostname and port that the server uses to identify itself. This doesn't need to be set in the server config, and can be specified in virtual hosts. The default is @code{#f} to not specify a @code{ServerName}. @item @code{document-root} (default: @code{"/srv/http"}) The @code{DocumentRoot} from which files will be served. @item @code{listen} (default: @code{'("80")}) The list of values for the @code{Listen} directives in the config file. The value should be a list of strings, when each string can specify the port number to listen on, and optionally the IP address and protocol to use. @item @code{pid-file} (default: @code{"/var/run/httpd"}) The @code{PidFile} to use. This should match the @code{pid-file} set in the @code{httpd-configuration} so that the Shepherd service is configured correctly. @item @code{error-log} (default: @code{"/var/log/httpd/error_log"}) The @code{ErrorLog} to which the server will log errors. @item @code{user} (default: @code{"httpd"}) The @code{User} which the server will answer requests as. @item @code{group} (default: @code{"httpd"}) The @code{Group} which the server will answer requests as. @item @code{extra-config} (default: @code{(list "TypesConfig etc/httpd/mime.types")}) A flat list of strings and G-expressions which will be added to the end of the configuration file. Any values which the service is extended with will be appended to this list. @end table @end deffn @deffn {Data Type} httpd-virtualhost This data type represents a virtualhost configuration block for the httpd service. These should be added to the extra-config for the httpd-service. @lisp (simple-service 'www.example.com-server httpd-service-type (list (httpd-virtualhost "*:80" (list (string-join '("ServerName www.example.com" "DocumentRoot /srv/http/www.example.com") "\n"))))) @end lisp @table @asis @item @code{addresses-and-ports} The addresses and ports for the @code{VirtualHost} directive. @item @code{contents} The contents of the @code{VirtualHost} directive, this should be a list of strings and G-expressions. @end table @end deffn @subsubheading NGINX @deffn {Scheme Variable} nginx-service-type Service type for the @uref{https://nginx.org/,NGinx} web server. The value for this service type is a @code{} record. A simple example configuration is given below. @lisp (service nginx-service-type (nginx-configuration (server-blocks (list (nginx-server-configuration (server-name '("www.example.com")) (root "/srv/http/www.example.com")))))) @end lisp In addition to adding server blocks to the service configuration directly, this service can be extended by other services to add server blocks, as in this example: @lisp (simple-service 'my-extra-server nginx-service-type (list (nginx-server-configuration (root "/srv/http/extra-website") (try-files (list "$uri" "$uri/index.html"))))) @end lisp @end deffn At startup, @command{nginx} has not yet read its configuration file, so it uses a default file to log error messages. If it fails to load its configuration file, that is where error messages are logged. After the configuration file is loaded, the default error log file changes as per configuration. In our case, startup error messages can be found in @file{/var/run/nginx/logs/error.log}, and after configuration in @file{/var/log/nginx/error.log}. The second location can be changed with the @var{log-directory} configuration option. @deffn {Data Type} nginx-configuration This data type represents the configuration for NGinx. Some configuration can be done through this and the other provided record types, or alternatively, a config file can be provided. @table @asis @item @code{nginx} (default: @code{nginx}) The nginx package to use. @item @code{log-directory} (default: @code{"/var/log/nginx"}) The directory to which NGinx will write log files. @item @code{run-directory} (default: @code{"/var/run/nginx"}) The directory in which NGinx will create a pid file, and write temporary files. @item @code{server-blocks} (default: @code{'()}) A list of @dfn{server blocks} to create in the generated configuration file, the elements should be of type @code{}. The following example would setup NGinx to serve @code{www.example.com} from the @code{/srv/http/www.example.com} directory, without using HTTPS. @lisp (service nginx-service-type (nginx-configuration (server-blocks (list (nginx-server-configuration (server-name '("www.example.com")) (root "/srv/http/www.example.com")))))) @end lisp @item @code{upstream-blocks} (default: @code{'()}) A list of @dfn{upstream blocks} to create in the generated configuration file, the elements should be of type @code{}. Configuring upstreams through the @code{upstream-blocks} can be useful when combined with @code{locations} in the @code{} records. The following example creates a server configuration with one location configuration, that will proxy requests to a upstream configuration, which will handle requests with two servers. @lisp (service nginx-service-type (nginx-configuration (server-blocks (list (nginx-server-configuration (server-name '("www.example.com")) (root "/srv/http/www.example.com") (locations (list (nginx-location-configuration (uri "/path1") (body '("proxy_pass http://server-proxy;")))))))) (upstream-blocks (list (nginx-upstream-configuration (name "server-proxy") (servers (list "server1.example.com" "server2.example.com"))))))) @end lisp @item @code{file} (default: @code{#f}) If a configuration @var{file} is provided, this will be used, rather than generating a configuration file from the provided @code{log-directory}, @code{run-directory}, @code{server-blocks} and @code{upstream-blocks}. For proper operation, these arguments should match what is in @var{file} to ensure that the directories are created when the service is activated. This can be useful if you have an existing configuration file, or it's not possible to do what is required through the other parts of the nginx-configuration record. @item @code{server-names-hash-bucket-size} (default: @code{#f}) Bucket size for the server names hash tables, defaults to @code{#f} to use the size of the processors cache line. @item @code{server-names-hash-bucket-max-size} (default: @code{#f}) Maximum bucket size for the server names hash tables. @item @code{modules} (default: @code{'()}) List of nginx dynamic modules to load. This should be a list of file names of loadable modules, as in this example: @lisp (modules (list (file-append nginx-accept-language-module "\ /etc/nginx/modules/ngx_http_accept_language_module.so") (file-append nginx-lua-module "\ /etc/nginx/modules/ngx_http_lua_module.so"))) @end lisp @item @code{lua-package-path} (default: @code{'()}) List of nginx lua packages to load. This should be a list of package names of loadable lua modules, as in this example: @lisp (lua-package-path (list lua-resty-core lua-resty-lrucache lua-resty-signal lua-tablepool lua-resty-shell)) @end lisp @item @code{lua-package-cpath} (default: @code{'()}) List of nginx lua C packages to load. This should be a list of package names of loadable lua C modules, as in this example: @lisp (lua-package-cpath (list lua-resty-signal)) @end lisp @item @code{global-directives} (default: @code{'((events . ()))}) Association list of global directives for the top level of the nginx configuration. Values may themselves be association lists. @lisp (global-directives `((worker_processes . 16) (pcre_jit . on) (events . ((worker_connections . 1024))))) @end lisp @item @code{extra-content} (default: @code{""}) Extra content for the @code{http} block. Should be string or a string valued G-expression. @end table @end deffn @deftp {Data Type} nginx-server-configuration Data type representing the configuration of an nginx server block. This type has the following parameters: @table @asis @item @code{listen} (default: @code{'("80" "443 ssl")}) Each @code{listen} directive sets the address and port for IP, or the path for a UNIX-domain socket on which the server will accept requests. Both address and port, or only address or only port can be specified. An address may also be a hostname, for example: @lisp '("127.0.0.1:8000" "127.0.0.1" "8000" "*:8000" "localhost:8000") @end lisp @item @code{server-name} (default: @code{(list 'default)}) A list of server names this server represents. @code{'default} represents the default server for connections matching no other server. @item @code{root} (default: @code{"/srv/http"}) Root of the website nginx will serve. @item @code{locations} (default: @code{'()}) A list of @dfn{nginx-location-configuration} or @dfn{nginx-named-location-configuration} records to use within this server block. @item @code{index} (default: @code{(list "index.html")}) Index files to look for when clients ask for a directory. If it cannot be found, Nginx will send the list of files in the directory. @item @code{try-files} (default: @code{'()}) A list of files whose existence is checked in the specified order. @code{nginx} will use the first file it finds to process the request. @item @code{ssl-certificate} (default: @code{#f}) Where to find the certificate for secure connections. Set it to @code{#f} if you don't have a certificate or you don't want to use HTTPS. @item @code{ssl-certificate-key} (default: @code{#f}) Where to find the private key for secure connections. Set it to @code{#f} if you don't have a key or you don't want to use HTTPS. @item @code{server-tokens?} (default: @code{#f}) Whether the server should add its configuration to response. @item @code{raw-content} (default: @code{'()}) A list of raw lines added to the server block. @end table @end deftp @deftp {Data Type} nginx-upstream-configuration Data type representing the configuration of an nginx @code{upstream} block. This type has the following parameters: @table @asis @item @code{name} Name for this group of servers. @item @code{servers} Specify the addresses of the servers in the group. The address can be specified as a IP address (e.g.@: @samp{127.0.0.1}), domain name (e.g.@: @samp{backend1.example.com}) or a path to a UNIX socket using the prefix @samp{unix:}. For addresses using an IP address or domain name, the default port is 80, and a different port can be specified explicitly. @end table @end deftp @deftp {Data Type} nginx-location-configuration Data type representing the configuration of an nginx @code{location} block. This type has the following parameters: @table @asis @item @code{uri} URI which this location block matches. @anchor{nginx-location-configuration body} @item @code{body} Body of the location block, specified as a list of strings. This can contain many configuration directives. For example, to pass requests to a upstream server group defined using an @code{nginx-upstream-configuration} block, the following directive would be specified in the body @samp{(list "proxy_pass http://upstream-name;")}. @end table @end deftp @deftp {Data Type} nginx-named-location-configuration Data type representing the configuration of an nginx named location block. Named location blocks are used for request redirection, and not used for regular request processing. This type has the following parameters: @table @asis @item @code{name} Name to identify this location block. @item @code{body} @xref{nginx-location-configuration body}, as the body for named location blocks can be used in a similar way to the @code{nginx-location-configuration body}. One restriction is that the body of a named location block cannot contain location blocks. @end table @end deftp @subsubheading Varnish Cache @cindex Varnish Varnish is a fast cache server that sits in between web applications and end users. It proxies requests from clients and caches the accessed URLs such that multiple requests for the same resource only creates one request to the back-end. @defvr {Scheme Variable} varnish-service-type Service type for the Varnish daemon. @end defvr @deftp {Data Type} varnish-configuration Data type representing the @code{varnish} service configuration. This type has the following parameters: @table @asis @item @code{package} (default: @code{varnish}) The Varnish package to use. @item @code{name} (default: @code{"default"}) A name for this Varnish instance. Varnish will create a directory in @file{/var/varnish/} with this name and keep temporary files there. If the name starts with a forward slash, it is interpreted as an absolute directory name. Pass the @code{-n} argument to other Varnish programs to connect to the named instance, e.g.@: @command{varnishncsa -n default}. @item @code{backend} (default: @code{"localhost:8080"}) The backend to use. This option has no effect if @code{vcl} is set. @item @code{vcl} (default: #f) The @dfn{VCL} (Varnish Configuration Language) program to run. If this is @code{#f}, Varnish will proxy @code{backend} using the default configuration. Otherwise this must be a file-like object with valid VCL syntax. @c Varnish does not support HTTPS, so keep this URL to avoid confusion. For example, to mirror @url{https://www.gnu.org,www.gnu.org} with VCL you can do something along these lines: @lisp (define %gnu-mirror (plain-file "gnu.vcl" "vcl 4.1; backend gnu @{ .host = \"www.gnu.org\"; @}")) (operating-system ;; @dots{} (services (cons (service varnish-service-type (varnish-configuration (listen '(":80")) (vcl %gnu-mirror))) %base-services))) @end lisp The configuration of an already running Varnish instance can be inspected and changed using the @command{varnishadm} program. Consult the @url{https://varnish-cache.org/docs/,Varnish User Guide} and @url{https://book.varnish-software.com/4.0/,Varnish Book} for comprehensive documentation on Varnish and its configuration language. @item @code{listen} (default: @code{'("localhost:80")}) List of addresses Varnish will listen on. @item @code{storage} (default: @code{'("malloc,128m")}) List of storage backends that will be available in VCL. @item @code{parameters} (default: @code{'()}) List of run-time parameters in the form @code{'(("parameter" . "value"))}. @item @code{extra-options} (default: @code{'()}) Additional arguments to pass to the @command{varnishd} process. @end table @end deftp @subsubheading Patchwork @cindex Patchwork Patchwork is a patch tracking system. It can collect patches sent to a mailing list, and display them in a web interface. @defvr {Scheme Variable} patchwork-service-type Service type for Patchwork. @end defvr The following example is an example of a minimal service for Patchwork, for the @code{patchwork.example.com} domain. @lisp (service patchwork-service-type (patchwork-configuration (domain "patchwork.example.com") (settings-module (patchwork-settings-module (allowed-hosts (list domain)) (default-from-email "patchwork@@patchwork.example.com"))) (getmail-retriever-config (getmail-retriever-configuration (type "SimpleIMAPSSLRetriever") (server "imap.example.com") (port 993) (username "patchwork") (password-command (list (file-append coreutils "/bin/cat") "/etc/getmail-patchwork-imap-password")) (extra-parameters '((mailboxes . ("Patches")))))))) @end lisp There are three records for configuring the Patchwork service. The @code{} relates to the configuration for Patchwork within the HTTPD service. The @code{settings-module} field within the @code{} record can be populated with the @code{} record, which describes a settings module that is generated within the Guix store. For the @code{database-configuration} field within the @code{}, the @code{} must be used. @deftp {Data Type} patchwork-configuration Data type representing the Patchwork service configuration. This type has the following parameters: @table @asis @item @code{patchwork} (default: @code{patchwork}) The Patchwork package to use. @item @code{domain} The domain to use for Patchwork, this is used in the HTTPD service virtual host. @item @code{settings-module} The settings module to use for Patchwork. As a Django application, Patchwork is configured with a Python module containing the settings. This can either be an instance of the @code{} record, any other record that represents the settings in the store, or a directory outside of the store. @item @code{static-path} (default: @code{"/static/"}) The path under which the HTTPD service should serve the static files. @item @code{getmail-retriever-config} The getmail-retriever-configuration record value to use with Patchwork. Getmail will be configured with this value, the messages will be delivered to Patchwork. @end table @end deftp @deftp {Data Type} patchwork-settings-module Data type representing a settings module for Patchwork. Some of these settings relate directly to Patchwork, but others relate to Django, the web framework used by Patchwork, or the Django Rest Framework library. This type has the following parameters: @table @asis @item @code{database-configuration} (default: @code{(patchwork-database-configuration)}) The database connection settings used for Patchwork. See the @code{} record type for more information. @item @code{secret-key-file} (default: @code{"/etc/patchwork/django-secret-key"}) Patchwork, as a Django web application uses a secret key for cryptographically signing values. This file should contain a unique unpredictable value. If this file does not exist, it will be created and populated with a random value by the patchwork-setup shepherd service. This setting relates to Django. @item @code{allowed-hosts} A list of valid hosts for this Patchwork service. This should at least include the domain specified in the @code{} record. This is a Django setting. @item @code{default-from-email} The email address from which Patchwork should send email by default. This is a Patchwork setting. @item @code{static-url} (default: @code{#f}) The URL to use when serving static assets. It can be part of a URL, or a full URL, but must end in a @code{/}. If the default value is used, the @code{static-path} value from the @code{} record will be used. This is a Django setting. @item @code{admins} (default: @code{'()}) Email addresses to send the details of errors that occur. Each value should be a list containing two elements, the name and then the email address. This is a Django setting. @item @code{debug?} (default: @code{#f}) Whether to run Patchwork in debug mode. If set to @code{#t}, detailed error messages will be shown. This is a Django setting. @item @code{enable-rest-api?} (default: @code{#t}) Whether to enable the Patchwork REST API. This is a Patchwork setting. @item @code{enable-xmlrpc?} (default: @code{#t}) Whether to enable the XML RPC API. This is a Patchwork setting. @item @code{force-https-links?} (default: @code{#t}) Whether to use HTTPS links on Patchwork pages. This is a Patchwork setting. @item @code{extra-settings} (default: @code{""}) Extra code to place at the end of the Patchwork settings module. @end table @end deftp @deftp {Data Type} patchwork-database-configuration Data type representing the database configuration for Patchwork. @table @asis @item @code{engine} (default: @code{"django.db.backends.postgresql_psycopg2"}) The database engine to use. @item @code{name} (default: @code{"patchwork"}) The name of the database to use. @item @code{user} (default: @code{"httpd"}) The user to connect to the database as. @item @code{password} (default: @code{""}) The password to use when connecting to the database. @item @code{host} (default: @code{""}) The host to make the database connection to. @item @code{port} (default: @code{""}) The port on which to connect to the database. @end table @end deftp @subsubheading Mumi @cindex Mumi, Debbugs Web interface @cindex Debbugs, Mumi Web interface @uref{https://git.elephly.net/gitweb.cgi?p=software/mumi.git, Mumi} is a Web interface to the Debbugs bug tracker, by default for @uref{https://bugs.gnu.org, the GNU instance}. Mumi is a Web server, but it also fetches and indexes mail retrieved from Debbugs. @defvr {Scheme Variable} mumi-service-type This is the service type for Mumi. @end defvr @deftp {Data Type} mumi-configuration Data type representing the Mumi service configuration. This type has the following fields: @table @asis @item @code{mumi} (default: @code{mumi}) The Mumi package to use. @item @code{mailer?} (default: @code{#true}) Whether to enable or disable the mailer component. @item @code{mumi-configuration-sender} The email address used as the sender for comments. @item @code{mumi-configuration-smtp} A URI to configure the SMTP settings for Mailutils. This could be something like @code{sendmail:///path/to/bin/msmtp} or any other URI supported by Mailutils. @xref{SMTP Mailboxes, SMTP Mailboxes,, mailutils, GNU@tie{}Mailutils}. @end table @end deftp @subsubheading FastCGI @cindex fastcgi @cindex fcgiwrap FastCGI is an interface between the front-end and the back-end of a web service. It is a somewhat legacy facility; new web services should generally just talk HTTP between the front-end and the back-end. However there are a number of back-end services such as PHP or the optimized HTTP Git repository access that use FastCGI, so we have support for it in Guix. To use FastCGI, you configure the front-end web server (e.g., nginx) to dispatch some subset of its requests to the fastcgi backend, which listens on a local TCP or UNIX socket. There is an intermediary @code{fcgiwrap} program that sits between the actual backend process and the web server. The front-end indicates which backend program to run, passing that information to the @code{fcgiwrap} process. @defvr {Scheme Variable} fcgiwrap-service-type A service type for the @code{fcgiwrap} FastCGI proxy. @end defvr @deftp {Data Type} fcgiwrap-configuration Data type representing the configuration of the @code{fcgiwrap} service. This type has the following parameters: @table @asis @item @code{package} (default: @code{fcgiwrap}) The fcgiwrap package to use. @item @code{socket} (default: @code{tcp:127.0.0.1:9000}) The socket on which the @code{fcgiwrap} process should listen, as a string. Valid @var{socket} values include @code{unix:@var{/path/to/unix/socket}}, @code{tcp:@var{dot.ted.qu.ad}:@var{port}} and @code{tcp6:[@var{ipv6_addr}]:port}. @item @code{user} (default: @code{fcgiwrap}) @itemx @code{group} (default: @code{fcgiwrap}) The user and group names, as strings, under which to run the @code{fcgiwrap} process. The @code{fastcgi} service will ensure that if the user asks for the specific user or group names @code{fcgiwrap} that the corresponding user and/or group is present on the system. It is possible to configure a FastCGI-backed web service to pass HTTP authentication information from the front-end to the back-end, and to allow @code{fcgiwrap} to run the back-end process as a corresponding local user. To enable this capability on the back-end, run @code{fcgiwrap} as the @code{root} user and group. Note that this capability also has to be configured on the front-end as well. @end table @end deftp @cindex php-fpm PHP-FPM (FastCGI Process Manager) is an alternative PHP FastCGI implementation with some additional features useful for sites of any size. These features include: @itemize @bullet @item Adaptive process spawning @item Basic statistics (similar to Apache's mod_status) @item Advanced process management with graceful stop/start @item Ability to start workers with different uid/gid/chroot/environment and different php.ini (replaces safe_mode) @item Stdout & stderr logging @item Emergency restart in case of accidental opcode cache destruction @item Accelerated upload support @item Support for a "slowlog" @item Enhancements to FastCGI, such as fastcgi_finish_request() - a special function to finish request & flush all data while continuing to do something time-consuming (video converting, stats processing, etc.) @end itemize ...@: and much more. @defvr {Scheme Variable} php-fpm-service-type A Service type for @code{php-fpm}. @end defvr @deftp {Data Type} php-fpm-configuration Data Type for php-fpm service configuration. @table @asis @item @code{php} (default: @code{php}) The php package to use. @item @code{socket} (default: @code{(string-append "/var/run/php" (version-major (package-version php)) "-fpm.sock")}) The address on which to accept FastCGI requests. Valid syntaxes are: @table @asis @item @code{"ip.add.re.ss:port"} Listen on a TCP socket to a specific address on a specific port. @item @code{"port"} Listen on a TCP socket to all addresses on a specific port. @item @code{"/path/to/unix/socket"} Listen on a unix socket. @end table @item @code{user} (default: @code{php-fpm}) User who will own the php worker processes. @item @code{group} (default: @code{php-fpm}) Group of the worker processes. @item @code{socket-user} (default: @code{php-fpm}) User who can speak to the php-fpm socket. @item @code{socket-group} (default: @code{nginx}) Group that can speak to the php-fpm socket. @item @code{pid-file} (default: @code{(string-append "/var/run/php" (version-major (package-version php)) "-fpm.pid")}) The process id of the php-fpm process is written to this file once the service has started. @item @code{log-file} (default: @code{(string-append "/var/log/php" (version-major (package-version php)) "-fpm.log")}) Log for the php-fpm master process. @item @code{process-manager} (default: @code{(php-fpm-dynamic-process-manager-configuration)}) Detailed settings for the php-fpm process manager. Must be one of: @table @asis @item @code{} @item @code{} @item @code{} @end table @item @code{display-errors} (default @code{#f}) Determines whether php errors and warning should be sent to clients and displayed in their browsers. This is useful for local php development, but a security risk for public sites, as error messages can reveal passwords and personal data. @item @code{timezone} (default @code{#f}) Specifies @code{php_admin_value[date.timezone]} parameter. @item @code{workers-logfile} (default @code{(string-append "/var/log/php" (version-major (package-version php)) "-fpm.www.log")}) This file will log the @code{stderr} outputs of php worker processes. Can be set to @code{#f} to disable logging. @item @code{file} (default @code{#f}) An optional override of the whole configuration. You can use the @code{mixed-text-file} function or an absolute filepath for it. @item @code{php-ini-file} (default @code{#f}) An optional override of the default php settings. It may be any ``file-like'' object (@pxref{G-Expressions, file-like objects}). You can use the @code{mixed-text-file} function or an absolute filepath for it. For local development it is useful to set a higher timeout and memory limit for spawned php processes. This be accomplished with the following operating system configuration snippet: @lisp (define %local-php-ini (plain-file "php.ini" "memory_limit = 2G max_execution_time = 1800")) (operating-system ;; @dots{} (services (cons (service php-fpm-service-type (php-fpm-configuration (php-ini-file %local-php-ini))) %base-services))) @end lisp Consult the @url{https://www.php.net/manual/en/ini.core.php,core php.ini directives} for comprehensive documentation on the acceptable @file{php.ini} directives. @end table @end deftp @deftp {Data type} php-fpm-dynamic-process-manager-configuration Data Type for the @code{dynamic} php-fpm process manager. With the @code{dynamic} process manager, spare worker processes are kept around based on it's configured limits. @table @asis @item @code{max-children} (default: @code{5}) Maximum of worker processes. @item @code{start-servers} (default: @code{2}) How many worker processes should be started on start-up. @item @code{min-spare-servers} (default: @code{1}) How many spare worker processes should be kept around at minimum. @item @code{max-spare-servers} (default: @code{3}) How many spare worker processes should be kept around at maximum. @end table @end deftp @deftp {Data type} php-fpm-static-process-manager-configuration Data Type for the @code{static} php-fpm process manager. With the @code{static} process manager, an unchanging number of worker processes are created. @table @asis @item @code{max-children} (default: @code{5}) Maximum of worker processes. @end table @end deftp @deftp {Data type} php-fpm-on-demand-process-manager-configuration Data Type for the @code{on-demand} php-fpm process manager. With the @code{on-demand} process manager, worker processes are only created as requests arrive. @table @asis @item @code{max-children} (default: @code{5}) Maximum of worker processes. @item @code{process-idle-timeout} (default: @code{10}) The time in seconds after which a process with no requests is killed. @end table @end deftp @deffn {Scheme Procedure} nginx-php-location @ [#:nginx-package nginx] @ [socket (string-append "/var/run/php" @ (version-major (package-version php)) @ "-fpm.sock")] A helper function to quickly add php to an @code{nginx-server-configuration}. @end deffn A simple services setup for nginx with php can look like this: @lisp (services (cons* (service dhcp-client-service-type) (service php-fpm-service-type) (service nginx-service-type (nginx-server-configuration (server-name '("example.com")) (root "/srv/http/") (locations (list (nginx-php-location))) (listen '("80")) (ssl-certificate #f) (ssl-certificate-key #f))) %base-services)) @end lisp @cindex cat-avatar-generator The cat avatar generator is a simple service to demonstrate the use of php-fpm in @code{Nginx}. It is used to generate cat avatar from a seed, for instance the hash of a user's email address. @deffn {Scheme Procedure} cat-avatar-generator-service @ [#:cache-dir "/var/cache/cat-avatar-generator"] @ [#:package cat-avatar-generator] @ [#:configuration (nginx-server-configuration)] Returns an nginx-server-configuration that inherits @code{configuration}. It extends the nginx configuration to add a server block that serves @code{package}, a version of cat-avatar-generator. During execution, cat-avatar-generator will be able to use @code{cache-dir} as its cache directory. @end deffn A simple setup for cat-avatar-generator can look like this: @lisp (services (cons* (cat-avatar-generator-service #:configuration (nginx-server-configuration (server-name '("example.com")))) ... %base-services)) @end lisp @subsubheading Hpcguix-web @cindex hpcguix-web The @uref{https://github.com/UMCUGenetics/hpcguix-web/, hpcguix-web} program is a customizable web interface to browse Guix packages, initially designed for users of high-performance computing (HPC) clusters. @defvr {Scheme Variable} hpcguix-web-service-type The service type for @code{hpcguix-web}. @end defvr @deftp {Data Type} hpcguix-web-configuration Data type for the hpcguix-web service configuration. @table @asis @item @code{specs} A gexp (@pxref{G-Expressions}) specifying the hpcguix-web service configuration. The main items available in this spec are: @table @asis @item @code{title-prefix} (default: @code{"hpcguix | "}) The page title prefix. @item @code{guix-command} (default: @code{"guix"}) The @command{guix} command. @item @code{package-filter-proc} (default: @code{(const #t)}) A procedure specifying how to filter packages that are displayed. @item @code{package-page-extension-proc} (default: @code{(const '())}) Extension package for @code{hpcguix-web}. @item @code{menu} (default: @code{'()}) Additional entry in page @code{menu}. @item @code{channels} (default: @code{%default-channels}) List of channels from which the package list is built (@pxref{Channels}). @item @code{package-list-expiration} (default: @code{(* 12 3600)}) The expiration time, in seconds, after which the package list is rebuilt from the latest instances of the given channels. @end table See the hpcguix-web repository for a @uref{https://github.com/UMCUGenetics/hpcguix-web/blob/master/hpcweb-configuration.scm, complete example}. @item @code{package} (default: @code{hpcguix-web}) The hpcguix-web package to use. @end table @end deftp A typical hpcguix-web service declaration looks like this: @lisp (service hpcguix-web-service-type (hpcguix-web-configuration (specs #~(define site-config (hpcweb-configuration (title-prefix "Guix-HPC - ") (menu '(("/about" "ABOUT")))))))) @end lisp @quotation Note The hpcguix-web service periodically updates the package list it publishes by pulling channels from Git. To that end, it needs to access X.509 certificates so that it can authenticate Git servers when communicating over HTTPS, and it assumes that @file{/etc/ssl/certs} contains those certificates. Thus, make sure to add @code{nss-certs} or another certificate package to the @code{packages} field of your configuration. @ref{X.509 Certificates}, for more information on X.509 certificates. @end quotation @subsubheading gmnisrv @cindex gmnisrv The @uref{https://git.sr.ht/~sircmpwn/gmnisrv, gmnisrv} program is a simple @uref{https://gemini.circumlunar.space/, Gemini} protocol server. @deffn {Scheme Variable} gmnisrv-service-type This is the type of the gmnisrv service, whose value should be a @code{gmnisrv-configuration} object, as in this example: @lisp (service gmnisrv-service-type (gmnisrv-configuration (config-file (local-file "./my-gmnisrv.ini")))) @end lisp @end deffn @deftp {Data Type} gmnisrv-configuration Data type representing the configuration of gmnisrv. @table @asis @item @code{package} (default: @var{gmnisrv}) Package object of the gmnisrv server. @item @code{config-file} (default: @code{%default-gmnisrv-config-file}) File-like object of the gmnisrv configuration file to use. The default configuration listens on port 1965 and serves files from @file{/srv/gemini}. Certificates are stored in @file{/var/lib/gemini/certs}. For more information, run @command{man gmnisrv} and @command{man gmnisrv.ini}. @end table @end deftp @node Certificate Services @subsection Certificate Services @cindex Web @cindex HTTP, HTTPS @cindex Let's Encrypt @cindex TLS certificates The @code{(gnu services certbot)} module provides a service to automatically obtain a valid TLS certificate from the Let's Encrypt certificate authority. These certificates can then be used to serve content securely over HTTPS or other TLS-based protocols, with the knowledge that the client will be able to verify the server's authenticity. @url{https://letsencrypt.org/, Let's Encrypt} provides the @code{certbot} tool to automate the certification process. This tool first securely generates a key on the server. It then makes a request to the Let's Encrypt certificate authority (CA) to sign the key. The CA checks that the request originates from the host in question by using a challenge-response protocol, requiring the server to provide its response over HTTP. If that protocol completes successfully, the CA signs the key, resulting in a certificate. That certificate is valid for a limited period of time, and therefore to continue to provide TLS services, the server needs to periodically ask the CA to renew its signature. The certbot service automates this process: the initial key generation, the initial certification request to the Let's Encrypt service, the web server challenge/response integration, writing the certificate to disk, the automated periodic renewals, and the deployment tasks associated with the renewal (e.g.@: reloading services, copying keys with different permissions). Certbot is run twice a day, at a random minute within the hour. It won't do anything until your certificates are due for renewal or revoked, but running it regularly would give your service a chance of staying online in case a Let's Encrypt-initiated revocation happened for some reason. By using this service, you agree to the ACME Subscriber Agreement, which can be found there: @url{https://acme-v01.api.letsencrypt.org/directory}. @defvr {Scheme Variable} certbot-service-type A service type for the @code{certbot} Let's Encrypt client. Its value must be a @code{certbot-configuration} record as in this example: @lisp (define %nginx-deploy-hook (program-file "nginx-deploy-hook" #~(let ((pid (call-with-input-file "/var/run/nginx/pid" read))) (kill pid SIGHUP)))) (service certbot-service-type (certbot-configuration (email "foo@@example.net") (certificates (list (certificate-configuration (domains '("example.net" "www.example.net")) (deploy-hook %nginx-deploy-hook)) (certificate-configuration (domains '("bar.example.net"))))))) @end lisp See below for details about @code{certbot-configuration}. @end defvr @deftp {Data Type} certbot-configuration Data type representing the configuration of the @code{certbot} service. This type has the following parameters: @table @asis @item @code{package} (default: @code{certbot}) The certbot package to use. @item @code{webroot} (default: @code{/var/www}) The directory from which to serve the Let's Encrypt challenge/response files. @item @code{certificates} (default: @code{()}) A list of @code{certificates-configuration}s for which to generate certificates and request signatures. Each certificate has a @code{name} and several @code{domains}. @item @code{email} (default: @code{#f}) Optional email address used for registration and recovery contact. Setting this is encouraged as it allows you to receive important notifications about the account and issued certificates. @item @code{server} (default: @code{#f}) Optional URL of ACME server. Setting this overrides certbot's default, which is the Let's Encrypt server. @item @code{rsa-key-size} (default: @code{2048}) Size of the RSA key. @item @code{default-location} (default: @i{see below}) The default @code{nginx-location-configuration}. Because @code{certbot} needs to be able to serve challenges and responses, it needs to be able to run a web server. It does so by extending the @code{nginx} web service with an @code{nginx-server-configuration} listening on the @var{domains} on port 80, and which has a @code{nginx-location-configuration} for the @code{/.well-known/} URI path subspace used by Let's Encrypt. @xref{Web Services}, for more on these nginx configuration data types. Requests to other URL paths will be matched by the @code{default-location}, which if present is added to all @code{nginx-server-configuration}s. By default, the @code{default-location} will issue a redirect from @code{http://@var{domain}/...} to @code{https://@var{domain}/...}, leaving you to define what to serve on your site via @code{https}. Pass @code{#f} to not issue a default location. @end table @end deftp @deftp {Data Type} certificate-configuration Data type representing the configuration of a certificate. This type has the following parameters: @table @asis @item @code{name} (default: @i{see below}) This name is used by Certbot for housekeeping and in file paths; it doesn't affect the content of the certificate itself. To see certificate names, run @code{certbot certificates}. Its default is the first provided domain. @item @code{domains} (default: @code{()}) The first domain provided will be the subject CN of the certificate, and all domains will be Subject Alternative Names on the certificate. @item @code{challenge} (default: @code{#f}) The challenge type that has to be run by certbot. If @code{#f} is specified, default to the HTTP challenge. If a value is specified, defaults to the manual plugin (see @code{authentication-hook}, @code{cleanup-hook} and the documentation at @url{https://certbot.eff.org/docs/using.html#hooks}), and gives Let's Encrypt permission to log the public IP address of the requesting machine. @item @code{authentication-hook} (default: @code{#f}) Command to be run in a shell once for each certificate challenge to be answered. For this command, the shell variable @code{$CERTBOT_DOMAIN} will contain the domain being authenticated, @code{$CERTBOT_VALIDATION} contains the validation string and @code{$CERTBOT_TOKEN} contains the file name of the resource requested when performing an HTTP-01 challenge. @item @code{cleanup-hook} (default: @code{#f}) Command to be run in a shell once for each certificate challenge that have been answered by the @code{auth-hook}. For this command, the shell variables available in the @code{auth-hook} script are still available, and additionally @code{$CERTBOT_AUTH_OUTPUT} will contain the standard output of the @code{auth-hook} script. @item @code{deploy-hook} (default: @code{#f}) Command to be run in a shell once for each successfully issued certificate. For this command, the shell variable @code{$RENEWED_LINEAGE} will point to the config live subdirectory (for example, @samp{"/etc/letsencrypt/live/example.com"}) containing the new certificates and keys; the shell variable @code{$RENEWED_DOMAINS} will contain a space-delimited list of renewed certificate domains (for example, @samp{"example.com www.example.com"}. @end table @end deftp For each @code{certificate-configuration}, the certificate is saved to @code{/etc/letsencrypt/live/@var{name}/fullchain.pem} and the key is saved to @code{/etc/letsencrypt/live/@var{name}/privkey.pem}. @node DNS Services @subsection DNS Services @cindex DNS (domain name system) @cindex domain name system (DNS) The @code{(gnu services dns)} module provides services related to the @dfn{domain name system} (DNS). It provides a server service for hosting an @emph{authoritative} DNS server for multiple zones, slave or master. This service uses @uref{https://www.knot-dns.cz/, Knot DNS}. And also a caching and forwarding DNS server for the LAN, which uses @uref{http://www.thekelleys.org.uk/dnsmasq/doc.html, dnsmasq}. @subsubheading Knot Service An example configuration of an authoritative server for two zones, one master and one slave, is: @lisp (define-zone-entries example.org.zone ;; Name TTL Class Type Data ("@@" "" "IN" "A" "127.0.0.1") ("@@" "" "IN" "NS" "ns") ("ns" "" "IN" "A" "127.0.0.1")) (define master-zone (knot-zone-configuration (domain "example.org") (zone (zone-file (origin "example.org") (entries example.org.zone))))) (define slave-zone (knot-zone-configuration (domain "plop.org") (dnssec-policy "default") (master (list "plop-master")))) (define plop-master (knot-remote-configuration (id "plop-master") (address (list "208.76.58.171")))) (operating-system ;; ... (services (cons* (service knot-service-type (knot-configuration (remotes (list plop-master)) (zones (list master-zone slave-zone)))) ;; ... %base-services))) @end lisp @deffn {Scheme Variable} knot-service-type This is the type for the Knot DNS server. Knot DNS is an authoritative DNS server, meaning that it can serve multiple zones, that is to say domain names you would buy from a registrar. This server is not a resolver, meaning that it can only resolve names for which it is authoritative. This server can be configured to serve zones as a master server or a slave server as a per-zone basis. Slave zones will get their data from masters, and will serve it as an authoritative server. From the point of view of a resolver, there is no difference between master and slave. The following data types are used to configure the Knot DNS server: @end deffn @deftp {Data Type} knot-key-configuration Data type representing a key. This type has the following parameters: @table @asis @item @code{id} (default: @code{""}) An identifier for other configuration fields to refer to this key. IDs must be unique and must not be empty. @item @code{algorithm} (default: @code{#f}) The algorithm to use. Choose between @code{#f}, @code{'hmac-md5}, @code{'hmac-sha1}, @code{'hmac-sha224}, @code{'hmac-sha256}, @code{'hmac-sha384} and @code{'hmac-sha512}. @item @code{secret} (default: @code{""}) The secret key itself. @end table @end deftp @deftp {Data Type} knot-acl-configuration Data type representing an Access Control List (ACL) configuration. This type has the following parameters: @table @asis @item @code{id} (default: @code{""}) An identifier for other configuration fields to refer to this key. IDs must be unique and must not be empty. @item @code{address} (default: @code{'()}) An ordered list of IP addresses, network subnets, or network ranges represented with strings. The query must match one of them. Empty value means that address match is not required. @item @code{key} (default: @code{'()}) An ordered list of references to keys represented with strings. The string must match a key ID defined in a @code{knot-key-configuration}. No key means that a key is not require to match that ACL. @item @code{action} (default: @code{'()}) An ordered list of actions that are permitted or forbidden by this ACL. Possible values are lists of zero or more elements from @code{'transfer}, @code{'notify} and @code{'update}. @item @code{deny?} (default: @code{#f}) When true, the ACL defines restrictions. Listed actions are forbidden. When false, listed actions are allowed. @end table @end deftp @deftp {Data Type} zone-entry Data type representing a record entry in a zone file. This type has the following parameters: @table @asis @item @code{name} (default: @code{"@@"}) The name of the record. @code{"@@"} refers to the origin of the zone. Names are relative to the origin of the zone. For example, in the @code{example.org} zone, @code{"ns.example.org"} actually refers to @code{ns.example.org.example.org}. Names ending with a dot are absolute, which means that @code{"ns.example.org."} refers to @code{ns.example.org}. @item @code{ttl} (default: @code{""}) The Time-To-Live (TTL) of this record. If not set, the default TTL is used. @item @code{class} (default: @code{"IN"}) The class of the record. Knot currently supports only @code{"IN"} and partially @code{"CH"}. @item @code{type} (default: @code{"A"}) The type of the record. Common types include A (IPv4 address), AAAA (IPv6 address), NS (Name Server) and MX (Mail eXchange). Many other types are defined. @item @code{data} (default: @code{""}) The data contained in the record. For instance an IP address associated with an A record, or a domain name associated with an NS record. Remember that domain names are relative to the origin unless they end with a dot. @end table @end deftp @deftp {Data Type} zone-file Data type representing the content of a zone file. This type has the following parameters: @table @asis @item @code{entries} (default: @code{'()}) The list of entries. The SOA record is taken care of, so you don't need to put it in the list of entries. This list should probably contain an entry for your primary authoritative DNS server. Other than using a list of entries directly, you can use @code{define-zone-entries} to define a object containing the list of entries more easily, that you can later pass to the @code{entries} field of the @code{zone-file}. @item @code{origin} (default: @code{""}) The name of your zone. This parameter cannot be empty. @item @code{ns} (default: @code{"ns"}) The domain of your primary authoritative DNS server. The name is relative to the origin, unless it ends with a dot. It is mandatory that this primary DNS server corresponds to an NS record in the zone and that it is associated to an IP address in the list of entries. @item @code{mail} (default: @code{"hostmaster"}) An email address people can contact you at, as the owner of the zone. This is translated as @code{@@}. @item @code{serial} (default: @code{1}) The serial number of the zone. As this is used to keep track of changes by both slaves and resolvers, it is mandatory that it @emph{never} decreases. Always increment it when you make a change in your zone. @item @code{refresh} (default: @code{(* 2 24 3600)}) The frequency at which slaves will do a zone transfer. This value is a number of seconds. It can be computed by multiplications or with @code{(string->duration)}. @item @code{retry} (default: @code{(* 15 60)}) The period after which a slave will retry to contact its master when it fails to do so a first time. @item @code{expiry} (default: @code{(* 14 24 3600)}) Default TTL of records. Existing records are considered correct for at most this amount of time. After this period, resolvers will invalidate their cache and check again that it still exists. @item @code{nx} (default: @code{3600}) Default TTL of inexistant records. This delay is usually short because you want your new domains to reach everyone quickly. @end table @end deftp @deftp {Data Type} knot-remote-configuration Data type representing a remote configuration. This type has the following parameters: @table @asis @item @code{id} (default: @code{""}) An identifier for other configuration fields to refer to this remote. IDs must be unique and must not be empty. @item @code{address} (default: @code{'()}) An ordered list of destination IP addresses. Addresses are tried in sequence. An optional port can be given with the @@ separator. For instance: @code{(list "1.2.3.4" "2.3.4.5@@53")}. Default port is 53. @item @code{via} (default: @code{'()}) An ordered list of source IP addresses. An empty list will have Knot choose an appropriate source IP. An optional port can be given with the @@ separator. The default is to choose at random. @item @code{key} (default: @code{#f}) A reference to a key, that is a string containing the identifier of a key defined in a @code{knot-key-configuration} field. @end table @end deftp @deftp {Data Type} knot-keystore-configuration Data type representing a keystore to hold dnssec keys. This type has the following parameters: @table @asis @item @code{id} (default: @code{""}) The id of the keystore. It must not be empty. @item @code{backend} (default: @code{'pem}) The backend to store the keys in. Can be @code{'pem} or @code{'pkcs11}. @item @code{config} (default: @code{"/var/lib/knot/keys/keys"}) The configuration string of the backend. An example for the PKCS#11 is: @code{"pkcs11:token=knot;pin-value=1234 /gnu/store/.../lib/pkcs11/libsofthsm2.so"}. For the pem backend, the string represents a path in the file system. @end table @end deftp @deftp {Data Type} knot-policy-configuration Data type representing a dnssec policy. Knot DNS is able to automatically sign your zones. It can either generate and manage your keys automatically or use keys that you generate. Dnssec is usually implemented using two keys: a Key Signing Key (KSK) that is used to sign the second, and a Zone Signing Key (ZSK) that is used to sign the zone. In order to be trusted, the KSK needs to be present in the parent zone (usually a top-level domain). If your registrar supports dnssec, you will have to send them your KSK's hash so they can add a DS record in their zone. This is not automated and need to be done each time you change your KSK. The policy also defines the lifetime of keys. Usually, ZSK can be changed easily and use weaker cryptographic functions (they use lower parameters) in order to sign records quickly, so they are changed often. The KSK however requires manual interaction with the registrar, so they are changed less often and use stronger parameters because they sign only one record. This type has the following parameters: @table @asis @item @code{id} (default: @code{""}) The id of the policy. It must not be empty. @item @code{keystore} (default: @code{"default"}) A reference to a keystore, that is a string containing the identifier of a keystore defined in a @code{knot-keystore-configuration} field. The @code{"default"} identifier means the default keystore (a kasp database that was setup by this service). @item @code{manual?} (default: @code{#f}) Whether the key management is manual or automatic. @item @code{single-type-signing?} (default: @code{#f}) When @code{#t}, use the Single-Type Signing Scheme. @item @code{algorithm} (default: @code{"ecdsap256sha256"}) An algorithm of signing keys and issued signatures. @item @code{ksk-size} (default: @code{256}) The length of the KSK. Note that this value is correct for the default algorithm, but would be unsecure for other algorithms. @item @code{zsk-size} (default: @code{256}) The length of the ZSK. Note that this value is correct for the default algorithm, but would be unsecure for other algorithms. @item @code{dnskey-ttl} (default: @code{'default}) The TTL value for DNSKEY records added into zone apex. The special @code{'default} value means same as the zone SOA TTL. @item @code{zsk-lifetime} (default: @code{(* 30 24 3600)}) The period between ZSK publication and the next rollover initiation. @item @code{propagation-delay} (default: @code{(* 24 3600)}) An extra delay added for each key rollover step. This value should be high enough to cover propagation of data from the master server to all slaves. @item @code{rrsig-lifetime} (default: @code{(* 14 24 3600)}) A validity period of newly issued signatures. @item @code{rrsig-refresh} (default: @code{(* 7 24 3600)}) A period how long before a signature expiration the signature will be refreshed. @item @code{nsec3?} (default: @code{#f}) When @code{#t}, NSEC3 will be used instead of NSEC. @item @code{nsec3-iterations} (default: @code{5}) The number of additional times the hashing is performed. @item @code{nsec3-salt-length} (default: @code{8}) The length of a salt field in octets, which is appended to the original owner name before hashing. @item @code{nsec3-salt-lifetime} (default: @code{(* 30 24 3600)}) The validity period of newly issued salt field. @end table @end deftp @deftp {Data Type} knot-zone-configuration Data type representing a zone served by Knot. This type has the following parameters: @table @asis @item @code{domain} (default: @code{""}) The domain served by this configuration. It must not be empty. @item @code{file} (default: @code{""}) The file where this zone is saved. This parameter is ignored by master zones. Empty means default location that depends on the domain name. @item @code{zone} (default: @code{(zone-file)}) The content of the zone file. This parameter is ignored by slave zones. It must contain a zone-file record. @item @code{master} (default: @code{'()}) A list of master remotes. When empty, this zone is a master. When set, this zone is a slave. This is a list of remotes identifiers. @item @code{ddns-master} (default: @code{#f}) The main master. When empty, it defaults to the first master in the list of masters. @item @code{notify} (default: @code{'()}) A list of slave remote identifiers. @item @code{acl} (default: @code{'()}) A list of acl identifiers. @item @code{semantic-checks?} (default: @code{#f}) When set, this adds more semantic checks to the zone. @item @code{disable-any?} (default: @code{#f}) When set, this forbids queries of the ANY type. @item @code{zonefile-sync} (default: @code{0}) The delay between a modification in memory and on disk. 0 means immediate synchronization. @item @code{zonefile-load} (default: @code{#f}) The way the zone file contents are applied during zone load. Possible values are: @itemize @item @code{#f} for using the default value from Knot, @item @code{'none} for not using the zone file at all, @item @code{'difference} for computing the difference between already available contents and zone contents and applying it to the current zone contents, @item @code{'difference-no-serial} for the same as @code{'difference}, but ignoring the SOA serial in the zone file, while the server takes care of it automatically. @item @code{'whole} for loading zone contents from the zone file. @end itemize @item @code{journal-content} (default: @code{#f}) The way the journal is used to store zone and its changes. Possible values are @code{'none} to not use it at all, @code{'changes} to store changes and @code{'all} to store contents. @code{#f} does not set this option, so the default value from Knot is used. @item @code{max-journal-usage} (default: @code{#f}) The maximum size for the journal on disk. @code{#f} does not set this option, so the default value from Knot is used. @item @code{max-journal-depth} (default: @code{#f}) The maximum size of the history. @code{#f} does not set this option, so the default value from Knot is used. @item @code{max-zone-size} (default: @code{#f}) The maximum size of the zone file. This limit is enforced for incoming transfer and updates. @code{#f} does not set this option, so the default value from Knot is used. @item @code{dnssec-policy} (default: @code{#f}) A reference to a @code{knot-policy-configuration} record, or the special name @code{"default"}. If the value is @code{#f}, there is no dnssec signing on this zone. @item @code{serial-policy} (default: @code{'increment}) A policy between @code{'increment} and @code{'unixtime}. @end table @end deftp @deftp {Data Type} knot-configuration Data type representing the Knot configuration. This type has the following parameters: @table @asis @item @code{knot} (default: @code{knot}) The Knot package. @item @code{run-directory} (default: @code{"/var/run/knot"}) The run directory. This directory will be used for pid file and sockets. @item @code{includes} (default: @code{'()}) A list of strings or file-like objects denoting other files that must be included at the top of the configuration file. @cindex secrets, Knot service This can be used to manage secrets out-of-band. For example, secret keys may be stored in an out-of-band file not managed by Guix, and thus not visible in @file{/gnu/store}---e.g., you could store secret key configuration in @file{/etc/knot/secrets.conf} and add this file to the @code{includes} list. One can generate a secret tsig key (for nsupdate and zone transfers with the keymgr command from the knot package. Note that the package is not automatically installed by the service. The following example shows how to generate a new tsig key: @example keymgr -t mysecret > /etc/knot/secrets.conf chmod 600 /etc/knot/secrets.conf @end example Also note that the generated key will be named @var{mysecret}, so it is the name that needs to be used in the @var{key} field of the @code{knot-acl-configuration} record and in other places that need to refer to that key. It can also be used to add configuration not supported by this interface. @item @code{listen-v4} (default: @code{"0.0.0.0"}) An ip address on which to listen. @item @code{listen-v6} (default: @code{"::"}) An ip address on which to listen. @item @code{listen-port} (default: @code{53}) A port on which to listen. @item @code{keys} (default: @code{'()}) The list of knot-key-configuration used by this configuration. @item @code{acls} (default: @code{'()}) The list of knot-acl-configuration used by this configuration. @item @code{remotes} (default: @code{'()}) The list of knot-remote-configuration used by this configuration. @item @code{zones} (default: @code{'()}) The list of knot-zone-configuration used by this configuration. @end table @end deftp @subsubheading Knot Resolver Service @deffn {Scheme Variable} knot-resolver-service-type This is the type of the knot resolver service, whose value should be an @code{knot-resolver-configuration} object as in this example: @lisp (service knot-resolver-service-type (knot-resolver-configuration (kresd-config-file (plain-file "kresd.conf" " net.listen('192.168.0.1', 5353) user('knot-resolver', 'knot-resolver') modules = @{ 'hints > iterate', 'stats', 'predict' @} cache.size = 100 * MB ")))) @end lisp For more information, refer its @url{https://knot-resolver.readthedocs.org/en/stable/daemon.html#configuration, manual}. @end deffn @deftp {Data Type} knot-resolver-configuration Data type representing the configuration of knot-resolver. @table @asis @item @code{package} (default: @var{knot-resolver}) Package object of the knot DNS resolver. @item @code{kresd-config-file} (default: %kresd.conf) File-like object of the kresd configuration file to use, by default it will listen on @code{127.0.0.1} and @code{::1}. @item @code{garbage-collection-interval} (default: 1000) Number of milliseconds for @code{kres-cache-gc} to periodically trim the cache. @end table @end deftp @subsubheading Dnsmasq Service @deffn {Scheme Variable} dnsmasq-service-type This is the type of the dnsmasq service, whose value should be an @code{dnsmasq-configuration} object as in this example: @lisp (service dnsmasq-service-type (dnsmasq-configuration (no-resolv? #t) (servers '("192.168.1.1")))) @end lisp @end deffn @deftp {Data Type} dnsmasq-configuration Data type representing the configuration of dnsmasq. @table @asis @item @code{package} (default: @var{dnsmasq}) Package object of the dnsmasq server. @item @code{no-hosts?} (default: @code{#f}) When true, don't read the hostnames in /etc/hosts. @item @code{port} (default: @code{53}) The port to listen on. Setting this to zero completely disables DNS responses, leaving only DHCP and/or TFTP functions. @item @code{local-service?} (default: @code{#t}) Accept DNS queries only from hosts whose address is on a local subnet, ie a subnet for which an interface exists on the server. @item @code{listen-addresses} (default: @code{'()}) Listen on the given IP addresses. @item @code{resolv-file} (default: @code{"/etc/resolv.conf"}) The file to read the IP address of the upstream nameservers from. @item @code{no-resolv?} (default: @code{#f}) When true, don't read @var{resolv-file}. @item @code{servers} (default: @code{'()}) Specify IP address of upstream servers directly. @item @code{addresses} (default: @code{'()}) For each entry, specify an IP address to return for any host in the given domains. Queries in the domains are never forwarded and always replied to with the specified IP address. This is useful for redirecting hosts locally, for example: @lisp (service dnsmasq-service-type (dnsmasq-configuration (addresses '(; Redirect to a local web-server. "/example.org/127.0.0.1" ; Redirect subdomain to a specific IP. "/subdomain.example.org/192.168.1.42")))) @end lisp Note that rules in @file{/etc/hosts} take precedence over this. @item @code{cache-size} (default: @code{150}) Set the size of dnsmasq's cache. Setting the cache size to zero disables caching. @item @code{negative-cache?} (default: @code{#t}) When false, disable negative caching. @item @code{tftp-enable?} (default: @code{#f}) Whether to enable the built-in TFTP server. @item @code{tftp-no-fail?} (default: @code{#f}) If true, does not fail dnsmasq if the TFTP server could not start up. @item @code{tftp-single-port?} (default: @code{#f}) Whether to use only one single port for TFTP. @item @code{tftp-secure?} (default: @code{#f}) If true, only files owned by the user running the dnsmasq process are accessible. If dnsmasq is being run as root, different rules apply: @code{tftp-secure?} has no effect, but only files which have the world-readable bit set are accessible. @item @code{tftp-max} (default: @code{#f}) If set, sets the maximal number of concurrent connections allowed. @item @code{tftp-mtu} (default: @code{#f}) If set, sets the MTU for TFTP packets to that value. @item @code{tftp-no-blocksize?} (default: @code{#f}) If true, stops the TFTP server from negotiating the blocksize with a client. @item @code{tftp-lowercase?} (default: @code{#f}) Whether to convert all filenames in TFTP requests to lowercase. @item @code{tftp-port-range} (default: @code{#f}) If set, fixes the dynamical ports (one per client) to the given range (@code{","}). @item @code{tftp-root} (default: @code{/var/empty,lo}) Look for files to transfer using TFTP relative to the given directory. When this is set, TFTP paths which include @samp{..} are rejected, to stop clients getting outside the specified root. Absolute paths (starting with @samp{/}) are allowed, but they must be within the TFTP-root. If the optional interface argument is given, the directory is only used for TFTP requests via that interface. @item @code{tftp-unique-root} (default: @code{#f}) If set, add the IP or hardware address of the TFTP client as a path component on the end of the TFTP-root. Only valid if a TFTP root is set and the directory exists. Defaults to adding IP address (in standard dotted-quad format). For instance, if @option{--tftp-root} is @samp{/tftp} and client @samp{1.2.3.4} requests file @file{myfile} then the effective path will be @file{/tftp/1.2.3.4/myfile} if @file{/tftp/1.2.3.4} exists or @file{/tftp/myfile} otherwise. When @samp{=mac} is specified it will append the MAC address instead, using lowercase zero padded digits separated by dashes, e.g.: @samp{01-02-03-04-aa-bb}. Note that resolving MAC addresses is only possible if the client is in the local network or obtained a DHCP lease from dnsmasq. @end table @end deftp @subsubheading ddclient Service @cindex ddclient The ddclient service described below runs the ddclient daemon, which takes care of automatically updating DNS entries for service providers such as @uref{https://dyn.com/dns/, Dyn}. The following example show instantiates the service with its default configuration: @lisp (service ddclient-service-type) @end lisp Note that ddclient needs to access credentials that are stored in a @dfn{secret file}, by default @file{/etc/ddclient/secrets} (see @code{secret-file} below). You are expected to create this file manually, in an ``out-of-band'' fashion (you @emph{could} make this file part of the service configuration, for instance by using @code{plain-file}, but it will be world-readable @i{via} @file{/gnu/store}). See the examples in the @file{share/ddclient} directory of the @code{ddclient} package. @c %start of fragment Available @code{ddclient-configuration} fields are: @deftypevr {@code{ddclient-configuration} parameter} package ddclient The ddclient package. @end deftypevr @deftypevr {@code{ddclient-configuration} parameter} integer daemon The period after which ddclient will retry to check IP and domain name. Defaults to @samp{300}. @end deftypevr @deftypevr {@code{ddclient-configuration} parameter} boolean syslog Use syslog for the output. Defaults to @samp{#t}. @end deftypevr @deftypevr {@code{ddclient-configuration} parameter} string mail Mail to user. Defaults to @samp{"root"}. @end deftypevr @deftypevr {@code{ddclient-configuration} parameter} string mail-failure Mail failed update to user. Defaults to @samp{"root"}. @end deftypevr @deftypevr {@code{ddclient-configuration} parameter} string pid The ddclient PID file. Defaults to @samp{"/var/run/ddclient/ddclient.pid"}. @end deftypevr @deftypevr {@code{ddclient-configuration} parameter} boolean ssl Enable SSL support. Defaults to @samp{#t}. @end deftypevr @deftypevr {@code{ddclient-configuration} parameter} string user Specifies the user name or ID that is used when running ddclient program. Defaults to @samp{"ddclient"}. @end deftypevr @deftypevr {@code{ddclient-configuration} parameter} string group Group of the user who will run the ddclient program. Defaults to @samp{"ddclient"}. @end deftypevr @deftypevr {@code{ddclient-configuration} parameter} string secret-file Secret file which will be appended to @file{ddclient.conf} file. This file contains credentials for use by ddclient. You are expected to create it manually. Defaults to @samp{"/etc/ddclient/secrets.conf"}. @end deftypevr @deftypevr {@code{ddclient-configuration} parameter} list extra-options Extra options will be appended to @file{ddclient.conf} file. Defaults to @samp{()}. @end deftypevr @c %end of fragment @node VPN Services @subsection VPN Services @cindex VPN (virtual private network) @cindex virtual private network (VPN) The @code{(gnu services vpn)} module provides services related to @dfn{virtual private networks} (VPNs). It provides a @emph{client} service for your machine to connect to a VPN, and a @emph{server} service for your machine to host a VPN. Both services use @uref{https://openvpn.net/, OpenVPN}. @deffn {Scheme Procedure} openvpn-client-service @ [#:config (openvpn-client-configuration)] Return a service that runs @command{openvpn}, a VPN daemon, as a client. @end deffn @deffn {Scheme Procedure} openvpn-server-service @ [#:config (openvpn-server-configuration)] Return a service that runs @command{openvpn}, a VPN daemon, as a server. Both can be run simultaneously. @end deffn @c %automatically generated documentation Available @code{openvpn-client-configuration} fields are: @deftypevr {@code{openvpn-client-configuration} parameter} package openvpn The OpenVPN package. @end deftypevr @deftypevr {@code{openvpn-client-configuration} parameter} string pid-file The OpenVPN pid file. Defaults to @samp{"/var/run/openvpn/openvpn.pid"}. @end deftypevr @deftypevr {@code{openvpn-client-configuration} parameter} proto proto The protocol (UDP or TCP) used to open a channel between clients and servers. Defaults to @samp{udp}. @end deftypevr @deftypevr {@code{openvpn-client-configuration} parameter} dev dev The device type used to represent the VPN connection. Defaults to @samp{tun}. @end deftypevr If you do not have some of these files (eg.@: you use a username and password), you can disable any of the following three fields by setting it to @code{'disabled}. @deftypevr {@code{openvpn-client-configuration} parameter} maybe-string ca The certificate authority to check connections against. Defaults to @samp{"/etc/openvpn/ca.crt"}. @end deftypevr @deftypevr {@code{openvpn-client-configuration} parameter} maybe-string cert The certificate of the machine the daemon is running on. It should be signed by the authority given in @code{ca}. Defaults to @samp{"/etc/openvpn/client.crt"}. @end deftypevr @deftypevr {@code{openvpn-client-configuration} parameter} maybe-string key The key of the machine the daemon is running on. It must be the key whose certificate is @code{cert}. Defaults to @samp{"/etc/openvpn/client.key"}. @end deftypevr @deftypevr {@code{openvpn-client-configuration} parameter} boolean comp-lzo? Whether to use the lzo compression algorithm. Defaults to @samp{#t}. @end deftypevr @deftypevr {@code{openvpn-client-configuration} parameter} boolean persist-key? Don't re-read key files across SIGUSR1 or --ping-restart. Defaults to @samp{#t}. @end deftypevr @deftypevr {@code{openvpn-client-configuration} parameter} boolean persist-tun? Don't close and reopen TUN/TAP device or run up/down scripts across SIGUSR1 or --ping-restart restarts. Defaults to @samp{#t}. @end deftypevr @deftypevr {@code{openvpn-client-configuration} parameter} boolean fast-io? (Experimental) Optimize TUN/TAP/UDP I/O writes by avoiding a call to poll/epoll/select prior to the write operation. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{openvpn-client-configuration} parameter} number verbosity Verbosity level. Defaults to @samp{3}. @end deftypevr @deftypevr {@code{openvpn-client-configuration} parameter} tls-auth-client tls-auth Add an additional layer of HMAC authentication on top of the TLS control channel to protect against DoS attacks. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{openvpn-client-configuration} parameter} maybe-string auth-user-pass Authenticate with server using username/password. The option is a file containing username/password on 2 lines. Do not use a file-like object as it would be added to the store and readable by any user. Defaults to @samp{'disabled}. @end deftypevr @deftypevr {@code{openvpn-client-configuration} parameter} key-usage verify-key-usage? Whether to check the server certificate has server usage extension. Defaults to @samp{#t}. @end deftypevr @deftypevr {@code{openvpn-client-configuration} parameter} bind bind? Bind to a specific local port number. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{openvpn-client-configuration} parameter} resolv-retry resolv-retry? Retry resolving server address. Defaults to @samp{#t}. @end deftypevr @deftypevr {@code{openvpn-client-configuration} parameter} openvpn-remote-list remote A list of remote servers to connect to. Defaults to @samp{()}. Available @code{openvpn-remote-configuration} fields are: @deftypevr {@code{openvpn-remote-configuration} parameter} string name Server name. Defaults to @samp{"my-server"}. @end deftypevr @deftypevr {@code{openvpn-remote-configuration} parameter} number port Port number the server listens to. Defaults to @samp{1194}. @end deftypevr @end deftypevr @c %end of automatic openvpn-client documentation @c %automatically generated documentation Available @code{openvpn-server-configuration} fields are: @deftypevr {@code{openvpn-server-configuration} parameter} package openvpn The OpenVPN package. @end deftypevr @deftypevr {@code{openvpn-server-configuration} parameter} string pid-file The OpenVPN pid file. Defaults to @samp{"/var/run/openvpn/openvpn.pid"}. @end deftypevr @deftypevr {@code{openvpn-server-configuration} parameter} proto proto The protocol (UDP or TCP) used to open a channel between clients and servers. Defaults to @samp{udp}. @end deftypevr @deftypevr {@code{openvpn-server-configuration} parameter} dev dev The device type used to represent the VPN connection. Defaults to @samp{tun}. @end deftypevr If you do not have some of these files (eg.@: you use a username and password), you can disable any of the following three fields by setting it to @code{'disabled}. @deftypevr {@code{openvpn-server-configuration} parameter} maybe-string ca The certificate authority to check connections against. Defaults to @samp{"/etc/openvpn/ca.crt"}. @end deftypevr @deftypevr {@code{openvpn-server-configuration} parameter} maybe-string cert The certificate of the machine the daemon is running on. It should be signed by the authority given in @code{ca}. Defaults to @samp{"/etc/openvpn/client.crt"}. @end deftypevr @deftypevr {@code{openvpn-server-configuration} parameter} maybe-string key The key of the machine the daemon is running on. It must be the key whose certificate is @code{cert}. Defaults to @samp{"/etc/openvpn/client.key"}. @end deftypevr @deftypevr {@code{openvpn-server-configuration} parameter} boolean comp-lzo? Whether to use the lzo compression algorithm. Defaults to @samp{#t}. @end deftypevr @deftypevr {@code{openvpn-server-configuration} parameter} boolean persist-key? Don't re-read key files across SIGUSR1 or --ping-restart. Defaults to @samp{#t}. @end deftypevr @deftypevr {@code{openvpn-server-configuration} parameter} boolean persist-tun? Don't close and reopen TUN/TAP device or run up/down scripts across SIGUSR1 or --ping-restart restarts. Defaults to @samp{#t}. @end deftypevr @deftypevr {@code{openvpn-server-configuration} parameter} boolean fast-io? (Experimental) Optimize TUN/TAP/UDP I/O writes by avoiding a call to poll/epoll/select prior to the write operation. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{openvpn-server-configuration} parameter} number verbosity Verbosity level. Defaults to @samp{3}. @end deftypevr @deftypevr {@code{openvpn-server-configuration} parameter} tls-auth-server tls-auth Add an additional layer of HMAC authentication on top of the TLS control channel to protect against DoS attacks. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{openvpn-server-configuration} parameter} number port Specifies the port number on which the server listens. Defaults to @samp{1194}. @end deftypevr @deftypevr {@code{openvpn-server-configuration} parameter} ip-mask server An ip and mask specifying the subnet inside the virtual network. Defaults to @samp{"10.8.0.0 255.255.255.0"}. @end deftypevr @deftypevr {@code{openvpn-server-configuration} parameter} cidr6 server-ipv6 A CIDR notation specifying the IPv6 subnet inside the virtual network. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{openvpn-server-configuration} parameter} string dh The Diffie-Hellman parameters file. Defaults to @samp{"/etc/openvpn/dh2048.pem"}. @end deftypevr @deftypevr {@code{openvpn-server-configuration} parameter} string ifconfig-pool-persist The file that records client IPs. Defaults to @samp{"/etc/openvpn/ipp.txt"}. @end deftypevr @deftypevr {@code{openvpn-server-configuration} parameter} gateway redirect-gateway? When true, the server will act as a gateway for its clients. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{openvpn-server-configuration} parameter} boolean client-to-client? When true, clients are allowed to talk to each other inside the VPN. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{openvpn-server-configuration} parameter} keepalive keepalive Causes ping-like messages to be sent back and forth over the link so that each side knows when the other side has gone down. @code{keepalive} requires a pair. The first element is the period of the ping sending, and the second element is the timeout before considering the other side down. @end deftypevr @deftypevr {@code{openvpn-server-configuration} parameter} number max-clients The maximum number of clients. Defaults to @samp{100}. @end deftypevr @deftypevr {@code{openvpn-server-configuration} parameter} string status The status file. This file shows a small report on current connection. It is truncated and rewritten every minute. Defaults to @samp{"/var/run/openvpn/status"}. @end deftypevr @deftypevr {@code{openvpn-server-configuration} parameter} openvpn-ccd-list client-config-dir The list of configuration for some clients. Defaults to @samp{()}. Available @code{openvpn-ccd-configuration} fields are: @deftypevr {@code{openvpn-ccd-configuration} parameter} string name Client name. Defaults to @samp{"client"}. @end deftypevr @deftypevr {@code{openvpn-ccd-configuration} parameter} ip-mask iroute Client own network Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{openvpn-ccd-configuration} parameter} ip-mask ifconfig-push Client VPN IP. Defaults to @samp{#f}. @end deftypevr @end deftypevr @c %end of automatic openvpn-server documentation @node Network File System @subsection Network File System @cindex NFS The @code{(gnu services nfs)} module provides the following services, which are most commonly used in relation to mounting or exporting directory trees as @dfn{network file systems} (NFS). While it is possible to use the individual components that together make up a Network File System service, we recommended to configure an NFS server with the @code{nfs-service-type}. @subsubheading NFS Service @cindex NFS, server The NFS service takes care of setting up all NFS component services, kernel configuration file systems, and installs configuration files in the locations that NFS expects. @defvr {Scheme Variable} nfs-service-type A service type for a complete NFS server. @end defvr @deftp {Data Type} nfs-configuration This data type represents the configuration of the NFS service and all of its subsystems. It has the following parameters: @table @asis @item @code{nfs-utils} (default: @code{nfs-utils}) The nfs-utils package to use. @item @code{nfs-versions} (default: @code{'("4.2" "4.1" "4.0")}) If a list of string values is provided, the @command{rpc.nfsd} daemon will be limited to supporting the given versions of the NFS protocol. @item @code{exports} (default: @code{'()}) This is a list of directories the NFS server should export. Each entry is a list consisting of two elements: a directory name and a string containing all options. This is an example in which the directory @file{/export} is served to all NFS clients as a read-only share: @lisp (nfs-configuration (exports '(("/export" "*(ro,insecure,no_subtree_check,crossmnt,fsid=0)")))) @end lisp @item @code{rpcmountd-port} (default: @code{#f}) The network port that the @command{rpc.mountd} daemon should use. @item @code{rpcstatd-port} (default: @code{#f}) The network port that the @command{rpc.statd} daemon should use. @item @code{rpcbind} (default: @code{rpcbind}) The rpcbind package to use. @item @code{idmap-domain} (default: @code{"localdomain"}) The local NFSv4 domain name. @item @code{nfsd-port} (default: @code{2049}) The network port that the @command{nfsd} daemon should use. @item @code{nfsd-threads} (default: @code{8}) The number of threads used by the @command{nfsd} daemon. @item @code{nfsd-tcp?} (default: @code{#t}) Whether the @command{nfsd} daemon should listen on a TCP socket. @item @code{nfsd-udp?} (default: @code{#f}) Whether the @command{nfsd} daemon should listen on a UDP socket. @item @code{pipefs-directory} (default: @code{"/var/lib/nfs/rpc_pipefs"}) The directory where the pipefs file system is mounted. @item @code{debug} (default: @code{'()"}) A list of subsystems for which debugging output should be enabled. This is a list of symbols. Any of these symbols are valid: @code{nfsd}, @code{nfs}, @code{rpc}, @code{idmap}, @code{statd}, or @code{mountd}. @end table @end deftp If you don't need a complete NFS service or prefer to build it yourself you can use the individual component services that are documented below. @subsubheading RPC Bind Service @cindex rpcbind The RPC Bind service provides a facility to map program numbers into universal addresses. Many NFS related services use this facility. Hence it is automatically started when a dependent service starts. @defvr {Scheme Variable} rpcbind-service-type A service type for the RPC portmapper daemon. @end defvr @deftp {Data Type} rpcbind-configuration Data type representing the configuration of the RPC Bind Service. This type has the following parameters: @table @asis @item @code{rpcbind} (default: @code{rpcbind}) The rpcbind package to use. @item @code{warm-start?} (default: @code{#t}) If this parameter is @code{#t}, then the daemon will read a state file on startup thus reloading state information saved by a previous instance. @end table @end deftp @subsubheading Pipefs Pseudo File System @cindex pipefs @cindex rpc_pipefs The pipefs file system is used to transfer NFS related data between the kernel and user space programs. @defvr {Scheme Variable} pipefs-service-type A service type for the pipefs pseudo file system. @end defvr @deftp {Data Type} pipefs-configuration Data type representing the configuration of the pipefs pseudo file system service. This type has the following parameters: @table @asis @item @code{mount-point} (default: @code{"/var/lib/nfs/rpc_pipefs"}) The directory to which the file system is to be attached. @end table @end deftp @subsubheading GSS Daemon Service @cindex GSSD @cindex GSS @cindex global security system The @dfn{global security system} (GSS) daemon provides strong security for RPC based protocols. Before exchanging RPC requests an RPC client must establish a security context. Typically this is done using the Kerberos command @command{kinit} or automatically at login time using PAM services (@pxref{Kerberos Services}). @defvr {Scheme Variable} gss-service-type A service type for the Global Security System (GSS) daemon. @end defvr @deftp {Data Type} gss-configuration Data type representing the configuration of the GSS daemon service. This type has the following parameters: @table @asis @item @code{nfs-utils} (default: @code{nfs-utils}) The package in which the @command{rpc.gssd} command is to be found. @item @code{pipefs-directory} (default: @code{"/var/lib/nfs/rpc_pipefs"}) The directory where the pipefs file system is mounted. @end table @end deftp @subsubheading IDMAP Daemon Service @cindex idmapd @cindex name mapper The idmap daemon service provides mapping between user IDs and user names. Typically it is required in order to access file systems mounted via NFSv4. @defvr {Scheme Variable} idmap-service-type A service type for the Identity Mapper (IDMAP) daemon. @end defvr @deftp {Data Type} idmap-configuration Data type representing the configuration of the IDMAP daemon service. This type has the following parameters: @table @asis @item @code{nfs-utils} (default: @code{nfs-utils}) The package in which the @command{rpc.idmapd} command is to be found. @item @code{pipefs-directory} (default: @code{"/var/lib/nfs/rpc_pipefs"}) The directory where the pipefs file system is mounted. @item @code{domain} (default: @code{#f}) The local NFSv4 domain name. This must be a string or @code{#f}. If it is @code{#f} then the daemon will use the host's fully qualified domain name. @item @code{verbosity} (default: @code{0}) The verbosity level of the daemon. @end table @end deftp @node Continuous Integration @subsection Continuous Integration @cindex continuous integration @uref{https://git.savannah.gnu.org/cgit/guix/guix-cuirass.git, Cuirass} is a continuous integration tool for Guix. It can be used both for development and for providing substitutes to others (@pxref{Substitutes}). The @code{(gnu services cuirass)} module provides the following service. @defvr {Scheme Procedure} cuirass-service-type The type of the Cuirass service. Its value must be a @code{cuirass-configuration} object, as described below. @end defvr To add build jobs, you have to set the @code{specifications} field of the configuration. Here is an example of a service that polls the Guix repository and builds the packages from a manifest. Some of the packages are defined in the @code{"custom-packages"} input, which is the equivalent of @env{GUIX_PACKAGE_PATH}. @lisp (define %cuirass-specs #~(list '((#:name . "my-manifest") (#:load-path-inputs . ("guix")) (#:package-path-inputs . ("custom-packages")) (#:proc-input . "guix") (#:proc-file . "build-aux/cuirass/gnu-system.scm") (#:proc . cuirass-jobs) (#:proc-args . ((subset . "manifests") (systems . ("x86_64-linux")) (manifests . (("config" . "guix/manifest.scm"))))) (#:inputs . (((#:name . "guix") (#:url . "git://git.savannah.gnu.org/guix.git") (#:load-path . ".") (#:branch . "master") (#:no-compile? . #t)) ((#:name . "config") (#:url . "https://git.example.org/config.git") (#:load-path . ".") (#:branch . "master") (#:no-compile? . #t)) ((#:name . "custom-packages") (#:url . "https://git.example.org/custom-packages.git") (#:load-path . ".") (#:branch . "master") (#:no-compile? . #t))))))) (service cuirass-service-type (cuirass-configuration (specifications %cuirass-specs))) @end lisp While information related to build jobs is located directly in the specifications, global settings for the @command{cuirass} process are accessible in other @code{cuirass-configuration} fields. @deftp {Data Type} cuirass-configuration Data type representing the configuration of Cuirass. @table @asis @item @code{log-file} (default: @code{"/var/log/cuirass.log"}) Location of the log file. @item @code{web-log-file} (default: @code{"/var/log/cuirass-web.log"}) Location of the log file used by the web interface. @item @code{queries-log-file} (default: @code{#f}) Location of the SQL queries log file. By default, SQL queries logging is disabled. @item @code{web-queries-log-file} (default: @code{#f}) Location of the web SQL queries log file. By default, web SQL queries logging is disabled. @item @code{cache-directory} (default: @code{"/var/cache/cuirass"}) Location of the repository cache. @item @code{user} (default: @code{"cuirass"}) Owner of the @code{cuirass} process. @item @code{group} (default: @code{"cuirass"}) Owner's group of the @code{cuirass} process. @item @code{interval} (default: @code{60}) Number of seconds between the poll of the repositories followed by the Cuirass jobs. @item @code{queue-size} (default: @code{1}) Size of the database writer queue. @item @code{database} (default: @code{"/var/lib/cuirass/cuirass.db"}) Location of sqlite database which contains the build results and previously added specifications. @item @code{ttl} (default: @code{(* 30 24 3600)}) Specifies the time-to-live (TTL) in seconds of garbage collector roots that are registered for build results. This means that build results are protected from garbage collection for at least @var{ttl} seconds. @item @code{port} (default: @code{8081}) Port number used by the HTTP server. @item @code{host} (default: @code{"localhost"}) Listen on the network interface for @var{host}. The default is to accept connections from localhost. @item @code{specifications} (default: @code{#~'()}) A gexp (@pxref{G-Expressions}) that evaluates to a list of specifications, where a specification is an association list (@pxref{Associations Lists,,, guile, GNU Guile Reference Manual}) whose keys are keywords (@code{#:keyword-example}) as shown in the example above. @item @code{use-substitutes?} (default: @code{#f}) This allows using substitutes to avoid building every dependencies of a job from source. @item @code{one-shot?} (default: @code{#f}) Only evaluate specifications and build derivations once. @item @code{fallback?} (default: @code{#f}) When substituting a pre-built binary fails, fall back to building packages locally. @item @code{extra-options} (default: @code{'()}) Extra options to pass when running the Cuirass processes. @item @code{cuirass} (default: @code{cuirass}) The Cuirass package to use. @end table @end deftp @node Power Management Services @subsection Power Management Services @cindex tlp @cindex power management with TLP @subsubheading TLP daemon The @code{(gnu services pm)} module provides a Guix service definition for the Linux power management tool TLP. TLP enables various powersaving modes in userspace and kernel. Contrary to @code{upower-service}, it is not a passive, monitoring tool, as it will apply custom settings each time a new power source is detected. More information can be found at @uref{https://linrunner.de/en/tlp/tlp.html, TLP home page}. @deffn {Scheme Variable} tlp-service-type The service type for the TLP tool. The default settings are optimised for battery life on most systems, but you can tweak them to your heart's content by adding a valid @code{tlp-configuration}: @lisp (service tlp-service-type (tlp-configuration (cpu-scaling-governor-on-ac (list "performance")) (sched-powersave-on-bat? #t))) @end lisp @end deffn Each parameter definition is preceded by its type; for example, @samp{boolean foo} indicates that the @code{foo} parameter should be specified as a boolean. Types starting with @code{maybe-} denote parameters that won't show up in TLP config file when their value is @code{'disabled}. @c The following documentation was initially generated by @c (generate-tlp-documentation) in (gnu services pm). Manually maintained @c documentation is better, so we shouldn't hesitate to edit below as @c needed. However if the change you want to make to this documentation @c can be done in an automated way, it's probably easier to change @c (generate-documentation) than to make it below and have to deal with @c the churn as TLP updates. Available @code{tlp-configuration} fields are: @deftypevr {@code{tlp-configuration} parameter} package tlp The TLP package. @end deftypevr @deftypevr {@code{tlp-configuration} parameter} boolean tlp-enable? Set to true if you wish to enable TLP. Defaults to @samp{#t}. @end deftypevr @deftypevr {@code{tlp-configuration} parameter} string tlp-default-mode Default mode when no power supply can be detected. Alternatives are AC and BAT. Defaults to @samp{"AC"}. @end deftypevr @deftypevr {@code{tlp-configuration} parameter} non-negative-integer disk-idle-secs-on-ac Number of seconds Linux kernel has to wait after the disk goes idle, before syncing on AC. Defaults to @samp{0}. @end deftypevr @deftypevr {@code{tlp-configuration} parameter} non-negative-integer disk-idle-secs-on-bat Same as @code{disk-idle-ac} but on BAT mode. Defaults to @samp{2}. @end deftypevr @deftypevr {@code{tlp-configuration} parameter} non-negative-integer max-lost-work-secs-on-ac Dirty pages flushing periodicity, expressed in seconds. Defaults to @samp{15}. @end deftypevr @deftypevr {@code{tlp-configuration} parameter} non-negative-integer max-lost-work-secs-on-bat Same as @code{max-lost-work-secs-on-ac} but on BAT mode. Defaults to @samp{60}. @end deftypevr @deftypevr {@code{tlp-configuration} parameter} maybe-space-separated-string-list cpu-scaling-governor-on-ac CPU frequency scaling governor on AC mode. With intel_pstate driver, alternatives are powersave and performance. With acpi-cpufreq driver, alternatives are ondemand, powersave, performance and conservative. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{tlp-configuration} parameter} maybe-space-separated-string-list cpu-scaling-governor-on-bat Same as @code{cpu-scaling-governor-on-ac} but on BAT mode. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{tlp-configuration} parameter} maybe-non-negative-integer cpu-scaling-min-freq-on-ac Set the min available frequency for the scaling governor on AC. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{tlp-configuration} parameter} maybe-non-negative-integer cpu-scaling-max-freq-on-ac Set the max available frequency for the scaling governor on AC. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{tlp-configuration} parameter} maybe-non-negative-integer cpu-scaling-min-freq-on-bat Set the min available frequency for the scaling governor on BAT. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{tlp-configuration} parameter} maybe-non-negative-integer cpu-scaling-max-freq-on-bat Set the max available frequency for the scaling governor on BAT. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{tlp-configuration} parameter} maybe-non-negative-integer cpu-min-perf-on-ac Limit the min P-state to control the power dissipation of the CPU, in AC mode. Values are stated as a percentage of the available performance. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{tlp-configuration} parameter} maybe-non-negative-integer cpu-max-perf-on-ac Limit the max P-state to control the power dissipation of the CPU, in AC mode. Values are stated as a percentage of the available performance. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{tlp-configuration} parameter} maybe-non-negative-integer cpu-min-perf-on-bat Same as @code{cpu-min-perf-on-ac} on BAT mode. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{tlp-configuration} parameter} maybe-non-negative-integer cpu-max-perf-on-bat Same as @code{cpu-max-perf-on-ac} on BAT mode. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{tlp-configuration} parameter} maybe-boolean cpu-boost-on-ac? Enable CPU turbo boost feature on AC mode. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{tlp-configuration} parameter} maybe-boolean cpu-boost-on-bat? Same as @code{cpu-boost-on-ac?} on BAT mode. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{tlp-configuration} parameter} boolean sched-powersave-on-ac? Allow Linux kernel to minimize the number of CPU cores/hyper-threads used under light load conditions. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{tlp-configuration} parameter} boolean sched-powersave-on-bat? Same as @code{sched-powersave-on-ac?} but on BAT mode. Defaults to @samp{#t}. @end deftypevr @deftypevr {@code{tlp-configuration} parameter} boolean nmi-watchdog? Enable Linux kernel NMI watchdog. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{tlp-configuration} parameter} maybe-string phc-controls For Linux kernels with PHC patch applied, change CPU voltages. An example value would be @samp{"F:V F:V F:V F:V"}. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{tlp-configuration} parameter} string energy-perf-policy-on-ac Set CPU performance versus energy saving policy on AC. Alternatives are performance, normal, powersave. Defaults to @samp{"performance"}. @end deftypevr @deftypevr {@code{tlp-configuration} parameter} string energy-perf-policy-on-bat Same as @code{energy-perf-policy-ac} but on BAT mode. Defaults to @samp{"powersave"}. @end deftypevr @deftypevr {@code{tlp-configuration} parameter} space-separated-string-list disks-devices Hard disk devices. @end deftypevr @deftypevr {@code{tlp-configuration} parameter} space-separated-string-list disk-apm-level-on-ac Hard disk advanced power management level. @end deftypevr @deftypevr {@code{tlp-configuration} parameter} space-separated-string-list disk-apm-level-on-bat Same as @code{disk-apm-bat} but on BAT mode. @end deftypevr @deftypevr {@code{tlp-configuration} parameter} maybe-space-separated-string-list disk-spindown-timeout-on-ac Hard disk spin down timeout. One value has to be specified for each declared hard disk. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{tlp-configuration} parameter} maybe-space-separated-string-list disk-spindown-timeout-on-bat Same as @code{disk-spindown-timeout-on-ac} but on BAT mode. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{tlp-configuration} parameter} maybe-space-separated-string-list disk-iosched Select IO scheduler for disk devices. One value has to be specified for each declared hard disk. Example alternatives are cfq, deadline and noop. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{tlp-configuration} parameter} string sata-linkpwr-on-ac SATA aggressive link power management (ALPM) level. Alternatives are min_power, medium_power, max_performance. Defaults to @samp{"max_performance"}. @end deftypevr @deftypevr {@code{tlp-configuration} parameter} string sata-linkpwr-on-bat Same as @code{sata-linkpwr-ac} but on BAT mode. Defaults to @samp{"min_power"}. @end deftypevr @deftypevr {@code{tlp-configuration} parameter} maybe-string sata-linkpwr-blacklist Exclude specified SATA host devices for link power management. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{tlp-configuration} parameter} maybe-on-off-boolean ahci-runtime-pm-on-ac? Enable Runtime Power Management for AHCI controller and disks on AC mode. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{tlp-configuration} parameter} maybe-on-off-boolean ahci-runtime-pm-on-bat? Same as @code{ahci-runtime-pm-on-ac} on BAT mode. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{tlp-configuration} parameter} non-negative-integer ahci-runtime-pm-timeout Seconds of inactivity before disk is suspended. Defaults to @samp{15}. @end deftypevr @deftypevr {@code{tlp-configuration} parameter} string pcie-aspm-on-ac PCI Express Active State Power Management level. Alternatives are default, performance, powersave. Defaults to @samp{"performance"}. @end deftypevr @deftypevr {@code{tlp-configuration} parameter} string pcie-aspm-on-bat Same as @code{pcie-aspm-ac} but on BAT mode. Defaults to @samp{"powersave"}. @end deftypevr @deftypevr {@code{tlp-configuration} parameter} string radeon-power-profile-on-ac Radeon graphics clock speed level. Alternatives are low, mid, high, auto, default. Defaults to @samp{"high"}. @end deftypevr @deftypevr {@code{tlp-configuration} parameter} string radeon-power-profile-on-bat Same as @code{radeon-power-ac} but on BAT mode. Defaults to @samp{"low"}. @end deftypevr @deftypevr {@code{tlp-configuration} parameter} string radeon-dpm-state-on-ac Radeon dynamic power management method (DPM). Alternatives are battery, performance. Defaults to @samp{"performance"}. @end deftypevr @deftypevr {@code{tlp-configuration} parameter} string radeon-dpm-state-on-bat Same as @code{radeon-dpm-state-ac} but on BAT mode. Defaults to @samp{"battery"}. @end deftypevr @deftypevr {@code{tlp-configuration} parameter} string radeon-dpm-perf-level-on-ac Radeon DPM performance level. Alternatives are auto, low, high. Defaults to @samp{"auto"}. @end deftypevr @deftypevr {@code{tlp-configuration} parameter} string radeon-dpm-perf-level-on-bat Same as @code{radeon-dpm-perf-ac} but on BAT mode. Defaults to @samp{"auto"}. @end deftypevr @deftypevr {@code{tlp-configuration} parameter} on-off-boolean wifi-pwr-on-ac? Wifi power saving mode. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{tlp-configuration} parameter} on-off-boolean wifi-pwr-on-bat? Same as @code{wifi-power-ac?} but on BAT mode. Defaults to @samp{#t}. @end deftypevr @deftypevr {@code{tlp-configuration} parameter} y-n-boolean wol-disable? Disable wake on LAN. Defaults to @samp{#t}. @end deftypevr @deftypevr {@code{tlp-configuration} parameter} non-negative-integer sound-power-save-on-ac Timeout duration in seconds before activating audio power saving on Intel HDA and AC97 devices. A value of 0 disables power saving. Defaults to @samp{0}. @end deftypevr @deftypevr {@code{tlp-configuration} parameter} non-negative-integer sound-power-save-on-bat Same as @code{sound-powersave-ac} but on BAT mode. Defaults to @samp{1}. @end deftypevr @deftypevr {@code{tlp-configuration} parameter} y-n-boolean sound-power-save-controller? Disable controller in powersaving mode on Intel HDA devices. Defaults to @samp{#t}. @end deftypevr @deftypevr {@code{tlp-configuration} parameter} boolean bay-poweroff-on-bat? Enable optical drive in UltraBay/MediaBay on BAT mode. Drive can be powered on again by releasing (and reinserting) the eject lever or by pressing the disc eject button on newer models. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{tlp-configuration} parameter} string bay-device Name of the optical drive device to power off. Defaults to @samp{"sr0"}. @end deftypevr @deftypevr {@code{tlp-configuration} parameter} string runtime-pm-on-ac Runtime Power Management for PCI(e) bus devices. Alternatives are on and auto. Defaults to @samp{"on"}. @end deftypevr @deftypevr {@code{tlp-configuration} parameter} string runtime-pm-on-bat Same as @code{runtime-pm-ac} but on BAT mode. Defaults to @samp{"auto"}. @end deftypevr @deftypevr {@code{tlp-configuration} parameter} boolean runtime-pm-all? Runtime Power Management for all PCI(e) bus devices, except blacklisted ones. Defaults to @samp{#t}. @end deftypevr @deftypevr {@code{tlp-configuration} parameter} maybe-space-separated-string-list runtime-pm-blacklist Exclude specified PCI(e) device addresses from Runtime Power Management. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{tlp-configuration} parameter} space-separated-string-list runtime-pm-driver-blacklist Exclude PCI(e) devices assigned to the specified drivers from Runtime Power Management. @end deftypevr @deftypevr {@code{tlp-configuration} parameter} boolean usb-autosuspend? Enable USB autosuspend feature. Defaults to @samp{#t}. @end deftypevr @deftypevr {@code{tlp-configuration} parameter} maybe-string usb-blacklist Exclude specified devices from USB autosuspend. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{tlp-configuration} parameter} boolean usb-blacklist-wwan? Exclude WWAN devices from USB autosuspend. Defaults to @samp{#t}. @end deftypevr @deftypevr {@code{tlp-configuration} parameter} maybe-string usb-whitelist Include specified devices into USB autosuspend, even if they are already excluded by the driver or via @code{usb-blacklist-wwan?}. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{tlp-configuration} parameter} maybe-boolean usb-autosuspend-disable-on-shutdown? Enable USB autosuspend before shutdown. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{tlp-configuration} parameter} boolean restore-device-state-on-startup? Restore radio device state (bluetooth, wifi, wwan) from previous shutdown on system startup. Defaults to @samp{#f}. @end deftypevr @cindex thermald @cindex CPU frequency scaling with thermald @subsubheading Thermald daemon The @code{(gnu services pm)} module provides an interface to thermald, a CPU frequency scaling service which helps prevent overheating. @defvr {Scheme Variable} thermald-service-type This is the service type for @uref{https://01.org/linux-thermal-daemon/, thermald}, the Linux Thermal Daemon, which is responsible for controlling the thermal state of processors and preventing overheating. @end defvr @deftp {Data Type} thermald-configuration Data type representing the configuration of @code{thermald-service-type}. @table @asis @item @code{ignore-cpuid-check?} (default: @code{#f}) Ignore cpuid check for supported CPU models. @item @code{thermald} (default: @var{thermald}) Package object of thermald. @end table @end deftp @node Audio Services @subsection Audio Services The @code{(gnu services audio)} module provides a service to start MPD (the Music Player Daemon). @cindex mpd @subsubheading Music Player Daemon The Music Player Daemon (MPD) is a service that can play music while being controlled from the local machine or over the network by a variety of clients. The following example shows how one might run @code{mpd} as user @code{"bob"} on port @code{6666}. It uses pulseaudio for output. @lisp (service mpd-service-type (mpd-configuration (user "bob") (port "6666"))) @end lisp @defvr {Scheme Variable} mpd-service-type The service type for @command{mpd} @end defvr @deftp {Data Type} mpd-configuration Data type representing the configuration of @command{mpd}. @table @asis @item @code{user} (default: @code{"mpd"}) The user to run mpd as. @item @code{music-dir} (default: @code{"~/Music"}) The directory to scan for music files. @item @code{playlist-dir} (default: @code{"~/.mpd/playlists"}) The directory to store playlists. @item @code{db-file} (default: @code{"~/.mpd/tag_cache"}) The location of the music database. @item @code{state-file} (default: @code{"~/.mpd/state"}) The location of the file that stores current MPD's state. @item @code{sticker-file} (default: @code{"~/.mpd/sticker.sql"}) The location of the sticker database. @item @code{port} (default: @code{"6600"}) The port to run mpd on. @item @code{address} (default: @code{"any"}) The address that mpd will bind to. To use a Unix domain socket, an absolute path can be specified here. @item @code{outputs} (default: @code{"(list (mpd-output))"}) The audio outputs that MPD can use. By default this is a single output using pulseaudio. @end table @end deftp @deftp {Data Type} mpd-output Data type representing an @command{mpd} audio output. @table @asis @item @code{name} (default: @code{"MPD"}) The name of the audio output. @item @code{type} (default: @code{"pulse"}) The type of audio output. @item @code{enabled?} (default: @code{#t}) Specifies whether this audio output is enabled when MPD is started. By default, all audio outputs are enabled. This is just the default setting when there is no state file; with a state file, the previous state is restored. @item @code{tags?} (default: @code{#t}) If set to @code{#f}, then MPD will not send tags to this output. This is only useful for output plugins that can receive tags, for example the @code{httpd} output plugin. @item @code{always-on?} (default: @code{#f}) If set to @code{#t}, then MPD attempts to keep this audio output always open. This may be useful for streaming servers, when you don’t want to disconnect all listeners even when playback is accidentally stopped. @item @code{mixer-type} This field accepts a symbol that specifies which mixer should be used for this audio output: the @code{hardware} mixer, the @code{software} mixer, the @code{null} mixer (allows setting the volume, but with no effect; this can be used as a trick to implement an external mixer External Mixer) or no mixer (@code{none}). @item @code{extra-options} (default: @code{'()}) An association list of option symbols to string values to be appended to the audio output configuration. @end table @end deftp The following example shows a configuration of @code{mpd} that provides an HTTP audio streaming output. @lisp (service mpd-service-type (mpd-configuration (outputs (list (mpd-output (name "streaming") (type "httpd") (mixer-type 'null) (extra-options `((encoder . "vorbis") (port . "8080")))))))) @end lisp @node Virtualization Services @subsection Virtualization Services The @code{(gnu services virtualization)} module provides services for the libvirt and virtlog daemons, as well as other virtualization-related services. @subsubheading Libvirt daemon @code{libvirtd} is the server side daemon component of the libvirt virtualization management system. This daemon runs on host servers and performs required management tasks for virtualized guests. @deffn {Scheme Variable} libvirt-service-type This is the type of the @uref{https://libvirt.org, libvirt daemon}. Its value must be a @code{libvirt-configuration}. @lisp (service libvirt-service-type (libvirt-configuration (unix-sock-group "libvirt") (tls-port "16555"))) @end lisp @end deffn @c Auto-generated with (generate-libvirt-documentation) Available @code{libvirt-configuration} fields are: @deftypevr {@code{libvirt-configuration} parameter} package libvirt Libvirt package. @end deftypevr @deftypevr {@code{libvirt-configuration} parameter} boolean listen-tls? Flag listening for secure TLS connections on the public TCP/IP port. You must set @code{listen} for this to have any effect. It is necessary to setup a CA and issue server certificates before using this capability. Defaults to @samp{#t}. @end deftypevr @deftypevr {@code{libvirt-configuration} parameter} boolean listen-tcp? Listen for unencrypted TCP connections on the public TCP/IP port. You must set @code{listen} for this to have any effect. Using the TCP socket requires SASL authentication by default. Only SASL mechanisms which support data encryption are allowed. This is DIGEST_MD5 and GSSAPI (Kerberos5). Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{libvirt-configuration} parameter} string tls-port Port for accepting secure TLS connections. This can be a port number, or service name. Defaults to @samp{"16514"}. @end deftypevr @deftypevr {@code{libvirt-configuration} parameter} string tcp-port Port for accepting insecure TCP connections. This can be a port number, or service name. Defaults to @samp{"16509"}. @end deftypevr @deftypevr {@code{libvirt-configuration} parameter} string listen-addr IP address or hostname used for client connections. Defaults to @samp{"0.0.0.0"}. @end deftypevr @deftypevr {@code{libvirt-configuration} parameter} boolean mdns-adv? Flag toggling mDNS advertisement of the libvirt service. Alternatively can disable for all services on a host by stopping the Avahi daemon. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{libvirt-configuration} parameter} string mdns-name Default mDNS advertisement name. This must be unique on the immediate broadcast network. Defaults to @samp{"Virtualization Host "}. @end deftypevr @deftypevr {@code{libvirt-configuration} parameter} string unix-sock-group UNIX domain socket group ownership. This can be used to allow a 'trusted' set of users access to management capabilities without becoming root. Defaults to @samp{"root"}. @end deftypevr @deftypevr {@code{libvirt-configuration} parameter} string unix-sock-ro-perms UNIX socket permissions for the R/O socket. This is used for monitoring VM status only. Defaults to @samp{"0777"}. @end deftypevr @deftypevr {@code{libvirt-configuration} parameter} string unix-sock-rw-perms UNIX socket permissions for the R/W socket. Default allows only root. If PolicyKit is enabled on the socket, the default will change to allow everyone (eg, 0777) Defaults to @samp{"0770"}. @end deftypevr @deftypevr {@code{libvirt-configuration} parameter} string unix-sock-admin-perms UNIX socket permissions for the admin socket. Default allows only owner (root), do not change it unless you are sure to whom you are exposing the access to. Defaults to @samp{"0777"}. @end deftypevr @deftypevr {@code{libvirt-configuration} parameter} string unix-sock-dir The directory in which sockets will be found/created. Defaults to @samp{"/var/run/libvirt"}. @end deftypevr @deftypevr {@code{libvirt-configuration} parameter} string auth-unix-ro Authentication scheme for UNIX read-only sockets. By default socket permissions allow anyone to connect Defaults to @samp{"polkit"}. @end deftypevr @deftypevr {@code{libvirt-configuration} parameter} string auth-unix-rw Authentication scheme for UNIX read-write sockets. By default socket permissions only allow root. If PolicyKit support was compiled into libvirt, the default will be to use 'polkit' auth. Defaults to @samp{"polkit"}. @end deftypevr @deftypevr {@code{libvirt-configuration} parameter} string auth-tcp Authentication scheme for TCP sockets. If you don't enable SASL, then all TCP traffic is cleartext. Don't do this outside of a dev/test scenario. Defaults to @samp{"sasl"}. @end deftypevr @deftypevr {@code{libvirt-configuration} parameter} string auth-tls Authentication scheme for TLS sockets. TLS sockets already have encryption provided by the TLS layer, and limited authentication is done by certificates. It is possible to make use of any SASL authentication mechanism as well, by using 'sasl' for this option Defaults to @samp{"none"}. @end deftypevr @deftypevr {@code{libvirt-configuration} parameter} optional-list access-drivers API access control scheme. By default an authenticated user is allowed access to all APIs. Access drivers can place restrictions on this. Defaults to @samp{()}. @end deftypevr @deftypevr {@code{libvirt-configuration} parameter} string key-file Server key file path. If set to an empty string, then no private key is loaded. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{libvirt-configuration} parameter} string cert-file Server key file path. If set to an empty string, then no certificate is loaded. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{libvirt-configuration} parameter} string ca-file Server key file path. If set to an empty string, then no CA certificate is loaded. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{libvirt-configuration} parameter} string crl-file Certificate revocation list path. If set to an empty string, then no CRL is loaded. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{libvirt-configuration} parameter} boolean tls-no-sanity-cert Disable verification of our own server certificates. When libvirtd starts it performs some sanity checks against its own certificates. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{libvirt-configuration} parameter} boolean tls-no-verify-cert Disable verification of client certificates. Client certificate verification is the primary authentication mechanism. Any client which does not present a certificate signed by the CA will be rejected. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{libvirt-configuration} parameter} optional-list tls-allowed-dn-list Whitelist of allowed x509 Distinguished Name. Defaults to @samp{()}. @end deftypevr @deftypevr {@code{libvirt-configuration} parameter} optional-list sasl-allowed-usernames Whitelist of allowed SASL usernames. The format for username depends on the SASL authentication mechanism. Defaults to @samp{()}. @end deftypevr @deftypevr {@code{libvirt-configuration} parameter} string tls-priority Override the compile time default TLS priority string. The default is usually @samp{"NORMAL"} unless overridden at build time. Only set this is it is desired for libvirt to deviate from the global default settings. Defaults to @samp{"NORMAL"}. @end deftypevr @deftypevr {@code{libvirt-configuration} parameter} integer max-clients Maximum number of concurrent client connections to allow over all sockets combined. Defaults to @samp{5000}. @end deftypevr @deftypevr {@code{libvirt-configuration} parameter} integer max-queued-clients Maximum length of queue of connections waiting to be accepted by the daemon. Note, that some protocols supporting retransmission may obey this so that a later reattempt at connection succeeds. Defaults to @samp{1000}. @end deftypevr @deftypevr {@code{libvirt-configuration} parameter} integer max-anonymous-clients Maximum length of queue of accepted but not yet authenticated clients. Set this to zero to turn this feature off Defaults to @samp{20}. @end deftypevr @deftypevr {@code{libvirt-configuration} parameter} integer min-workers Number of workers to start up initially. Defaults to @samp{5}. @end deftypevr @deftypevr {@code{libvirt-configuration} parameter} integer max-workers Maximum number of worker threads. If the number of active clients exceeds @code{min-workers}, then more threads are spawned, up to max_workers limit. Typically you'd want max_workers to equal maximum number of clients allowed. Defaults to @samp{20}. @end deftypevr @deftypevr {@code{libvirt-configuration} parameter} integer prio-workers Number of priority workers. If all workers from above pool are stuck, some calls marked as high priority (notably domainDestroy) can be executed in this pool. Defaults to @samp{5}. @end deftypevr @deftypevr {@code{libvirt-configuration} parameter} integer max-requests Total global limit on concurrent RPC calls. Defaults to @samp{20}. @end deftypevr @deftypevr {@code{libvirt-configuration} parameter} integer max-client-requests Limit on concurrent requests from a single client connection. To avoid one client monopolizing the server this should be a small fraction of the global max_requests and max_workers parameter. Defaults to @samp{5}. @end deftypevr @deftypevr {@code{libvirt-configuration} parameter} integer admin-min-workers Same as @code{min-workers} but for the admin interface. Defaults to @samp{1}. @end deftypevr @deftypevr {@code{libvirt-configuration} parameter} integer admin-max-workers Same as @code{max-workers} but for the admin interface. Defaults to @samp{5}. @end deftypevr @deftypevr {@code{libvirt-configuration} parameter} integer admin-max-clients Same as @code{max-clients} but for the admin interface. Defaults to @samp{5}. @end deftypevr @deftypevr {@code{libvirt-configuration} parameter} integer admin-max-queued-clients Same as @code{max-queued-clients} but for the admin interface. Defaults to @samp{5}. @end deftypevr @deftypevr {@code{libvirt-configuration} parameter} integer admin-max-client-requests Same as @code{max-client-requests} but for the admin interface. Defaults to @samp{5}. @end deftypevr @deftypevr {@code{libvirt-configuration} parameter} integer log-level Logging level. 4 errors, 3 warnings, 2 information, 1 debug. Defaults to @samp{3}. @end deftypevr @deftypevr {@code{libvirt-configuration} parameter} string log-filters Logging filters. A filter allows to select a different logging level for a given category of logs. The format for a filter is one of: @itemize @bullet @item x:name @item x:+name @end itemize where @code{name} is a string which is matched against the category given in the @code{VIR_LOG_INIT()} at the top of each libvirt source file, e.g., @samp{"remote"}, @samp{"qemu"}, or @samp{"util.json"} (the name in the filter can be a substring of the full category name, in order to match multiple similar categories), the optional @samp{"+"} prefix tells libvirt to log stack trace for each message matching name, and @code{x} is the minimal level where matching messages should be logged: @itemize @bullet @item 1: DEBUG @item 2: INFO @item 3: WARNING @item 4: ERROR @end itemize Multiple filters can be defined in a single filters statement, they just need to be separated by spaces. Defaults to @samp{"3:remote 4:event"}. @end deftypevr @deftypevr {@code{libvirt-configuration} parameter} string log-outputs Logging outputs. An output is one of the places to save logging information. The format for an output can be: @table @code @item x:stderr output goes to stderr @item x:syslog:name use syslog for the output and use the given name as the ident @item x:file:file_path output to a file, with the given filepath @item x:journald output to journald logging system @end table In all case the x prefix is the minimal level, acting as a filter @itemize @bullet @item 1: DEBUG @item 2: INFO @item 3: WARNING @item 4: ERROR @end itemize Multiple outputs can be defined, they just need to be separated by spaces. Defaults to @samp{"3:stderr"}. @end deftypevr @deftypevr {@code{libvirt-configuration} parameter} integer audit-level Allows usage of the auditing subsystem to be altered @itemize @bullet @item 0: disable all auditing @item 1: enable auditing, only if enabled on host @item 2: enable auditing, and exit if disabled on host. @end itemize Defaults to @samp{1}. @end deftypevr @deftypevr {@code{libvirt-configuration} parameter} boolean audit-logging Send audit messages via libvirt logging infrastructure. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{libvirt-configuration} parameter} optional-string host-uuid Host UUID. UUID must not have all digits be the same. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{libvirt-configuration} parameter} string host-uuid-source Source to read host UUID. @itemize @bullet @item @code{smbios}: fetch the UUID from @code{dmidecode -s system-uuid} @item @code{machine-id}: fetch the UUID from @code{/etc/machine-id} @end itemize If @code{dmidecode} does not provide a valid UUID a temporary UUID will be generated. Defaults to @samp{"smbios"}. @end deftypevr @deftypevr {@code{libvirt-configuration} parameter} integer keepalive-interval A keepalive message is sent to a client after @code{keepalive_interval} seconds of inactivity to check if the client is still responding. If set to -1, libvirtd will never send keepalive requests; however clients can still send them and the daemon will send responses. Defaults to @samp{5}. @end deftypevr @deftypevr {@code{libvirt-configuration} parameter} integer keepalive-count Maximum number of keepalive messages that are allowed to be sent to the client without getting any response before the connection is considered broken. In other words, the connection is automatically closed approximately after @code{keepalive_interval * (keepalive_count + 1)} seconds since the last message received from the client. When @code{keepalive-count} is set to 0, connections will be automatically closed after @code{keepalive-interval} seconds of inactivity without sending any keepalive messages. Defaults to @samp{5}. @end deftypevr @deftypevr {@code{libvirt-configuration} parameter} integer admin-keepalive-interval Same as above but for admin interface. Defaults to @samp{5}. @end deftypevr @deftypevr {@code{libvirt-configuration} parameter} integer admin-keepalive-count Same as above but for admin interface. Defaults to @samp{5}. @end deftypevr @deftypevr {@code{libvirt-configuration} parameter} integer ovs-timeout Timeout for Open vSwitch calls. The @code{ovs-vsctl} utility is used for the configuration and its timeout option is set by default to 5 seconds to avoid potential infinite waits blocking libvirt. Defaults to @samp{5}. @end deftypevr @c %end of autogenerated docs @subsubheading Virtlog daemon The virtlogd service is a server side daemon component of libvirt that is used to manage logs from virtual machine consoles. This daemon is not used directly by libvirt client applications, rather it is called on their behalf by @code{libvirtd}. By maintaining the logs in a standalone daemon, the main @code{libvirtd} daemon can be restarted without risk of losing logs. The @code{virtlogd} daemon has the ability to re-exec() itself upon receiving @code{SIGUSR1}, to allow live upgrades without downtime. @deffn {Scheme Variable} virtlog-service-type This is the type of the virtlog daemon. Its value must be a @code{virtlog-configuration}. @lisp (service virtlog-service-type (virtlog-configuration (max-clients 1000))) @end lisp @end deffn @deftypevr {@code{virtlog-configuration} parameter} integer log-level Logging level. 4 errors, 3 warnings, 2 information, 1 debug. Defaults to @samp{3}. @end deftypevr @deftypevr {@code{virtlog-configuration} parameter} string log-filters Logging filters. A filter allows to select a different logging level for a given category of logs The format for a filter is one of: @itemize @bullet @item x:name @item x:+name @end itemize where @code{name} is a string which is matched against the category given in the @code{VIR_LOG_INIT()} at the top of each libvirt source file, e.g., "remote", "qemu", or "util.json" (the name in the filter can be a substring of the full category name, in order to match multiple similar categories), the optional "+" prefix tells libvirt to log stack trace for each message matching name, and @code{x} is the minimal level where matching messages should be logged: @itemize @bullet @item 1: DEBUG @item 2: INFO @item 3: WARNING @item 4: ERROR @end itemize Multiple filters can be defined in a single filters statement, they just need to be separated by spaces. Defaults to @samp{"3:remote 4:event"}. @end deftypevr @deftypevr {@code{virtlog-configuration} parameter} string log-outputs Logging outputs. An output is one of the places to save logging information The format for an output can be: @table @code @item x:stderr output goes to stderr @item x:syslog:name use syslog for the output and use the given name as the ident @item x:file:file_path output to a file, with the given filepath @item x:journald output to journald logging system @end table In all case the x prefix is the minimal level, acting as a filter @itemize @bullet @item 1: DEBUG @item 2: INFO @item 3: WARNING @item 4: ERROR @end itemize Multiple outputs can be defined, they just need to be separated by spaces. Defaults to @samp{"3:stderr"}. @end deftypevr @deftypevr {@code{virtlog-configuration} parameter} integer max-clients Maximum number of concurrent client connections to allow over all sockets combined. Defaults to @samp{1024}. @end deftypevr @deftypevr {@code{virtlog-configuration} parameter} integer max-size Maximum file size before rolling over. Defaults to @samp{2MB} @end deftypevr @deftypevr {@code{virtlog-configuration} parameter} integer max-backups Maximum number of backup files to keep. Defaults to @samp{3} @end deftypevr @anchor{transparent-emulation-qemu} @subsubheading Transparent Emulation with QEMU @cindex emulation @cindex @code{binfmt_misc} @code{qemu-binfmt-service-type} provides support for transparent emulation of program binaries built for different architectures---e.g., it allows you to transparently execute an ARMv7 program on an x86_64 machine. It achieves this by combining the @uref{https://www.qemu.org, QEMU} emulator and the @code{binfmt_misc} feature of the kernel Linux. This feature only allows you to emulate GNU/Linux on a different architecture, but see below for GNU/Hurd support. @defvr {Scheme Variable} qemu-binfmt-service-type This is the type of the QEMU/binfmt service for transparent emulation. Its value must be a @code{qemu-binfmt-configuration} object, which specifies the QEMU package to use as well as the architecture we want to emulated: @lisp (service qemu-binfmt-service-type (qemu-binfmt-configuration (platforms (lookup-qemu-platforms "arm" "aarch64")))) @end lisp In this example, we enable transparent emulation for the ARM and aarch64 platforms. Running @code{herd stop qemu-binfmt} turns it off, and running @code{herd start qemu-binfmt} turns it back on (@pxref{Invoking herd, the @command{herd} command,, shepherd, The GNU Shepherd Manual}). @end defvr @deftp {Data Type} qemu-binfmt-configuration This is the configuration for the @code{qemu-binfmt} service. @table @asis @item @code{platforms} (default: @code{'()}) The list of emulated QEMU platforms. Each item must be a @dfn{platform object} as returned by @code{lookup-qemu-platforms} (see below). @item @code{guix-support?} (default: @code{#f}) When it is true, QEMU and all its dependencies are added to the build environment of @command{guix-daemon} (@pxref{Invoking guix-daemon, @option{--chroot-directory} option}). This allows the @code{binfmt_misc} handlers to be used within the build environment, which in turn means that you can transparently build programs for another architecture. For example, let's suppose you're on an x86_64 machine and you have this service: @lisp (service qemu-binfmt-service-type (qemu-binfmt-configuration (platforms (lookup-qemu-platforms "arm")) (guix-support? #t))) @end lisp You can run: @example guix build -s armhf-linux inkscape @end example @noindent and it will build Inkscape for ARMv7 @emph{as if it were a native build}, transparently using QEMU to emulate the ARMv7 CPU. Pretty handy if you'd like to test a package build for an architecture you don't have access to! @item @code{qemu} (default: @code{qemu}) The QEMU package to use. @end table @end deftp @deffn {Scheme Procedure} lookup-qemu-platforms @var{platforms}@dots{} Return the list of QEMU platform objects corresponding to @var{platforms}@dots{}. @var{platforms} must be a list of strings corresponding to platform names, such as @code{"arm"}, @code{"sparc"}, @code{"mips64el"}, and so on. @end deffn @deffn {Scheme Procedure} qemu-platform? @var{obj} Return true if @var{obj} is a platform object. @end deffn @deffn {Scheme Procedure} qemu-platform-name @var{platform} Return the name of @var{platform}---a string such as @code{"arm"}. @end deffn @subsubheading The Hurd in a Virtual Machine @cindex @code{hurd} @cindex the Hurd @cindex childhurd Service @code{hurd-vm} provides support for running GNU/Hurd in a virtual machine (VM), a so-called @dfn{childhurd}. This service is meant to be used on GNU/Linux and the given GNU/Hurd operating system configuration is cross-compiled. The virtual machine is a Shepherd service that can be referred to by the names @code{hurd-vm} and @code{childhurd} and be controlled with commands such as: @example herd start hurd-vm herd stop childhurd @end example When the service is running, you can view its console by connecting to it with a VNC client, for example with: @example guix environment --ad-hoc tigervnc-client -- \ vncviewer localhost:5900 @end example The default configuration (see @code{hurd-vm-configuration} below) spawns a secure shell (SSH) server in your GNU/Hurd system, which QEMU (the virtual machine emulator) redirects to port 10222 on the host. Thus, you can connect over SSH to the childhurd with: @example ssh root@@localhost -p 10022 @end example The childhurd is volatile and stateless: it starts with a fresh root file system every time you restart it. By default though, all the files under @file{/etc/childhurd} on the host are copied as is to the root file system of the childhurd when it boots. This allows you to initialize ``secrets'' inside the VM: SSH host keys, authorized substitute keys, and so on---see the explanation of @code{secret-root} below. @defvr {Scheme Variable} hurd-vm-service-type This is the type of the Hurd in a Virtual Machine service. Its value must be a @code{hurd-vm-configuration} object, which specifies the operating system (@pxref{operating-system Reference}) and the disk size for the Hurd Virtual Machine, the QEMU package to use as well as the options for running it. For example: @lisp (service hurd-vm-service-type (hurd-vm-configuration (disk-size (* 5000 (expt 2 20))) ;5G (memory-size 1024))) ;1024MiB @end lisp would create a disk image big enough to build GNU@tie{}Hello, with some extra memory. @end defvr @deftp {Data Type} hurd-vm-configuration The data type representing the configuration for @code{hurd-vm-service-type}. @table @asis @item @code{os} (default: @var{%hurd-vm-operating-system}) The operating system to instantiate. This default is bare-bones with a permissive OpenSSH secure shell daemon listening on port 2222 (@pxref{Networking Services, @code{openssh-service-type}}). @item @code{qemu} (default: @code{qemu-minimal}) The QEMU package to use. @item @code{image} (default: @var{hurd-vm-disk-image}) The procedure used to build the disk-image built from this configuration. @item @code{disk-size} (default: @code{'guess}) The size of the disk image. @item @code{memory-size} (default: @code{512}) The memory size of the Virtual Machine in mebibytes. @item @code{options} (default: @code{'("--snapshot")}) The extra options for running QEMU. @item @code{id} (default: @code{#f}) If set, a non-zero positive integer used to parameterize Childhurd instances. It is appended to the service's name, e.g. @code{childhurd1}. @item @code{net-options} (default: @var{hurd-vm-net-options}) The procedure used to produce the list of QEMU networking options. By default, it produces @lisp '("--device" "rtl8139,netdev=net0" "--netdev" "user,id=net0\ ,hostfwd=tcp:127.0.0.1:@var{secrets-port}-:1004\ ,hostfwd=tcp:127.0.0.1:@var{ssh-port}-:2222\ ,hostfwd=tcp:127.0.0.1:@var{vnc-port}-:5900") @end lisp with forwarded ports: @example @var{secrets-port}: @code{(+ 11004 (* 1000 @var{ID}))} @var{ssh-port}: @code{(+ 10022 (* 1000 @var{ID}))} @var{vnc-port}: @code{(+ 15900 (* 1000 @var{ID}))} @end example @item @code{secret-root} (default: @file{/etc/childhurd}) The root directory with out-of-band secrets to be installed into the childhurd once it runs. Childhurds are volatile which means that on every startup, secrets such as the SSH host keys and Guix signing key are recreated. If the @file{/etc/childhurd} directory does not exist, the @code{secret-service} running in the Childhurd will be sent an empty list of secrets. By default, the service automatically populates @file{/etc/childhurd} with the following non-volatile secrets, unless they already exist: @example /etc/childhurd/etc/guix/acl /etc/childhurd/etc/guix/signing-key.pub /etc/childhurd/etc/guix/signing-key.sec /etc/childhurd/etc/ssh/ssh_host_ed25519_key /etc/childhurd/etc/ssh/ssh_host_ecdsa_key /etc/childhurd/etc/ssh/ssh_host_ed25519_key.pub /etc/childhurd/etc/ssh/ssh_host_ecdsa_key.pub @end example These files are automatically sent to the guest Hurd VM when it boots, including permissions. @cindex childhurd, offloading @cindex Hurd, offloading Having these files in place means that only a couple of things are missing to allow the host to offload @code{i586-gnu} builds to the childhurd: @enumerate @item Authorizing the childhurd's key on the host so that the host accepts build results coming from the childhurd, which can be done like so: @example guix archive --authorize < \ /etc/childhurd/etc/guix/signing-key.pub @end example @item Adding the childhurd to @file{/etc/guix/machines.scm} (@pxref{Daemon Offload Setup}). @end enumerate We're working towards making that happen automatically---get in touch with us at @email{guix-devel@@gnu.org} to discuss it! @end table @end deftp Note that by default the VM image is volatile, i.e., once stopped the contents are lost. If you want a stateful image instead, override the configuration's @code{image} and @code{options} without the @code{--snapshot} flag using something along these lines: @lisp (service hurd-vm-service-type (hurd-vm-configuration (image (const "/out/of/store/writable/hurd.img")) (options '()))) @end lisp @subsubheading Ganeti @cindex ganeti @quotation Note This service is considered experimental. Configuration options may be changed in a backwards-incompatible manner, and not all features have been thorougly tested. Users of this service are encouraged to share their experience at @email{guix-devel@@gnu.org}. @end quotation Ganeti is a virtual machine management system. It is designed to keep virtual machines running on a cluster of servers even in the event of hardware failures, and to make maintenance and recovery tasks easy. It consists of multiple services which are described later in this section. In addition to the Ganeti service, you will need the OpenSSH service (@pxref{Networking Services, @code{openssh-service-type}}), and update the @file{/etc/hosts} file (@pxref{operating-system Reference, @code{hosts-file}}) with the cluster name and address (or use a DNS server). All nodes participating in a Ganeti cluster should have the same Ganeti and @file{/etc/hosts} configuration. Here is an example configuration for a Ganeti cluster node that supports multiple storage backends, and installs the @code{debootstrap} and @code{guix} @dfn{OS providers}: @lisp (use-package-modules virtualization) (use-service-modules base ganeti networking ssh) (operating-system ;; @dots{} (host-name "node1") (hosts-file (plain-file "hosts" (format #f " 127.0.0.1 localhost ::1 localhost 192.168.1.200 ganeti.example.com 192.168.1.201 node1.example.com node1 192.168.1.202 node2.example.com node2 "))) ;; Install QEMU so we can use KVM-based instances, and LVM, DRBD and Ceph ;; in order to use the "plain", "drbd" and "rbd" storage backends. (packages (append (map specification->package '("qemu" "lvm2" "drbd-utils" "ceph" ;; Add the debootstrap and guix OS providers. "ganeti-instance-guix" "ganeti-instance-debootstrap")) %base-packages)) (services (append (list (static-networking-service "eth0" "192.168.1.201" #:netmask "255.255.255.0" #:gateway "192.168.1.254" #:name-servers '("192.168.1.252" "192.168.1.253")) ;; Ganeti uses SSH to communicate between nodes. (service openssh-service-type (openssh-configuration (permit-root-login 'without-password))) (service ganeti-service-type (ganeti-configuration ;; This list specifies allowed file system paths ;; for storing virtual machine images. (file-storage-paths '("/srv/ganeti/file-storage")) ;; This variable configures a single "variant" for ;; both Debootstrap and Guix that works with KVM. (os %default-ganeti-os)))) %base-services))) @end lisp Users are advised to read the @url{http://docs.ganeti.org/ganeti/master/html/admin.html,Ganeti administrators guide} to learn about the various cluster options and day-to-day operations. There is also a @url{https://guix.gnu.org/blog/2020/running-a-ganeti-cluster-on-guix/,blog post} describing how to configure and initialize a small cluster. @defvr {Scheme Variable} ganeti-service-type This is a service type that includes all the various services that Ganeti nodes should run. Its value is a @code{ganeti-configuration} object that defines the package to use for CLI operations, as well as configuration for the various daemons. Allowed file storage paths and available guest operating systems are also configured through this data type. @end defvr @deftp {Data Type} ganeti-configuration The @code{ganeti} service takes the following configuration options: @table @asis @item @code{ganeti} (default: @code{ganeti}) The @code{ganeti} package to use. It will be installed to the system profile and make @command{gnt-cluster}, @command{gnt-instance}, etc available. Note that the value specified here does not affect the other services as each refer to a specific @code{ganeti} package (see below). @item @code{noded-configuration} (default: @code{(ganeti-noded-configuration)}) @itemx @code{confd-configuration} (default: @code{(ganeti-confd-configuration)}) @itemx @code{wconfd-configuration} (default: @code{(ganeti-wconfd-configuration)}) @itemx @code{luxid-configuration} (default: @code{(ganeti-luxid-configuration)}) @itemx @code{rapi-configuration} (default: @code{(ganeti-rapi-configuration)}) @itemx @code{kvmd-configuration} (default: @code{(ganeti-kvmd-configuration)}) @itemx @code{mond-configuration} (default: @code{(ganeti-mond-configuration)}) @itemx @code{metad-configuration} (default: @code{(ganeti-metad-configuration)}) @itemx @code{watcher-configuration} (default: @code{(ganeti-watcher-configuration)}) @itemx @code{cleaner-configuration} (default: @code{(ganeti-cleaner-configuration)}) These options control the various daemons and cron jobs that are distributed with Ganeti. The possible values for these are described in detail below. To override a setting, you must use the configuration type for that service: @lisp (service ganeti-service-type (ganeti-configuration (rapi-configuration (ganeti-rapi-configuration (interface "eth1")))) (watcher-configuration (ganeti-watcher-configuration (rapi-ip "10.0.0.1")))) @end lisp @item @code{file-storage-paths} (default: @code{'()}) List of allowed directories for file storage backend. @item @code{os} (default: @code{%default-ganeti-os}) List of @code{} records. @end table In essence @code{ganeti-service-type} is shorthand for declaring each service individually: @lisp (service ganeti-noded-service-type) (service ganeti-confd-service-type) (service ganeti-wconfd-service-type) (service ganeti-luxid-service-type) (service ganeti-kvmd-service-type) (service ganeti-mond-service-type) (service ganeti-metad-service-type) (service ganeti-watcher-service-type) (service ganeti-cleaner-service-type) @end lisp Plus a service extension for @code{etc-service-type} that configures the file storage backend and OS variants. @end deftp @deftp {Data Type} ganeti-os This data type is suitable for passing to the @code{os} parameter of @code{ganeti-configuration}. It takes the following parameters: @table @asis @item @code{name} The name for this OS provider. It is only used to specify where the configuration ends up. Setting it to ``debootstrap'' will create @file{/etc/ganeti/instance-debootstrap}. @item @code{extension} The file extension for variants of this OS type. For example @file{.conf} or @file{.scm}. @item @code{variants} (default: @code{'()}) List of @code{ganeti-os-variant} objects for this OS. @end table @end deftp @deftp {Data Type} ganeti-os-variant This is the data type for a Ganeti OS variant. It takes the following parameters: @table @asis @item @code{name} The name of this variant. @item @code{configuration} A configuration file for this variant. @end table @end deftp @defvr {Scheme Variable} %default-debootstrap-hooks This variable contains hooks to configure networking and the GRUB bootloader. @end defvr @defvr {Scheme Variable} %default-debootstrap-extra-pkgs This variable contains a list of packages suitable for a fully-virtualized guest. @end defvr @deftp {Data Type} debootstrap-configuration This data type creates configuration files suitable for the debootstrap OS provider. @table @asis @item @code{hooks} (default: @code{%default-debootstrap-hooks}) When not @code{#f}, this must be a G-expression that specifies a directory with scripts that will run when the OS is installed. It can also be a list of @code{(name . file-like)} pairs. For example: @lisp `((99-hello-world . ,(plain-file "#!/bin/sh\necho Hello, World"))) @end lisp That will create a directory with one executable named @code{99-hello-world} and run it every time this variant is installed. If set to @code{#f}, hooks in @file{/etc/ganeti/instance-debootstrap/hooks} will be used, if any. @item @code{proxy} (default: @code{#f}) Optional HTTP proxy to use. @item @code{mirror} (default: @code{#f}) The Debian mirror. Typically something like @code{http://ftp.no.debian.org/debian}. The default varies depending on the distribution. @item @code{arch} (default: @code{#f}) The dpkg architecture. Set to @code{armhf} to debootstrap an ARMv7 instance on an AArch64 host. Default is to use the current system architecture. @item @code{suite} (default: @code{"stable"}) When set, this must be a Debian distribution ``suite'' such as @code{buster} or @code{focal}. If set to @code{#f}, the default for the OS provider is used. @item @code{extra-pkgs} (default: @code{%default-debootstrap-extra-pkgs}) List of extra packages that will get installed by dpkg in addition to the minimal system. @item @code{components} (default: @code{#f}) When set, must be a list of Debian repository ``components''. For example @code{'("main" "contrib")}. @item @code{generate-cache?} (default: @code{#t}) Whether to automatically cache the generated debootstrap archive. @item @code{clean-cache} (default: @code{14}) Discard the cache after this amount of days. Use @code{#f} to never clear the cache. @item @code{partition-style} (default: @code{'msdos}) The type of partition to create. When set, it must be one of @code{'msdos}, @code{'none} or a string. @item @code{partition-alignment} (default: @code{2048}) Alignment of the partition in sectors. @end table @end deftp @deffn {Scheme Procedure} debootstrap-variant @var{name} @var{configuration} This is a helper procedure that creates a @code{ganeti-os-variant} record. It takes two parameters: a name and a @code{debootstrap-configuration} object. @end deffn @deffn {Scheme Procedure} debootstrap-os @var{variants}@dots{} This is a helper procedure that creates a @code{ganeti-os} record. It takes a list of variants created with @code{debootstrap-variant}. @end deffn @deffn {Scheme Procedure} guix-variant @var{name} @var{configuration} This is a helper procedure that creates a @code{ganeti-os-variant} record for use with the Guix OS provider. It takes a name and a G-expression that returns a ``file-like'' (@pxref{G-Expressions, file-like objects}) object containing a Guix System configuration. @end deffn @deffn {Scheme Procedure} guix-os @var{variants}@dots{} This is a helper procedure that creates a @code{ganeti-os} record. It takes a list of variants produced by @code{guix-variant}. @end deffn @defvr {Scheme Variable} %default-debootstrap-variants This is a convenience variable to make the debootstrap provider work ``out of the box'' without users having to declare variants manually. It contains a single debootstrap variant with the default configuration: @lisp (list (debootstrap-variant "default" (debootstrap-configuration))) @end lisp @end defvr @defvr {Scheme Variable} %default-guix-variants This is a convenience variable to make the Guix OS provider work without additional configuration. It creates a virtual machine that has an SSH server, a serial console, and authorizes the Ganeti hosts SSH keys. @lisp (list (guix-variant "default" (file-append ganeti-instance-guix "/share/doc/ganeti-instance-guix/examples/dynamic.scm"))) @end lisp @end defvr Users can implement support for OS providers unbeknownst to Guix by extending the @code{ganeti-os} and @code{ganeti-os-variant} records appropriately. For example: @lisp (ganeti-os (name "custom") (extension ".conf") (variants (list (ganeti-os-variant (name "foo") (configuration (plain-file "bar" "this is fine")))))) @end lisp That creates @file{/etc/ganeti/instance-custom/variants/foo.conf} which points to a file in the store with contents @code{this is fine}. It also creates @file{/etc/ganeti/instance-custom/variants/variants.list} with contents @code{foo}. Obviously this may not work for all OS providers out there. If you find the interface limiting, please reach out to @email{guix-devel@@gnu.org}. The rest of this section documents the various services that are included by @code{ganeti-service-type}. @defvr {Scheme Variable} ganeti-noded-service-type @command{ganeti-noded} is the daemon responsible for node-specific functions within the Ganeti system. The value of this service must be a @code{ganeti-noded-configuration} object. @end defvr @deftp {Data Type} ganeti-noded-configuration This is the configuration for the @code{ganeti-noded} service. @table @asis @item @code{ganeti} (default: @code{ganeti}) The @code{ganeti} package to use for this service. @item @code{port} (default: @code{1811}) The TCP port on which the node daemon listens for network requests. @item @code{address} (default: @code{"0.0.0.0"}) The network address that the daemon will bind to. The default address means bind to all available addresses. @item @code{interface} (default: @code{#f}) When this is set, it must be a specific network interface (e.g.@: @code{eth0}) that the daemon will bind to. @item @code{max-clients} (default: @code{20}) This sets a limit on the maximum number of simultaneous client connections that the daemon will handle. Connections above this count are accepted, but no responses will be sent until enough connections have closed. @item @code{ssl?} (default: @code{#t}) Whether to use SSL/TLS to encrypt network communications. The certificate is automatically provisioned by the cluster and can be rotated with @command{gnt-cluster renew-crypto}. @item @code{ssl-key} (default: @file{"/var/lib/ganeti/server.pem"}) This can be used to provide a specific encryption key for TLS communications. @item @code{ssl-cert} (default: @file{"/var/lib/ganeti/server.pem"}) This can be used to provide a specific certificate for TLS communications. @item @code{debug?} (default: @code{#f}) When true, the daemon performs additional logging for debugging purposes. Note that this will leak encryption details to the log files, use with caution. @end table @end deftp @defvr {Scheme Variable} ganeti-confd-service-type @command{ganeti-confd} answers queries related to the configuration of a Ganeti cluster. The purpose of this daemon is to have a highly available and fast way to query cluster configuration values. It is automatically active on all @dfn{master candidates}. The value of this service must be a @code{ganeti-confd-configuration} object. @end defvr @deftp {Data Type} ganeti-confd-configuration This is the configuration for the @code{ganeti-confd} service. @table @asis @item @code{ganeti} (default: @code{ganeti}) The @code{ganeti} package to use for this service. @item @code{port} (default: @code{1814}) The UDP port on which to listen for network requests. @item @code{address} (default: @code{"0.0.0.0"}) Network address that the daemon will bind to. @item @code{debug?} (default: @code{#f}) When true, the daemon performs additional logging for debugging purposes. @end table @end deftp @defvr {Scheme Variable} ganeti-wconfd-service-type @command{ganeti-wconfd} is the daemon that has authoritative knowledge about the cluster configuration and is the only entity that can accept changes to it. All jobs that need to modify the configuration will do so by sending appropriate requests to this daemon. It only runs on the @dfn{master node} and will automatically disable itself on other nodes. The value of this service must be a @code{ganeti-wconfd-configuration} object. @end defvr @deftp {Data Type} ganeti-wconfd-configuration This is the configuration for the @code{ganeti-wconfd} service. @table @asis @item @code{ganeti} (default: @code{ganeti}) The @code{ganeti} package to use for this service. @item @code{no-voting?} (default: @code{#f}) The daemon will refuse to start if the majority of cluster nodes does not agree that it is running on the master node. Set to @code{#t} to start even if a quorum can not be reached (dangerous, use with caution). @item @code{debug?} (default: @code{#f}) When true, the daemon performs additional logging for debugging purposes. @end table @end deftp @defvr {Scheme Variable} ganeti-luxid-service-type @command{ganeti-luxid} is a daemon used to answer queries related to the configuration and the current live state of a Ganeti cluster. Additionally, it is the authoritative daemon for the Ganeti job queue. Jobs can be submitted via this daemon and it schedules and starts them. It takes a @code{ganeti-luxid-configuration} object. @end defvr @deftp {Data Type} ganeti-luxid-configuration This is the configuration for the @code{ganeti-wconfd} service. @table @asis @item @code{ganeti} (default: @code{ganeti}) The @code{ganeti} package to use for this service. @item @code{no-voting?} (default: @code{#f}) The daemon will refuse to start if it cannot verify that the majority of cluster nodes believes that it is running on the master node. Set to @code{#t} to ignore such checks and start anyway (this can be dangerous). @item @code{debug?} (default: @code{#f}) When true, the daemon performs additional logging for debugging purposes. @end table @end deftp @defvr {Scheme Variable} ganeti-rapi-service-type @command{ganeti-rapi} provides a remote API for Ganeti clusters. It runs on the master node and can be used to perform cluster actions programmatically via a JSON-based RPC protocol. Most query operations are allowed without authentication (unless @var{require-authentication?} is set), whereas write operations require explicit authorization via the @file{/var/lib/ganeti/rapi/users} file. See the @url{http://docs.ganeti.org/ganeti/master/html/rapi.html, Ganeti Remote API documentation} for more information. The value of this service must be a @code{ganeti-rapi-configuration} object. @end defvr @deftp {Data Type} ganeti-rapi-configuration This is the configuration for the @code{ganeti-rapi} service. @table @asis @item @code{ganeti} (default: @code{ganeti}) The @code{ganeti} package to use for this service. @item @code{require-authentication?} (default: @code{#f}) Whether to require authentication even for read-only operations. @item @code{port} (default: @code{5080}) The TCP port on which to listen to API requests. @item @code{address} (default: @code{"0.0.0.0"}) The network address that the service will bind to. By default it listens on all configured addresses. @item @code{interface} (default: @code{#f}) When set, it must specify a specific network interface such as @code{eth0} that the daemon will bind to. @item @code{max-clients} (default: @code{20}) The maximum number of simultaneous client requests to handle. Further connections are allowed, but no responses are sent until enough connections have closed. @item @code{ssl?} (default: @code{#t}) Whether to use SSL/TLS encryption on the RAPI port. @item @code{ssl-key} (default: @file{"/var/lib/ganeti/server.pem"}) This can be used to provide a specific encryption key for TLS communications. @item @code{ssl-cert} (default: @file{"/var/lib/ganeti/server.pem"}) This can be used to provide a specific certificate for TLS communications. @item @code{debug?} (default: @code{#f}) When true, the daemon performs additional logging for debugging purposes. Note that this will leak encryption details to the log files, use with caution. @end table @end deftp @defvr {Scheme Variable} ganeti-kvmd-service-type @command{ganeti-kvmd} is responsible for determining whether a given KVM instance was shut down by an administrator or a user. Normally Ganeti will restart an instance that was not stopped through Ganeti itself. If the cluster option @code{user_shutdown} is true, this daemon monitors the @code{QMP} socket provided by QEMU and listens for shutdown events, and marks the instance as @dfn{USER_down} instead of @dfn{ERROR_down} when it shuts down gracefully by itself. It takes a @code{ganeti-kvmd-configuration} object. @end defvr @deftp {Data Type} ganeti-kvmd-configuration @table @asis @item @code{ganeti} (default: @code{ganeti}) The @code{ganeti} package to use for this service. @item @code{debug?} (default: @code{#f}) When true, the daemon performs additional logging for debugging purposes. @end table @end deftp @defvr {Scheme Variable} ganeti-mond-service-type @command{ganeti-mond} is an optional daemon that provides Ganeti monitoring functionality. It is responsible for running data collectors and publish the collected information through a HTTP interface. It takes a @code{ganeti-mond-configuration} object. @end defvr @deftp {Data Type} ganeti-mond-configuration @table @asis @item @code{ganeti} (default: @code{ganeti}) The @code{ganeti} package to use for this service. @item @code{port} (default: @code{1815}) The port on which the daemon will listen. @item @code{address} (default: @code{"0.0.0.0"}) The network address that the daemon will bind to. By default it binds to all available interfaces. @item @code{debug?} (default: @code{#f}) When true, the daemon performs additional logging for debugging purposes. @end table @end deftp @defvr {Scheme Variable} ganeti-metad-service-type @command{ganeti-metad} is an optional daemon that can be used to provide information about the cluster to instances or OS install scripts. It takes a @code{ganeti-metad-configuration} object. @end defvr @deftp {Data Type} ganeti-metad-configuration @table @asis @item @code{ganeti} (default: @code{ganeti}) The @code{ganeti} package to use for this service. @item @code{port} (default: @code{80}) The port on which the daemon will listen. @item @code{address} (default: @code{#f}) If set, the daemon will bind to this address only. If left unset, the behavior depends on the cluster configuration. @item @code{debug?} (default: @code{#f}) When true, the daemon performs additional logging for debugging purposes. @end table @end deftp @defvr {Scheme Variable} ganeti-watcher-service-type @command{ganeti-watcher} is a script designed to run periodically and ensure the health of a cluster. It will automatically restart instances that have stopped without Ganeti's consent, and repairs DRBD links in case a node has rebooted. It also archives old cluster jobs and restarts Ganeti daemons that are not running. If the cluster parameter @code{ensure_node_health} is set, the watcher will also shutdown instances and DRBD devices if the node it is running on is declared offline by known master candidates. It can be paused on all nodes with @command{gnt-cluster watcher pause}. The service takes a @code{ganeti-watcher-configuration} object. @end defvr @deftp {Data Type} ganeti-watcher-configuration @table @asis @item @code{ganeti} (default: @code{ganeti}) The @code{ganeti} package to use for this service. @item @code{schedule} (default: @code{'(next-second-from (next-minute (range 0 60 5)))}) How often to run the script. The default is every five minutes. @item @code{rapi-ip} (default: @code{#f}) This option needs to be specified only if the RAPI daemon is configured to use a particular interface or address. By default the cluster address is used. @item @code{job-age} (default: @code{(* 6 3600)}) Archive cluster jobs older than this age, specified in seconds. The default is 6 hours. This keeps @command{gnt-job list} manageable. @item @code{verify-disks?} (default: @code{#t}) If this is @code{#f}, the watcher will not try to repair broken DRBD links automatically. Administrators will need to use @command{gnt-cluster verify-disks} manually instead. @item @code{debug?} (default: @code{#f}) When @code{#t}, the script performs additional logging for debugging purposes. @end table @end deftp @defvr {Scheme Variable} ganeti-cleaner-service-type @command{ganeti-cleaner} is a script designed to run periodically and remove old files from the cluster. This service type controls two @dfn{cron jobs}: one intended for the master node that permanently purges old cluster jobs, and one intended for every node that removes expired X509 certificates, keys, and outdated @command{ganeti-watcher} information. Like all Ganeti services, it is safe to include even on non-master nodes as it will disable itself as necessary. It takes a @code{ganeti-cleaner-configuration} object. @end defvr @deftp {Data Type} ganeti-cleaner-configuration @table @asis @item @code{ganeti} (default: @code{ganeti}) The @code{ganeti} package to use for the @command{gnt-cleaner} command. @item @code{master-schedule} (default: @code{"45 1 * * *"}) How often to run the master cleaning job. The default is once per day, at 01:45:00. @item @code{node-schedule} (default: @code{"45 2 * * *"}) How often to run the node cleaning job. The default is once per day, at 02:45:00. @end table @end deftp @node Version Control Services @subsection Version Control Services The @code{(gnu services version-control)} module provides a service to allow remote access to local Git repositories. There are three options: the @code{git-daemon-service}, which provides access to repositories via the @code{git://} unsecured TCP-based protocol, extending the @code{nginx} web server to proxy some requests to @code{git-http-backend}, or providing a web interface with @code{cgit-service-type}. @deffn {Scheme Procedure} git-daemon-service [#:config (git-daemon-configuration)] Return a service that runs @command{git daemon}, a simple TCP server to expose repositories over the Git protocol for anonymous access. The optional @var{config} argument should be a @code{} object, by default it allows read-only access to exported@footnote{By creating the magic file @file{git-daemon-export-ok} in the repository directory.} repositories under @file{/srv/git}. @end deffn @deftp {Data Type} git-daemon-configuration Data type representing the configuration for @code{git-daemon-service}. @table @asis @item @code{package} (default: @code{git}) Package object of the Git distributed version control system. @item @code{export-all?} (default: @code{#f}) Whether to allow access for all Git repositories, even if they do not have the @file{git-daemon-export-ok} file. @item @code{base-path} (default: @file{/srv/git}) Whether to remap all the path requests as relative to the given path. If you run @command{git daemon} with @code{(base-path "/srv/git")} on @samp{example.com}, then if you later try to pull @indicateurl{git://example.com/hello.git}, git daemon will interpret the path as @file{/srv/git/hello.git}. @item @code{user-path} (default: @code{#f}) Whether to allow @code{~user} notation to be used in requests. When specified with empty string, requests to @indicateurl{git://host/~alice/foo} is taken as a request to access @code{foo} repository in the home directory of user @code{alice}. If @code{(user-path "@var{path}")} is specified, the same request is taken as a request to access @file{@var{path}/foo} repository in the home directory of user @code{alice}. @item @code{listen} (default: @code{'()}) Whether to listen on specific IP addresses or hostnames, defaults to all. @item @code{port} (default: @code{#f}) Whether to listen on an alternative port, which defaults to 9418. @item @code{whitelist} (default: @code{'()}) If not empty, only allow access to this list of directories. @item @code{extra-options} (default: @code{'()}) Extra options will be passed to @command{git daemon}, please run @command{man git-daemon} for more information. @end table @end deftp The @code{git://} protocol lacks authentication. When you pull from a repository fetched via @code{git://}, you don't know whether the data you receive was modified or is even coming from the specified host, and your connection is subject to eavesdropping. It's better to use an authenticated and encrypted transport, such as @code{https}. Although Git allows you to serve repositories using unsophisticated file-based web servers, there is a faster protocol implemented by the @code{git-http-backend} program. This program is the back-end of a proper Git web service. It is designed to sit behind a FastCGI proxy. @xref{Web Services}, for more on running the necessary @code{fcgiwrap} daemon. Guix has a separate configuration data type for serving Git repositories over HTTP. @deftp {Data Type} git-http-configuration Data type representing the configuration for a future @code{git-http-service-type}; can currently be used to configure Nginx through @code{git-http-nginx-location-configuration}. @table @asis @item @code{package} (default: @var{git}) Package object of the Git distributed version control system. @item @code{git-root} (default: @file{/srv/git}) Directory containing the Git repositories to expose to the world. @item @code{export-all?} (default: @code{#f}) Whether to expose access for all Git repositories in @var{git-root}, even if they do not have the @file{git-daemon-export-ok} file. @item @code{uri-path} (default: @samp{/git/}) Path prefix for Git access. With the default @samp{/git/} prefix, this will map @indicateurl{http://@var{server}/git/@var{repo}.git} to @file{/srv/git/@var{repo}.git}. Requests whose URI paths do not begin with this prefix are not passed on to this Git instance. @item @code{fcgiwrap-socket} (default: @code{127.0.0.1:9000}) The socket on which the @code{fcgiwrap} daemon is listening. @xref{Web Services}. @end table @end deftp There is no @code{git-http-service-type}, currently; instead you can create an @code{nginx-location-configuration} from a @code{git-http-configuration} and then add that location to a web server. @deffn {Scheme Procedure} git-http-nginx-location-configuration @ [config=(git-http-configuration)] Compute an @code{nginx-location-configuration} that corresponds to the given Git http configuration. An example nginx service definition to serve the default @file{/srv/git} over HTTPS might be: @lisp (service nginx-service-type (nginx-configuration (server-blocks (list (nginx-server-configuration (listen '("443 ssl")) (server-name "git.my-host.org") (ssl-certificate "/etc/letsencrypt/live/git.my-host.org/fullchain.pem") (ssl-certificate-key "/etc/letsencrypt/live/git.my-host.org/privkey.pem") (locations (list (git-http-nginx-location-configuration (git-http-configuration (uri-path "/")))))))))) @end lisp This example assumes that you are using Let's Encrypt to get your TLS certificate. @xref{Certificate Services}. The default @code{certbot} service will redirect all HTTP traffic on @code{git.my-host.org} to HTTPS. You will also need to add an @code{fcgiwrap} proxy to your system services. @xref{Web Services}. @end deffn @subsubheading Cgit Service @cindex Cgit service @cindex Git, web interface @uref{https://git.zx2c4.com/cgit/, Cgit} is a web frontend for Git repositories written in C. The following example will configure the service with default values. By default, Cgit can be accessed on port 80 (@code{http://localhost:80}). @lisp (service cgit-service-type) @end lisp The @code{file-object} type designates either a file-like object (@pxref{G-Expressions, file-like objects}) or a string. @c %start of fragment Available @code{cgit-configuration} fields are: @deftypevr {@code{cgit-configuration} parameter} package package The CGIT package. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} nginx-server-configuration-list nginx NGINX configuration. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} file-object about-filter Specifies a command which will be invoked to format the content of about pages (both top-level and for each repository). Defaults to @samp{""}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} string agefile Specifies a path, relative to each repository path, which can be used to specify the date and time of the youngest commit in the repository. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} file-object auth-filter Specifies a command that will be invoked for authenticating repository access. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} string branch-sort Flag which, when set to @samp{age}, enables date ordering in the branch ref list, and when set @samp{name} enables ordering by branch name. Defaults to @samp{"name"}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} string cache-root Path used to store the cgit cache entries. Defaults to @samp{"/var/cache/cgit"}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} integer cache-static-ttl Number which specifies the time-to-live, in minutes, for the cached version of repository pages accessed with a fixed SHA1. Defaults to @samp{-1}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} integer cache-dynamic-ttl Number which specifies the time-to-live, in minutes, for the cached version of repository pages accessed without a fixed SHA1. Defaults to @samp{5}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} integer cache-repo-ttl Number which specifies the time-to-live, in minutes, for the cached version of the repository summary page. Defaults to @samp{5}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} integer cache-root-ttl Number which specifies the time-to-live, in minutes, for the cached version of the repository index page. Defaults to @samp{5}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} integer cache-scanrc-ttl Number which specifies the time-to-live, in minutes, for the result of scanning a path for Git repositories. Defaults to @samp{15}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} integer cache-about-ttl Number which specifies the time-to-live, in minutes, for the cached version of the repository about page. Defaults to @samp{15}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} integer cache-snapshot-ttl Number which specifies the time-to-live, in minutes, for the cached version of snapshots. Defaults to @samp{5}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} integer cache-size The maximum number of entries in the cgit cache. When set to @samp{0}, caching is disabled. Defaults to @samp{0}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} boolean case-sensitive-sort? Sort items in the repo list case sensitively. Defaults to @samp{#t}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} list clone-prefix List of common prefixes which, when combined with a repository URL, generates valid clone URLs for the repository. Defaults to @samp{()}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} list clone-url List of @code{clone-url} templates. Defaults to @samp{()}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} file-object commit-filter Command which will be invoked to format commit messages. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} string commit-sort Flag which, when set to @samp{date}, enables strict date ordering in the commit log, and when set to @samp{topo} enables strict topological ordering. Defaults to @samp{"git log"}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} file-object css URL which specifies the css document to include in all cgit pages. Defaults to @samp{"/share/cgit/cgit.css"}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} file-object email-filter Specifies a command which will be invoked to format names and email address of committers, authors, and taggers, as represented in various places throughout the cgit interface. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} boolean embedded? Flag which, when set to @samp{#t}, will make cgit generate a HTML fragment suitable for embedding in other HTML pages. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} boolean enable-commit-graph? Flag which, when set to @samp{#t}, will make cgit print an ASCII-art commit history graph to the left of the commit messages in the repository log page. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} boolean enable-filter-overrides? Flag which, when set to @samp{#t}, allows all filter settings to be overridden in repository-specific cgitrc files. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} boolean enable-follow-links? Flag which, when set to @samp{#t}, allows users to follow a file in the log view. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} boolean enable-http-clone? If set to @samp{#t}, cgit will act as an dumb HTTP endpoint for Git clones. Defaults to @samp{#t}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} boolean enable-index-links? Flag which, when set to @samp{#t}, will make cgit generate extra links "summary", "commit", "tree" for each repo in the repository index. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} boolean enable-index-owner? Flag which, when set to @samp{#t}, will make cgit display the owner of each repo in the repository index. Defaults to @samp{#t}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} boolean enable-log-filecount? Flag which, when set to @samp{#t}, will make cgit print the number of modified files for each commit on the repository log page. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} boolean enable-log-linecount? Flag which, when set to @samp{#t}, will make cgit print the number of added and removed lines for each commit on the repository log page. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} boolean enable-remote-branches? Flag which, when set to @code{#t}, will make cgit display remote branches in the summary and refs views. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} boolean enable-subject-links? Flag which, when set to @code{1}, will make cgit use the subject of the parent commit as link text when generating links to parent commits in commit view. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} boolean enable-html-serving? Flag which, when set to @samp{#t}, will make cgit use the subject of the parent commit as link text when generating links to parent commits in commit view. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} boolean enable-tree-linenumbers? Flag which, when set to @samp{#t}, will make cgit generate linenumber links for plaintext blobs printed in the tree view. Defaults to @samp{#t}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} boolean enable-git-config? Flag which, when set to @samp{#f}, will allow cgit to use Git config to set any repo specific settings. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} file-object favicon URL used as link to a shortcut icon for cgit. Defaults to @samp{"/favicon.ico"}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} string footer The content of the file specified with this option will be included verbatim at the bottom of all pages (i.e.@: it replaces the standard "generated by..."@: message). Defaults to @samp{""}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} string head-include The content of the file specified with this option will be included verbatim in the HTML HEAD section on all pages. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} string header The content of the file specified with this option will be included verbatim at the top of all pages. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} file-object include Name of a configfile to include before the rest of the current config- file is parsed. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} string index-header The content of the file specified with this option will be included verbatim above the repository index. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} string index-info The content of the file specified with this option will be included verbatim below the heading on the repository index page. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} boolean local-time? Flag which, if set to @samp{#t}, makes cgit print commit and tag times in the servers timezone. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} file-object logo URL which specifies the source of an image which will be used as a logo on all cgit pages. Defaults to @samp{"/share/cgit/cgit.png"}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} string logo-link URL loaded when clicking on the cgit logo image. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} file-object owner-filter Command which will be invoked to format the Owner column of the main page. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} integer max-atom-items Number of items to display in atom feeds view. Defaults to @samp{10}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} integer max-commit-count Number of entries to list per page in "log" view. Defaults to @samp{50}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} integer max-message-length Number of commit message characters to display in "log" view. Defaults to @samp{80}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} integer max-repo-count Specifies the number of entries to list per page on the repository index page. Defaults to @samp{50}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} integer max-repodesc-length Specifies the maximum number of repo description characters to display on the repository index page. Defaults to @samp{80}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} integer max-blob-size Specifies the maximum size of a blob to display HTML for in KBytes. Defaults to @samp{0}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} string max-stats Maximum statistics period. Valid values are @samp{week},@samp{month}, @samp{quarter} and @samp{year}. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} mimetype-alist mimetype Mimetype for the specified filename extension. Defaults to @samp{((gif "image/gif") (html "text/html") (jpg "image/jpeg") (jpeg "image/jpeg") (pdf "application/pdf") (png "image/png") (svg "image/svg+xml"))}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} file-object mimetype-file Specifies the file to use for automatic mimetype lookup. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} string module-link Text which will be used as the formatstring for a hyperlink when a submodule is printed in a directory listing. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} boolean nocache? If set to the value @samp{#t} caching will be disabled. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} boolean noplainemail? If set to @samp{#t} showing full author email addresses will be disabled. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} boolean noheader? Flag which, when set to @samp{#t}, will make cgit omit the standard header on all pages. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} project-list project-list A list of subdirectories inside of @code{repository-directory}, relative to it, that should loaded as Git repositories. An empty list means that all subdirectories will be loaded. Defaults to @samp{()}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} file-object readme Text which will be used as default value for @code{cgit-repo-readme}. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} boolean remove-suffix? If set to @code{#t} and @code{repository-directory} is enabled, if any repositories are found with a suffix of @code{.git}, this suffix will be removed for the URL and name. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} integer renamelimit Maximum number of files to consider when detecting renames. Defaults to @samp{-1}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} string repository-sort The way in which repositories in each section are sorted. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} robots-list robots Text used as content for the @code{robots} meta-tag. Defaults to @samp{("noindex" "nofollow")}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} string root-desc Text printed below the heading on the repository index page. Defaults to @samp{"a fast webinterface for the git dscm"}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} string root-readme The content of the file specified with this option will be included verbatim below the ``about'' link on the repository index page. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} string root-title Text printed as heading on the repository index page. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} boolean scan-hidden-path If set to @samp{#t} and repository-directory is enabled, repository-directory will recurse into directories whose name starts with a period. Otherwise, repository-directory will stay away from such directories, considered as ``hidden''. Note that this does not apply to the @file{.git} directory in non-bare repos. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} list snapshots Text which specifies the default set of snapshot formats that cgit generates links for. Defaults to @samp{()}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} repository-directory repository-directory Name of the directory to scan for repositories (represents @code{scan-path}). Defaults to @samp{"/srv/git"}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} string section The name of the current repository section - all repositories defined after this option will inherit the current section name. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} string section-sort Flag which, when set to @samp{1}, will sort the sections on the repository listing by name. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} integer section-from-path A number which, if defined prior to repository-directory, specifies how many path elements from each repo path to use as a default section name. Defaults to @samp{0}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} boolean side-by-side-diffs? If set to @samp{#t} shows side-by-side diffs instead of unidiffs per default. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} file-object source-filter Specifies a command which will be invoked to format plaintext blobs in the tree view. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} integer summary-branches Specifies the number of branches to display in the repository ``summary'' view. Defaults to @samp{10}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} integer summary-log Specifies the number of log entries to display in the repository ``summary'' view. Defaults to @samp{10}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} integer summary-tags Specifies the number of tags to display in the repository ``summary'' view. Defaults to @samp{10}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} string strict-export Filename which, if specified, needs to be present within the repository for cgit to allow access to that repository. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} string virtual-root URL which, if specified, will be used as root for all cgit links. Defaults to @samp{"/"}. @end deftypevr @deftypevr {@code{cgit-configuration} parameter} repository-cgit-configuration-list repositories A list of @dfn{cgit-repo} records to use with config. Defaults to @samp{()}. Available @code{repository-cgit-configuration} fields are: @deftypevr {@code{repository-cgit-configuration} parameter} repo-list snapshots A mask of snapshot formats for this repo that cgit generates links for, restricted by the global @code{snapshots} setting. Defaults to @samp{()}. @end deftypevr @deftypevr {@code{repository-cgit-configuration} parameter} repo-file-object source-filter Override the default @code{source-filter}. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{repository-cgit-configuration} parameter} repo-string url The relative URL used to access the repository. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{repository-cgit-configuration} parameter} repo-file-object about-filter Override the default @code{about-filter}. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{repository-cgit-configuration} parameter} repo-string branch-sort Flag which, when set to @samp{age}, enables date ordering in the branch ref list, and when set to @samp{name} enables ordering by branch name. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{repository-cgit-configuration} parameter} repo-list clone-url A list of URLs which can be used to clone repo. Defaults to @samp{()}. @end deftypevr @deftypevr {@code{repository-cgit-configuration} parameter} repo-file-object commit-filter Override the default @code{commit-filter}. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{repository-cgit-configuration} parameter} repo-string commit-sort Flag which, when set to @samp{date}, enables strict date ordering in the commit log, and when set to @samp{topo} enables strict topological ordering. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{repository-cgit-configuration} parameter} repo-string defbranch The name of the default branch for this repository. If no such branch exists in the repository, the first branch name (when sorted) is used as default instead. By default branch pointed to by HEAD, or ``master'' if there is no suitable HEAD. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{repository-cgit-configuration} parameter} repo-string desc The value to show as repository description. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{repository-cgit-configuration} parameter} repo-string homepage The value to show as repository homepage. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{repository-cgit-configuration} parameter} repo-file-object email-filter Override the default @code{email-filter}. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{repository-cgit-configuration} parameter} maybe-repo-boolean enable-commit-graph? A flag which can be used to disable the global setting @code{enable-commit-graph?}. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{repository-cgit-configuration} parameter} maybe-repo-boolean enable-log-filecount? A flag which can be used to disable the global setting @code{enable-log-filecount?}. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{repository-cgit-configuration} parameter} maybe-repo-boolean enable-log-linecount? A flag which can be used to disable the global setting @code{enable-log-linecount?}. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{repository-cgit-configuration} parameter} maybe-repo-boolean enable-remote-branches? Flag which, when set to @code{#t}, will make cgit display remote branches in the summary and refs views. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{repository-cgit-configuration} parameter} maybe-repo-boolean enable-subject-links? A flag which can be used to override the global setting @code{enable-subject-links?}. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{repository-cgit-configuration} parameter} maybe-repo-boolean enable-html-serving? A flag which can be used to override the global setting @code{enable-html-serving?}. Defaults to @samp{disabled}. @end deftypevr @deftypevr {@code{repository-cgit-configuration} parameter} repo-boolean hide? Flag which, when set to @code{#t}, hides the repository from the repository index. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{repository-cgit-configuration} parameter} repo-boolean ignore? Flag which, when set to @samp{#t}, ignores the repository. Defaults to @samp{#f}. @end deftypevr @deftypevr {@code{repository-cgit-configuration} parameter} repo-file-object logo URL which specifies the source of an image which will be used as a logo on this repo’s pages. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{repository-cgit-configuration} parameter} repo-string logo-link URL loaded when clicking on the cgit logo image. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{repository-cgit-configuration} parameter} repo-file-object owner-filter Override the default @code{owner-filter}. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{repository-cgit-configuration} parameter} repo-string module-link Text which will be used as the formatstring for a hyperlink when a submodule is printed in a directory listing. The arguments for the formatstring are the path and SHA1 of the submodule commit. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{repository-cgit-configuration} parameter} module-link-path module-link-path Text which will be used as the formatstring for a hyperlink when a submodule with the specified subdirectory path is printed in a directory listing. Defaults to @samp{()}. @end deftypevr @deftypevr {@code{repository-cgit-configuration} parameter} repo-string max-stats Override the default maximum statistics period. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{repository-cgit-configuration} parameter} repo-string name The value to show as repository name. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{repository-cgit-configuration} parameter} repo-string owner A value used to identify the owner of the repository. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{repository-cgit-configuration} parameter} repo-string path An absolute path to the repository directory. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{repository-cgit-configuration} parameter} repo-string readme A path (relative to repo) which specifies a file to include verbatim as the ``About'' page for this repo. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{repository-cgit-configuration} parameter} repo-string section The name of the current repository section - all repositories defined after this option will inherit the current section name. Defaults to @samp{""}. @end deftypevr @deftypevr {@code{repository-cgit-configuration} parameter} repo-list extra-options Extra options will be appended to cgitrc file. Defaults to @samp{()}. @end deftypevr @end deftypevr @deftypevr {@code{cgit-configuration} parameter} list extra-options Extra options will be appended to cgitrc file. Defaults to @samp{()}. @end deftypevr @c %end of fragment However, it could be that you just want to get a @code{cgitrc} up and running. In that case, you can pass an @code{opaque-cgit-configuration} as a record to @code{cgit-service-type}. As its name indicates, an opaque configuration does not have easy reflective capabilities. Available @code{opaque-cgit-configuration} fields are: @deftypevr {@code{opaque-cgit-configuration} parameter} package cgit The cgit package. @end deftypevr @deftypevr {@code{opaque-cgit-configuration} parameter} string string The contents of the @code{cgitrc}, as a string. @end deftypevr For example, if your @code{cgitrc} is just the empty string, you could instantiate a cgit service like this: @lisp (service cgit-service-type (opaque-cgit-configuration (cgitrc ""))) @end lisp @subsubheading Gitolite Service @cindex Gitolite service @cindex Git, hosting @uref{https://gitolite.com/gitolite/, Gitolite} is a tool for hosting Git repositories on a central server. Gitolite can handle multiple repositories and users, and supports flexible configuration of the permissions for the users on the repositories. The following example will configure Gitolite using the default @code{git} user, and the provided SSH public key. @lisp (service gitolite-service-type (gitolite-configuration (admin-pubkey (plain-file "yourname.pub" "ssh-rsa AAAA... guix@@example.com")))) @end lisp Gitolite is configured through a special admin repository which you can clone, for example, if you setup Gitolite on @code{example.com}, you would run the following command to clone the admin repository. @example git clone git@@example.com:gitolite-admin @end example When the Gitolite service is activated, the provided @code{admin-pubkey} will be inserted in to the @file{keydir} directory in the gitolite-admin repository. If this results in a change in the repository, it will be committed using the message ``gitolite setup by GNU Guix''. @deftp {Data Type} gitolite-configuration Data type representing the configuration for @code{gitolite-service-type}. @table @asis @item @code{package} (default: @var{gitolite}) Gitolite package to use. @item @code{user} (default: @var{git}) User to use for Gitolite. This will be user that you use when accessing Gitolite over SSH. @item @code{group} (default: @var{git}) Group to use for Gitolite. @item @code{home-directory} (default: @var{"/var/lib/gitolite"}) Directory in which to store the Gitolite configuration and repositories. @item @code{rc-file} (default: @var{(gitolite-rc-file)}) A ``file-like'' object (@pxref{G-Expressions, file-like objects}), representing the configuration for Gitolite. @item @code{admin-pubkey} (default: @var{#f}) A ``file-like'' object (@pxref{G-Expressions, file-like objects}) used to setup Gitolite. This will be inserted in to the @file{keydir} directory within the gitolite-admin repository. To specify the SSH key as a string, use the @code{plain-file} function. @lisp (plain-file "yourname.pub" "ssh-rsa AAAA... guix@@example.com") @end lisp @end table @end deftp @deftp {Data Type} gitolite-rc-file Data type representing the Gitolite RC file. @table @asis @item @code{umask} (default: @code{#o0077}) This controls the permissions Gitolite sets on the repositories and their contents. A value like @code{#o0027} will give read access to the group used by Gitolite (by default: @code{git}). This is necessary when using Gitolite with software like cgit or gitweb. @item @code{git-config-keys} (default: @code{""}) Gitolite allows you to set git config values using the @samp{config} keyword. This setting allows control over the config keys to accept. @item @code{roles} (default: @code{'(("READERS" . 1) ("WRITERS" . ))}) Set the role names allowed to be used by users running the perms command. @item @code{enable} (default: @code{'("help" "desc" "info" "perms" "writable" "ssh-authkeys" "git-config" "daemon" "gitweb")}) This setting controls the commands and features to enable within Gitolite. @end table @end deftp @node Game Services @subsection Game Services @subsubheading The Battle for Wesnoth Service @cindex wesnothd @uref{https://wesnoth.org, The Battle for Wesnoth} is a fantasy, turn based tactical strategy game, with several single player campaigns, and multiplayer games (both networked and local). @defvar {Scheme Variable} wesnothd-service-type Service type for the wesnothd service. Its value must be a @code{wesnothd-configuration} object. To run wesnothd in the default configuration, instantiate it as: @lisp (service wesnothd-service-type) @end lisp @end defvar @deftp {Data Type} wesnothd-configuration Data type representing the configuration of @command{wesnothd}. @table @asis @item @code{package} (default: @code{wesnoth-server}) The wesnoth server package to use. @item @code{port} (default: @code{15000}) The port to bind the server to. @end table @end deftp @node PAM Mount Service @subsection PAM Mount Service @cindex pam-mount The @code{(gnu services pam-mount)} module provides a service allowing users to mount volumes when they log in. It should be able to mount any volume format supported by the system. @defvar {Scheme Variable} pam-mount-service-type Service type for PAM Mount support. @end defvar @deftp {Data Type} pam-mount-configuration Data type representing the configuration of PAM Mount. It takes the following parameters: @table @asis @item @code{rules} The configuration rules that will be used to generate @file{/etc/security/pam_mount.conf.xml}. The configuration rules are SXML elements (@pxref{SXML,,, guile, GNU Guile Reference Manual}), and the default ones don't mount anything for anyone at login: @lisp `((debug (@@ (enable "0"))) (mntoptions (@@ (allow ,(string-join '("nosuid" "nodev" "loop" "encryption" "fsck" "nonempty" "allow_root" "allow_other") ",")))) (mntoptions (@@ (require "nosuid,nodev"))) (logout (@@ (wait "0") (hup "0") (term "no") (kill "no"))) (mkmountpoint (@@ (enable "1") (remove "true")))) @end lisp Some @code{volume} elements must be added to automatically mount volumes at login. Here's an example allowing the user @code{alice} to mount her encrypted @env{HOME} directory and allowing the user @code{bob} to mount the partition where he stores his data: @lisp (define pam-mount-rules `((debug (@@ (enable "0"))) (volume (@@ (user "alice") (fstype "crypt") (path "/dev/sda2") (mountpoint "/home/alice"))) (volume (@@ (user "bob") (fstype "auto") (path "/dev/sdb3") (mountpoint "/home/bob/data") (options "defaults,autodefrag,compress"))) (mntoptions (@@ (allow ,(string-join '("nosuid" "nodev" "loop" "encryption" "fsck" "nonempty" "allow_root" "allow_other") ",")))) (mntoptions (@@ (require "nosuid,nodev"))) (logout (@@ (wait "0") (hup "0") (term "no") (kill "no"))) (mkmountpoint (@@ (enable "1") (remove "true"))))) (service pam-mount-service-type (pam-mount-configuration (rules pam-mount-rules))) @end lisp The complete list of possible options can be found in the man page for @uref{http://pam-mount.sourceforge.net/pam_mount.conf.5.html, pam_mount.conf}. @end table @end deftp @node Guix Services @subsection Guix Services @subsubheading Guix Build Coordinator The @uref{https://git.cbaines.net/guix/build-coordinator/,Guix Build Coordinator} aids in distributing derivation builds among machines running an @dfn{agent}. The build daemon is still used to build the derivations, but the Guix Build Coordinator manages allocating builds and working with the results. @quotation Note This service is considered experimental. Configuration options may be changed in a backwards-incompatible manner, and not all features have been thorougly tested. @end quotation The Guix Build Coordinator consists of one @dfn{coordinator}, and one or more connected @dfn{agent} processes. The coordinator process handles clients submitting builds, and allocating builds to agents. The agent processes talk to a build daemon to actually perform the builds, then send the results back to the coordinator. There is a script to run the coordinator component of the Guix Build Coordinator, but the Guix service uses a custom Guile script instead, to provide better integration with G-expressions used in the configuration. @defvar {Scheme Variable} guix-build-coordinator-service-type Service type for the Guix Build Coordinator. Its value must be a @code{guix-build-coordinator-configuration} object. @end defvar @deftp {Data Type} guix-build-coordinator-configuration Data type representing the configuration of the Guix Build Coordinator. @table @asis @item @code{package} (default: @code{guix-build-coordinator}) The Guix Build Coordinator package to use. @item @code{user} (default: @code{"guix-build-coordinator"}) The system user to run the service as. @item @code{group} (default: @code{"guix-build-coordinator"}) The system group to run the service as. @item @code{database-uri-string} (default: @code{"sqlite:///var/lib/guix-build-coordinator/guix_build_coordinator.db"}) The URI to use for the database. @item @code{agent-communication-uri} (default: @code{"http://0.0.0.0:8745"}) The URI describing how to listen to requests from agent processes. @item @code{client-communication-uri} (default: @code{"http://127.0.0.1:8746"}) The URI describing how to listen to requests from clients. The client API allows submitting builds and currently isn't authenticated, so take care when configuring this value. @item @code{allocation-strategy} (default: @code{#~basic-build-allocation-strategy}) A G-expression for the allocation strategy to be used. This is a procedure that takes the datastore as an argument and populates the allocation plan in the database. @item @code{hooks} (default: @var{'()}) An association list of hooks. These provide a way to execute arbitrary code upon certain events, like a build result being processed. @item @code{guile} (default: @code{guile-3.0-latest}) The Guile package with which to run the Guix Build Coordinator. @end table @end deftp @defvar {Scheme Variable} guix-build-coordinator-agent-service-type Service type for a Guix Build Coordinator agent. Its value must be a @code{guix-build-coordinator-agent-configuration} object. @end defvar @deftp {Data Type} guix-build-coordinator-agent-configuration Data type representing the configuration a Guix Build Coordinator agent. @table @asis @item @code{package} (default: @code{guix-build-coordinator}) The Guix Build Coordinator package to use. @item @code{user} (default: @code{"guix-build-coordinator-agent"}) The system user to run the service as. @item @code{coordinator} (default: @code{"http://localhost:8745"}) The URI to use when connecting to the coordinator. @item @code{uuid} The UUID of the agent. This should be generated by the coordinator process, stored in the coordinator database, and used by the intended agent. @item @code{password} (default: @code{#f}) The password to use when connecting to the coordinator. A file to read the password from can also be specified, and this is more secure. @item @code{password-file} (default: @code{#f}) A file containing the password to use when connecting to the coordinator. @item @code{systems} (default: @code{#f}) The systems for which this agent should fetch builds. The agent process will use the current system it's running on as the default. @item @code{max-parallel-builds} (default: @code{1}) The number of builds to perform in parallel. @item @code{derivation-substitute-urls} (default: @code{#f}) URLs from which to attempt to fetch substitutes for derivations, if the derivations aren't already available. @item @code{non-derivation-substitute-urls} (default: @code{#f}) URLs from which to attempt to fetch substitutes for build inputs, if the input store items aren't already available. @end table @end deftp The Guix Build Coordinator package contains a script to query an instance of the Guix Data Service for derivations to build, and then submit builds for those derivations to the coordinator. The service type below assists in running this script. This is an additional tool that may be useful when building derivations contained within an instance of the Guix Data Service. @defvar {Scheme Variable} guix-build-coordinator-queue-builds-service-type Service type for the guix-build-coordinator-queue-builds-from-guix-data-service script. Its value must be a @code{guix-build-coordinator-queue-builds-configuration} object. @end defvar @deftp {Data Type} guix-build-coordinator-queue-builds-configuration Data type representing the options to the queue builds from guix data service script. @table @asis @item @code{package} (default: @code{guix-build-coordinator}) The Guix Build Coordinator package to use. @item @code{user} (default: @code{"guix-build-coordinator-queue-builds"}) The system user to run the service as. @item @code{coordinator} (default: @code{"http://localhost:8745"}) The URI to use when connecting to the coordinator. @item @code{systems} (default: @code{#f}) The systems for which to fetch derivations to build. @item @code{systems-and-targets} (default: @code{#f}) An association list of system and target pairs for which to fetch derivations to build. @item @code{guix-data-service} (default: @code{"https://data.guix.gnu.org"}) The Guix Data Service instance from which to query to find out about derivations to build. @item @code{processed-commits-file} (default: @code{"/var/cache/guix-build-coordinator-queue-builds/processed-commits"}) A file to record which commits have been processed, to avoid needlessly processing them again if the service is restarted. @end table @end deftp @subsubheading Guix Data Service The @uref{http://data.guix.gnu.org,Guix Data Service} processes, stores and provides data about GNU Guix. This includes information about packages, derivations and lint warnings. The data is stored in a PostgreSQL database, and available through a web interface. @defvar {Scheme Variable} guix-data-service-type Service type for the Guix Data Service. Its value must be a @code{guix-data-service-configuration} object. The service optionally extends the getmail service, as the guix-commits mailing list is used to find out about changes in the Guix git repository. @end defvar @deftp {Data Type} guix-data-service-configuration Data type representing the configuration of the Guix Data Service. @table @asis @item @code{package} (default: @code{guix-data-service}) The Guix Data Service package to use. @item @code{user} (default: @code{"guix-data-service"}) The system user to run the service as. @item @code{group} (default: @code{"guix-data-service"}) The system group to run the service as. @item @code{port} (default: @code{8765}) The port to bind the web service to. @item @code{host} (default: @code{"127.0.0.1"}) The host to bind the web service to. @item @code{getmail-idle-mailboxes} (default: @code{#f}) If set, this is the list of mailboxes that the getmail service will be configured to listen to. @item @code{commits-getmail-retriever-configuration} (default: @code{#f}) If set, this is the @code{getmail-retriever-configuration} object with which to configure getmail to fetch mail from the guix-commits mailing list. @item @code{extra-options} (default: @var{'()}) Extra command line options for @code{guix-data-service}. @item @code{extra-process-jobs-options} (default: @var{'()}) Extra command line options for @code{guix-data-service-process-jobs}. @end table @end deftp @node Linux Services @subsection Linux Services @cindex oom @cindex out of memory killer @cindex earlyoom @cindex early out of memory daemon @subsubheading Early OOM Service @uref{https://github.com/rfjakob/earlyoom,Early OOM}, also known as Earlyoom, is a minimalist out of memory (OOM) daemon that runs in user space and provides a more responsive and configurable alternative to the in-kernel OOM killer. It is useful to prevent the system from becoming unresponsive when it runs out of memory. @deffn {Scheme Variable} earlyoom-service-type The service type for running @command{earlyoom}, the Early OOM daemon. Its value must be a @code{earlyoom-configuration} object, described below. The service can be instantiated in its default configuration with: @lisp (service earlyoom-service-type) @end lisp @end deffn @deftp {Data Type} earlyoom-configuration This is the configuration record for the @code{earlyoom-service-type}. @table @asis @item @code{earlyoom} (default: @var{earlyoom}) The Earlyoom package to use. @item @code{minimum-available-memory} (default: @code{10}) The threshold for the minimum @emph{available} memory, in percentages. @item @code{minimum-free-swap} (default: @code{10}) The threshold for the minimum free swap memory, in percentages. @item @code{prefer-regexp} (default: @code{#f}) A regular expression (as a string) to match the names of the processes that should be preferably killed. @item @code{avoid-regexp} (default: @code{#f}) A regular expression (as a string) to match the names of the processes that should @emph{not} be killed. @item @code{memory-report-interval} (default: @code{0}) The interval in seconds at which a memory report is printed. It is disabled by default. @item @code{ignore-positive-oom-score-adj?} (default: @code{#f}) A boolean indicating whether the positive adjustments set in @file{/proc/*/oom_score_adj} should be ignored. @item @code{show-debug-messages?} (default: @code{#f}) A boolean indicating whether debug messages should be printed. The logs are saved at @file{/var/log/earlyoom.log}. @item @code{send-notification-command} (default: @code{#f}) This can be used to provide a custom command used for sending notifications. @end table @end deftp @cindex modprobe @cindex kernel module loader @subsubheading Kernel Module Loader Service The kernel module loader service allows one to load loadable kernel modules at boot. This is especially useful for modules that don't autoload and need to be manually loaded, as it's the case with @code{ddcci}. @deffn {Scheme Variable} kernel-module-loader-service-type The service type for loading loadable kernel modules at boot with @command{modprobe}. Its value must be a list of strings representing module names. For example loading the drivers provided by @code{ddcci-driver-linux}, in debugging mode by passing some module parameters, can be done as follow: @lisp (use-modules (gnu) (gnu services)) (use-package-modules linux) (use-service-modules linux) (define ddcci-config (plain-file "ddcci.conf" "options ddcci dyndbg delay=120")) (operating-system ... (services (cons* (service kernel-module-loader-service-type '("ddcci" "ddcci_backlight")) (simple-service 'ddcci-config etc-service-type (list `("modprobe.d/ddcci.conf" ,ddcci-config))) %base-services)) (kernel-loadable-modules (list ddcci-driver-linux))) @end lisp @end deffn @cindex zram @cindex compressed swap @cindex Compressed RAM-based block devices @subsubheading Zram Device Service The Zram device service provides a compressed swap device in system memory. The Linux Kernel documentation has more information about @uref{https://www.kernel.org/doc/html/latest/admin-guide/blockdev/zram.html,zram} devices. @deffn {Scheme Variable} zram-device-service-type This service creates the zram block device, formats it as swap and enables it as a swap device. The service's value is a @code{zram-device-configuration} record. @deftp {Data Type} zram-device-configuration This is the data type representing the configuration for the zram-device service. @table @asis @item @code{size} (default @code{"1G"}) This is the amount of space you wish to provide for the zram device. It accepts a string and can be a number of bytes or use a suffix, eg.: @code{"512M"} or @code{1024000}. @item @code{compression-algorithm} (default @code{'lzo}) This is the compression algorithm you wish to use. It is difficult to list all the possible compression options, but common ones supported by Guix's Linux Libre Kernel include @code{'lzo}, @code{'lz4} and @code{'zstd}. @item @code{memory-limit} (default @code{0}) This is the maximum amount of memory which the zram device can use. Setting it to '0' disables the limit. While it is generally expected that compression will be 2:1, it is possible that uncompressable data can be written to swap and this is a method to limit how much memory can be used. It accepts a string and can be a number of bytes or use a suffix, eg.: @code{"2G"}. @item @code{priority} (default @code{-1}) This is the priority of the swap device created from the zram device. @code{swapon} accepts values between -1 and 32767, with higher values indicating higher priority. Higher priority swap will generally be used first. @end table @end deftp @end deffn @node Hurd Services @subsection Hurd Services @defvr {Scheme Variable} hurd-console-service-type This service starts the fancy @code{VGA} console client on the Hurd. The service's value is a @code{hurd-console-configuration} record. @end defvr @deftp {Data Type} hurd-console-configuration This is the data type representing the configuration for the hurd-console-service. @table @asis @item @code{hurd} (default: @var{hurd}) The Hurd package to use. @end table @end deftp @defvr {Scheme Variable} hurd-getty-service-type This service starts a tty using the Hurd @code{getty} program. The service's value is a @code{hurd-getty-configuration} record. @end defvr @deftp {Data Type} hurd-getty-configuration This is the data type representing the configuration for the hurd-getty-service. @table @asis @item @code{hurd} (default: @var{hurd}) The Hurd package to use. @item @code{tty} The name of the console this Getty runs on---e.g., @code{"tty1"}. @item @code{baud-rate} (default: @code{38400}) An integer specifying the baud rate of the tty. @end table @end deftp @node Miscellaneous Services @subsection Miscellaneous Services @cindex fingerprint @subsubheading Fingerprint Service The @code{(gnu services authentication)} module provides a DBus service to read and identify fingerprints via a fingerprint sensor. @defvr {Scheme Variable} fprintd-service-type The service type for @command{fprintd}, which provides the fingerprint reading capability. @lisp (service fprintd-service-type) @end lisp @end defvr @cindex sysctl @subsubheading System Control Service The @code{(gnu services sysctl)} provides a service to configure kernel parameters at boot. @defvr {Scheme Variable} sysctl-service-type The service type for @command{sysctl}, which modifies kernel parameters under @file{/proc/sys/}. To enable IPv4 forwarding, it can be instantiated as: @lisp (service sysctl-service-type (sysctl-configuration (settings '(("net.ipv4.ip_forward" . "1"))))) @end lisp @end defvr @deftp {Data Type} sysctl-configuration The data type representing the configuration of @command{sysctl}. @table @asis @item @code{sysctl} (default: @code{(file-append procps "/sbin/sysctl"}) The @command{sysctl} executable to use. @item @code{settings} (default: @code{'()}) An association list specifies kernel parameters and their values. @end table @end deftp @cindex pcscd @subsubheading PC/SC Smart Card Daemon Service The @code{(gnu services security-token)} module provides the following service to run @command{pcscd}, the PC/SC Smart Card Daemon. @command{pcscd} is the daemon program for pcsc-lite and the MuscleCard framework. It is a resource manager that coordinates communications with smart card readers, smart cards and cryptographic tokens that are connected to the system. @defvr {Scheme Variable} pcscd-service-type Service type for the @command{pcscd} service. Its value must be a @code{pcscd-configuration} object. To run pcscd in the default configuration, instantiate it as: @lisp (service pcscd-service-type) @end lisp @end defvr @deftp {Data Type} pcscd-configuration The data type representing the configuration of @command{pcscd}. @table @asis @item @code{pcsc-lite} (default: @code{pcsc-lite}) The pcsc-lite package that provides pcscd. @item @code{usb-drivers} (default: @code{(list ccid)}) List of packages that provide USB drivers to pcscd. Drivers are expected to be under @file{pcsc/drivers} in the store directory of the package. @end table @end deftp @cindex lirc @subsubheading Lirc Service The @code{(gnu services lirc)} module provides the following service. @deffn {Scheme Procedure} lirc-service [#:lirc lirc] @ [#:device #f] [#:driver #f] [#:config-file #f] @ [#:extra-options '()] Return a service that runs @url{http://www.lirc.org,LIRC}, a daemon that decodes infrared signals from remote controls. Optionally, @var{device}, @var{driver} and @var{config-file} (configuration file name) may be specified. See @command{lircd} manual for details. Finally, @var{extra-options} is a list of additional command-line options passed to @command{lircd}. @end deffn @cindex spice @subsubheading Spice Service The @code{(gnu services spice)} module provides the following service. @deffn {Scheme Procedure} spice-vdagent-service [#:spice-vdagent] Returns a service that runs @url{https://www.spice-space.org,VDAGENT}, a daemon that enables sharing the clipboard with a vm and setting the guest display resolution when the graphical console window resizes. @end deffn @cindex inputattach @subsubheading inputattach Service @cindex tablet input, for Xorg @cindex touchscreen input, for Xorg The @uref{https://linuxwacom.github.io/, inputattach} service allows you to use input devices such as Wacom tablets, touchscreens, or joysticks with the Xorg display server. @deffn {Scheme Variable} inputattach-service-type Type of a service that runs @command{inputattach} on a device and dispatches events from it. @end deffn @deftp {Data Type} inputattach-configuration @table @asis @item @code{device-type} (default: @code{"wacom"}) The type of device to connect to. Run @command{inputattach --help}, from the @code{inputattach} package, to see the list of supported device types. @item @code{device} (default: @code{"/dev/ttyS0"}) The device file to connect to the device. @item @code{baud-rate} (default: @code{#f}) Baud rate to use for the serial connection. Should be a number or @code{#f}. @item @code{log-file} (default: @code{#f}) If true, this must be the name of a file to log messages to. @end table @end deftp @subsubheading Dictionary Service @cindex dictionary The @code{(gnu services dict)} module provides the following service: @defvr {Scheme Variable} dicod-service-type This is the type of the service that runs the @command{dicod} daemon, an implementation of DICT server (@pxref{Dicod,,, dico, GNU Dico Manual}). @end defvr @deffn {Scheme Procedure} dicod-service [#:config (dicod-configuration)] Return a service that runs the @command{dicod} daemon, an implementation of DICT server (@pxref{Dicod,,, dico, GNU Dico Manual}). The optional @var{config} argument specifies the configuration for @command{dicod}, which should be a @code{} object, by default it serves the GNU Collaborative International Dictionary of English. You can add @command{open localhost} to your @file{~/.dico} file to make @code{localhost} the default server for @command{dico} client (@pxref{Initialization File,,, dico, GNU Dico Manual}). @end deffn @deftp {Data Type} dicod-configuration Data type representing the configuration of dicod. @table @asis @item @code{dico} (default: @var{dico}) Package object of the GNU Dico dictionary server. @item @code{interfaces} (default: @var{'("localhost")}) This is the list of IP addresses and ports and possibly socket file names to listen to (@pxref{Server Settings, @code{listen} directive,, dico, GNU Dico Manual}). @item @code{handlers} (default: @var{'()}) List of @code{} objects denoting handlers (module instances). @item @code{databases} (default: @var{(list %dicod-database:gcide)}) List of @code{} objects denoting dictionaries to be served. @end table @end deftp @deftp {Data Type} dicod-handler Data type representing a dictionary handler (module instance). @table @asis @item @code{name} Name of the handler (module instance). @item @code{module} (default: @var{#f}) Name of the dicod module of the handler (instance). If it is @code{#f}, the module has the same name as the handler. (@pxref{Modules,,, dico, GNU Dico Manual}). @item @code{options} List of strings or gexps representing the arguments for the module handler @end table @end deftp @deftp {Data Type} dicod-database Data type representing a dictionary database. @table @asis @item @code{name} Name of the database, will be used in DICT commands. @item @code{handler} Name of the dicod handler (module instance) used by this database (@pxref{Handlers,,, dico, GNU Dico Manual}). @item @code{complex?} (default: @var{#f}) Whether the database configuration complex. The complex configuration will need a corresponding @code{} object, otherwise not. @item @code{options} List of strings or gexps representing the arguments for the database (@pxref{Databases,,, dico, GNU Dico Manual}). @end table @end deftp @defvr {Scheme Variable} %dicod-database:gcide A @code{} object serving the GNU Collaborative International Dictionary of English using the @code{gcide} package. @end defvr The following is an example @code{dicod-service} configuration. @lisp (dicod-service #:config (dicod-configuration (handlers (list (dicod-handler (name "wordnet") (module "dictorg") (options (list #~(string-append "dbdir=" #$wordnet)))))) (databases (list (dicod-database (name "wordnet") (complex? #t) (handler "wordnet") (options '("database=wn"))) %dicod-database:gcide)))) @end lisp @cindex Docker @subsubheading Docker Service The @code{(gnu services docker)} module provides the following services. @defvr {Scheme Variable} docker-service-type This is the type of the service that runs @url{https://www.docker.com,Docker}, a daemon that can execute application bundles (sometimes referred to as ``containers'') in isolated environments. @end defvr @deftp {Data Type} docker-configuration This is the data type representing the configuration of Docker and Containerd. @table @asis @item @code{package} (default: @code{docker}) The Docker daemon package to use. @item @code{package} (default: @code{docker-cli}) The Docker client package to use. @item @code{containerd} (default: @var{containerd}) The Containerd package to use. @item @code{proxy} (default @var{docker-libnetwork-cmd-proxy}) The Docker user-land networking proxy package to use. @item @code{enable-proxy?} (default @code{#t}) Enable or disable the use of the Docker user-land networking proxy. @item @code{debug?} (default @code{#f}) Enable or disable debug output. @item @code{enable-iptables?} (default @code{#t}) Enable or disable the addition of iptables rules. @end table @end deftp @cindex Singularity, container service @defvr {Scheme Variable} singularity-service-type This is the type of the service that allows you to run @url{https://www.sylabs.io/singularity/, Singularity}, a Docker-style tool to create and run application bundles (aka. ``containers''). The value for this service is the Singularity package to use. The service does not install a daemon; instead, it installs helper programs as setuid-root (@pxref{Setuid Programs}) such that unprivileged users can invoke @command{singularity run} and similar commands. @end defvr @cindex Audit @subsubheading Auditd Service The @code{(gnu services auditd)} module provides the following service. @defvr {Scheme Variable} auditd-service-type This is the type of the service that runs @url{https://people.redhat.com/sgrubb/audit/,auditd}, a daemon that tracks security-relevant information on your system. Examples of things that can be tracked: @enumerate @item File accesses @item System calls @item Invoked commands @item Failed login attempts @item Firewall filtering @item Network access @end enumerate @command{auditctl} from the @code{audit} package can be used in order to add or remove events to be tracked (until the next reboot). In order to permanently track events, put the command line arguments of auditctl into a file called @code{audit.rules} in the configuration directory (see below). @command{aureport} from the @code{audit} package can be used in order to view a report of all recorded events. The audit daemon by default logs into the file @file{/var/log/audit.log}. @end defvr @deftp {Data Type} auditd-configuration This is the data type representing the configuration of auditd. @table @asis @item @code{audit} (default: @code{audit}) The audit package to use. @item @code{configuration-directory} (default: @code{%default-auditd-configuration-directory}) The directory containing the configuration file for the audit package, which must be named @code{auditd.conf}, and optionally some audit rules to instantiate on startup. @end table @end deftp @cindex rshiny @subsubheading R-Shiny service The @code{(gnu services science)} module provides the following service. @defvr {Scheme Variable} rshiny-service-type This is a type of service which is used to run a webapp created with @code{r-shiny}. This service sets the @env{R_LIBS_USER} environment variable and runs the provided script to call @code{runApp}. @deftp {Data Type} rshiny-configuration This is the data type representing the configuration of rshiny. @table @asis @item @code{package} (default: @code{r-shiny}) The package to use. @item @code{binary} (defaunlt @code{"rshiny"}) The name of the binary or shell script located at @code{package/bin/} to run when the service is run. The common way to create this file is as follows: @lisp @dots{} (let* ((out (assoc-ref %outputs "out")) (targetdir (string-append out "/share/" ,name)) (app (string-append out "/bin/" ,name)) (Rbin (string-append (assoc-ref %build-inputs "r-min") "/bin/Rscript"))) ;; @dots{} (mkdir-p (string-append out "/bin")) (call-with-output-file app (lambda (port) (format port "#!~a library(shiny) setwd(\"~a\") runApp(launch.browser=0, port=4202)~%\n" Rbin targetdir)))) @end lisp @end table @end deftp @end defvr @cindex Nix @subsubheading Nix service The @code{(gnu services nix)} module provides the following service. @defvr {Scheme Variable} nix-service-type This is the type of the service that runs build daemon of the @url{https://nixos.org/nix/, Nix} package manager. Here is an example showing how to use it: @lisp (use-modules (gnu)) (use-service-modules nix) (use-package-modules package-management) (operating-system ;; @dots{} (packages (append (list nix) %base-packages)) (services (append (list (service nix-service-type)) %base-services))) @end lisp After @command{guix system reconfigure} configure Nix for your user: @itemize @item Add a Nix channel and update it. See @url{https://nixos.org/nix/manual/, Nix Package Manager Guide}. @item Create a symlink to your profile and activate Nix profile: @end itemize @example $ ln -s "/nix/var/nix/profiles/per-user/$USER/profile" ~/.nix-profile $ source /run/current-system/profile/etc/profile.d/nix.sh @end example @end defvr @deftp {Data Type} nix-configuration This data type represents the configuration of the Nix daemon. @table @asis @item @code{nix} (default: @code{nix}) The Nix package to use. @item @code{sandbox} (default: @code{#t}) Specifies whether builds are sandboxed by default. @item @code{build-sandbox-items} (default: @code{'()}) This is a list of strings or objects appended to the @code{build-sandbox-items} field of the configuration file. @item @code{extra-config} (default: @code{'()}) This is a list of strings or objects appended to the configuration file. It is used to pass extra text to be added verbatim to the configuration file. @item @code{extra-options} (default: @code{'()}) Extra command line options for @code{nix-service-type}. @end table @end deftp @node Setuid Programs @section Setuid Programs @cindex setuid programs Some programs need to run with ``root'' privileges, even when they are launched by unprivileged users. A notorious example is the @command{passwd} program, which users can run to change their password, and which needs to access the @file{/etc/passwd} and @file{/etc/shadow} files---something normally restricted to root, for obvious security reasons. To address that, these executables are @dfn{setuid-root}, meaning that they always run with root privileges (@pxref{How Change Persona,,, libc, The GNU C Library Reference Manual}, for more info about the setuid mechanism). The store itself @emph{cannot} contain setuid programs: that would be a security issue since any user on the system can write derivations that populate the store (@pxref{The Store}). Thus, a different mechanism is used: instead of changing the setuid bit directly on files that are in the store, we let the system administrator @emph{declare} which programs should be setuid root. The @code{setuid-programs} field of an @code{operating-system} declaration contains a list of G-expressions denoting the names of programs to be setuid-root (@pxref{Using the Configuration System}). For instance, the @command{passwd} program, which is part of the Shadow package, can be designated by this G-expression (@pxref{G-Expressions}): @example #~(string-append #$shadow "/bin/passwd") @end example A default set of setuid programs is defined by the @code{%setuid-programs} variable of the @code{(gnu system)} module. @defvr {Scheme Variable} %setuid-programs A list of G-expressions denoting common programs that are setuid-root. The list includes commands such as @command{passwd}, @command{ping}, @command{su}, and @command{sudo}. @end defvr Under the hood, the actual setuid programs are created in the @file{/run/setuid-programs} directory at system activation time. The files in this directory refer to the ``real'' binaries, which are in the store. @node X.509 Certificates @section X.509 Certificates @cindex HTTPS, certificates @cindex X.509 certificates @cindex TLS Web servers available over HTTPS (that is, HTTP over the transport-layer security mechanism, TLS) send client programs an @dfn{X.509 certificate} that the client can then use to @emph{authenticate} the server. To do that, clients verify that the server's certificate is signed by a so-called @dfn{certificate authority} (CA). But to verify the CA's signature, clients must have first acquired the CA's certificate. Web browsers such as GNU@tie{}IceCat include their own set of CA certificates, such that they are able to verify CA signatures out-of-the-box. However, most other programs that can talk HTTPS---@command{wget}, @command{git}, @command{w3m}, etc.---need to be told where CA certificates can be found. @cindex @code{nss-certs} In Guix, this is done by adding a package that provides certificates to the @code{packages} field of the @code{operating-system} declaration (@pxref{operating-system Reference}). Guix includes one such package, @code{nss-certs}, which is a set of CA certificates provided as part of Mozilla's Network Security Services. Note that it is @emph{not} part of @code{%base-packages}, so you need to explicitly add it. The @file{/etc/ssl/certs} directory, which is where most applications and libraries look for certificates by default, points to the certificates installed globally. Unprivileged users, including users of Guix on a foreign distro, can also install their own certificate package in their profile. A number of environment variables need to be defined so that applications and libraries know where to find them. Namely, the OpenSSL library honors the @env{SSL_CERT_DIR} and @env{SSL_CERT_FILE} variables. Some applications add their own environment variables; for instance, the Git version control system honors the certificate bundle pointed to by the @env{GIT_SSL_CAINFO} environment variable. Thus, you would typically run something like: @example guix install nss-certs export SSL_CERT_DIR="$HOME/.guix-profile/etc/ssl/certs" export SSL_CERT_FILE="$HOME/.guix-profile/etc/ssl/certs/ca-certificates.crt" export GIT_SSL_CAINFO="$SSL_CERT_FILE" @end example As another example, R requires the @env{CURL_CA_BUNDLE} environment variable to point to a certificate bundle, so you would have to run something like this: @example guix install nss-certs export CURL_CA_BUNDLE="$HOME/.guix-profile/etc/ssl/certs/ca-certificates.crt" @end example For other applications you may want to look up the required environment variable in the relevant documentation. @node Name Service Switch @section Name Service Switch @cindex name service switch @cindex NSS The @code{(gnu system nss)} module provides bindings to the configuration file of the libc @dfn{name service switch} or @dfn{NSS} (@pxref{NSS Configuration File,,, libc, The GNU C Library Reference Manual}). In a nutshell, the NSS is a mechanism that allows libc to be extended with new ``name'' lookup methods for system databases, which includes host names, service names, user accounts, and more (@pxref{Name Service Switch, System Databases and Name Service Switch,, libc, The GNU C Library Reference Manual}). The NSS configuration specifies, for each system database, which lookup method is to be used, and how the various methods are chained together---for instance, under which circumstances NSS should try the next method in the list. The NSS configuration is given in the @code{name-service-switch} field of @code{operating-system} declarations (@pxref{operating-system Reference, @code{name-service-switch}}). @cindex nss-mdns @cindex .local, host name lookup As an example, the declaration below configures the NSS to use the @uref{https://0pointer.de/lennart/projects/nss-mdns/, @code{nss-mdns} back-end}, which supports host name lookups over multicast DNS (mDNS) for host names ending in @code{.local}: @lisp (name-service-switch (hosts (list %files ;first, check /etc/hosts ;; If the above did not succeed, try ;; with 'mdns_minimal'. (name-service (name "mdns_minimal") ;; 'mdns_minimal' is authoritative for ;; '.local'. When it returns "not found", ;; no need to try the next methods. (reaction (lookup-specification (not-found => return)))) ;; Then fall back to DNS. (name-service (name "dns")) ;; Finally, try with the "full" 'mdns'. (name-service (name "mdns"))))) @end lisp Do not worry: the @code{%mdns-host-lookup-nss} variable (see below) contains this configuration, so you will not have to type it if all you want is to have @code{.local} host lookup working. Note that, in this case, in addition to setting the @code{name-service-switch} of the @code{operating-system} declaration, you also need to use @code{avahi-service-type} (@pxref{Networking Services, @code{avahi-service-type}}), or @code{%desktop-services}, which includes it (@pxref{Desktop Services}). Doing this makes @code{nss-mdns} accessible to the name service cache daemon (@pxref{Base Services, @code{nscd-service}}). For convenience, the following variables provide typical NSS configurations. @defvr {Scheme Variable} %default-nss This is the default name service switch configuration, a @code{name-service-switch} object. @end defvr @defvr {Scheme Variable} %mdns-host-lookup-nss This is the name service switch configuration with support for host name lookup over multicast DNS (mDNS) for host names ending in @code{.local}. @end defvr The reference for name service switch configuration is given below. It is a direct mapping of the configuration file format of the C library , so please refer to the C library manual for more information (@pxref{NSS Configuration File,,, libc, The GNU C Library Reference Manual}). Compared to the configuration file format of libc NSS, it has the advantage not only of adding this warm parenthetic feel that we like, but also static checks: you will know about syntax errors and typos as soon as you run @command{guix system}. @deftp {Data Type} name-service-switch This is the data type representation the configuration of libc's name service switch (NSS). Each field below represents one of the supported system databases. @table @code @item aliases @itemx ethers @itemx group @itemx gshadow @itemx hosts @itemx initgroups @itemx netgroup @itemx networks @itemx password @itemx public-key @itemx rpc @itemx services @itemx shadow The system databases handled by the NSS. Each of these fields must be a list of @code{} objects (see below). @end table @end deftp @deftp {Data Type} name-service This is the data type representing an actual name service and the associated lookup action. @table @code @item name A string denoting the name service (@pxref{Services in the NSS configuration,,, libc, The GNU C Library Reference Manual}). Note that name services listed here must be visible to nscd. This is achieved by passing the @code{#:name-services} argument to @code{nscd-service} the list of packages providing the needed name services (@pxref{Base Services, @code{nscd-service}}). @item reaction An action specified using the @code{lookup-specification} macro (@pxref{Actions in the NSS configuration,,, libc, The GNU C Library Reference Manual}). For example: @lisp (lookup-specification (unavailable => continue) (success => return)) @end lisp @end table @end deftp @node Initial RAM Disk @section Initial RAM Disk @cindex initrd @cindex initial RAM disk For bootstrapping purposes, the Linux-Libre kernel is passed an @dfn{initial RAM disk}, or @dfn{initrd}. An initrd contains a temporary root file system as well as an initialization script. The latter is responsible for mounting the real root file system, and for loading any kernel modules that may be needed to achieve that. The @code{initrd-modules} field of an @code{operating-system} declaration allows you to specify Linux-libre kernel modules that must be available in the initrd. In particular, this is where you would list modules needed to actually drive the hard disk where your root partition is---although the default value of @code{initrd-modules} should cover most use cases. For example, assuming you need the @code{megaraid_sas} module in addition to the default modules to be able to access your root file system, you would write: @lisp (operating-system ;; @dots{} (initrd-modules (cons "megaraid_sas" %base-initrd-modules))) @end lisp @defvr {Scheme Variable} %base-initrd-modules This is the list of kernel modules included in the initrd by default. @end defvr Furthermore, if you need lower-level customization, the @code{initrd} field of an @code{operating-system} declaration allows you to specify which initrd you would like to use. The @code{(gnu system linux-initrd)} module provides three ways to build an initrd: the high-level @code{base-initrd} procedure and the low-level @code{raw-initrd} and @code{expression->initrd} procedures. The @code{base-initrd} procedure is intended to cover most common uses. For example, if you want to add a bunch of kernel modules to be loaded at boot time, you can define the @code{initrd} field of the operating system declaration like this: @lisp (initrd (lambda (file-systems . rest) ;; Create a standard initrd but set up networking ;; with the parameters QEMU expects by default. (apply base-initrd file-systems #:qemu-networking? #t rest))) @end lisp The @code{base-initrd} procedure also handles common use cases that involves using the system as a QEMU guest, or as a ``live'' system with volatile root file system. The @code{base-initrd} procedure is built from @code{raw-initrd} procedure. Unlike @code{base-initrd}, @code{raw-initrd} doesn't do anything high-level, such as trying to guess which kernel modules and packages should be included to the initrd. An example use of @code{raw-initrd} is when a user has a custom Linux kernel configuration and default kernel modules included by @code{base-initrd} are not available. The initial RAM disk produced by @code{base-initrd} or @code{raw-initrd} honors several options passed on the Linux kernel command line (that is, arguments passed @i{via} the @code{linux} command of GRUB, or the @code{-append} option of QEMU), notably: @table @code @item --load=@var{boot} Tell the initial RAM disk to load @var{boot}, a file containing a Scheme program, once it has mounted the root file system. Guix uses this option to yield control to a boot program that runs the service activation programs and then spawns the GNU@tie{}Shepherd, the initialization system. @item --root=@var{root} Mount @var{root} as the root file system. @var{root} can be a device name like @code{/dev/sda1}, a file system label, or a file system UUID. When unspecified, the device name from the root file system of the operating system declaration is used. @item --system=@var{system} Have @file{/run/booted-system} and @file{/run/current-system} point to @var{system}. @item modprobe.blacklist=@var{modules}@dots{} @cindex module, black-listing @cindex black list, of kernel modules Instruct the initial RAM disk as well as the @command{modprobe} command (from the kmod package) to refuse to load @var{modules}. @var{modules} must be a comma-separated list of module names---e.g., @code{usbkbd,9pnet}. @item --repl Start a read-eval-print loop (REPL) from the initial RAM disk before it tries to load kernel modules and to mount the root file system. Our marketing team calls it @dfn{boot-to-Guile}. The Schemer in you will love it. @xref{Using Guile Interactively,,, guile, GNU Guile Reference Manual}, for more information on Guile's REPL. @end table Now that you know all the features that initial RAM disks produced by @code{base-initrd} and @code{raw-initrd} provide, here is how to use it and customize it further. @cindex initrd @cindex initial RAM disk @deffn {Scheme Procedure} raw-initrd @var{file-systems} @ [#:linux-modules '()] [#:mapped-devices '()] @ [#:keyboard-layout #f] @ [#:helper-packages '()] [#:qemu-networking? #f] [#:volatile-root? #f] Return a derivation that builds a raw initrd. @var{file-systems} is a list of file systems to be mounted by the initrd, possibly in addition to the root file system specified on the kernel command line via @option{--root}. @var{linux-modules} is a list of kernel modules to be loaded at boot time. @var{mapped-devices} is a list of device mappings to realize before @var{file-systems} are mounted (@pxref{Mapped Devices}). @var{helper-packages} is a list of packages to be copied in the initrd. It may include @code{e2fsck/static} or other packages needed by the initrd to check the root file system. When true, @var{keyboard-layout} is a @code{} record denoting the desired console keyboard layout. This is done before @var{mapped-devices} are set up and before @var{file-systems} are mounted such that, should the user need to enter a passphrase or use the REPL, this happens using the intended keyboard layout. When @var{qemu-networking?} is true, set up networking with the standard QEMU parameters. When @var{virtio?} is true, load additional modules so that the initrd can be used as a QEMU guest with para-virtualized I/O drivers. When @var{volatile-root?} is true, the root file system is writable but any changes to it are lost. @end deffn @deffn {Scheme Procedure} base-initrd @var{file-systems} @ [#:mapped-devices '()] [#:keyboard-layout #f] @ [#:qemu-networking? #f] [#:volatile-root? #f] @ [#:linux-modules '()] Return as a file-like object a generic initrd, with kernel modules taken from @var{linux}. @var{file-systems} is a list of file-systems to be mounted by the initrd, possibly in addition to the root file system specified on the kernel command line via @option{--root}. @var{mapped-devices} is a list of device mappings to realize before @var{file-systems} are mounted. When true, @var{keyboard-layout} is a @code{} record denoting the desired console keyboard layout. This is done before @var{mapped-devices} are set up and before @var{file-systems} are mounted such that, should the user need to enter a passphrase or use the REPL, this happens using the intended keyboard layout. @var{qemu-networking?} and @var{volatile-root?} behaves as in @code{raw-initrd}. The initrd is automatically populated with all the kernel modules necessary for @var{file-systems} and for the given options. Additional kernel modules can be listed in @var{linux-modules}. They will be added to the initrd, and loaded at boot time in the order in which they appear. @end deffn Needless to say, the initrds we produce and use embed a statically-linked Guile, and the initialization program is a Guile program. That gives a lot of flexibility. The @code{expression->initrd} procedure builds such an initrd, given the program to run in that initrd. @deffn {Scheme Procedure} expression->initrd @var{exp} @ [#:guile %guile-3.0-static-stripped] [#:name "guile-initrd"] Return as a file-like object a Linux initrd (a gzipped cpio archive) containing @var{guile} and that evaluates @var{exp}, a G-expression, upon booting. All the derivations referenced by @var{exp} are automatically copied to the initrd. @end deffn @node Bootloader Configuration @section Bootloader Configuration @cindex bootloader @cindex boot loader The operating system supports multiple bootloaders. The bootloader is configured using @code{bootloader-configuration} declaration. All the fields of this structure are bootloader agnostic except for one field, @code{bootloader} that indicates the bootloader to be configured and installed. Some of the bootloaders do not honor every field of @code{bootloader-configuration}. For instance, the extlinux bootloader does not support themes and thus ignores the @code{theme} field. @deftp {Data Type} bootloader-configuration The type of a bootloader configuration declaration. @table @asis @item @code{bootloader} @cindex EFI, bootloader @cindex UEFI, bootloader @cindex BIOS, bootloader The bootloader to use, as a @code{bootloader} object. For now @code{grub-bootloader}, @code{grub-efi-bootloader}, @code{grub-efi-netboot-bootloader}, @code{extlinux-bootloader} and @code{u-boot-bootloader} are supported. @cindex ARM, bootloaders @cindex AArch64, bootloaders Available bootloaders are described in @code{(gnu bootloader @dots{})} modules. In particular, @code{(gnu bootloader u-boot)} contains definitions of bootloaders for a wide range of ARM and AArch64 systems, using the @uref{https://www.denx.de/wiki/U-Boot/, U-Boot bootloader}. @vindex grub-efi-bootloader @code{grub-efi-bootloader} allows to boot on modern systems using the @dfn{Unified Extensible Firmware Interface} (UEFI). This is what you should use if the installation image contains a @file{/sys/firmware/efi} directory when you boot it on your system. @vindex grub-bootloader @code{grub-bootloader} allows you to boot in particular Intel-based machines in ``legacy'' BIOS mode. @vindex grub-efi-netboot-bootloader @code{grub-efi-netboot-bootloader} allows you to boot your system over network through TFTP. In combination with an NFS root file system this allows you to build a diskless Guix system. The installation of the @code{grub-efi-netboot-bootloader} generates the content of the TFTP root directory at @code{target} (@pxref{Bootloader Configuration, @code{target}}), to be served by a TFTP server. You may want to mount your TFTP server directory onto @code{target} to move the required files to the TFTP server automatically. If you plan to use an NFS root file system as well (actually if you mount the store from an NFS share), then the TFTP server needs to serve the file @file{/boot/grub/grub.cfg} and other files from the store (like GRUBs background image, the kernel (@pxref{operating-system Reference, @code{kernel}}) and the initrd (@pxref{operating-system Reference, @code{initrd}})), too. All these files from the store will be accessed by GRUB through TFTP with their normal store path, for example as @file{tftp://tftp-server/gnu/store/…-initrd/initrd.cpio.gz}. Two symlinks are created to make this possible. The first symlink is @code{target}@file{/efi/Guix/boot/grub/grub.cfg} pointing to @file{../../../boot/grub/grub.cfg}, where @code{target} may be @file{/boot}. In this case the link is not leaving the served TFTP root directory, but otherwise it does. The second link is @code{target}@file{/gnu/store} and points to @file{../gnu/store}. This link is leaving the served TFTP root directory. The assumption behind all this is that you have an NFS server exporting the root file system for your Guix system, and additionally a TFTP server exporting your @code{target} directory—usually @file{/boot}—from that same root file system for your Guix system. In this constellation the symlinks will work. For other constellations you will have to program your own bootloader installer, which then takes care to make necessary files from the store accessible through TFTP, for example by copying them into the TFTP root directory at @code{target}. It is important to note that symlinks pointing outside the TFTP root directory may need to be allowed in the configuration of your TFTP server. Further the store link exposes the whole store through TFTP. Both points need to be considered carefully for security aspects. Beside the @code{grub-efi-netboot-bootloader}, the already mentioned TFTP and NFS servers, you also need a properly configured DHCP server to make the booting over netboot possible. For all this we can currently only recommend you to look for instructions about @acronym{PXE, Preboot eXecution Environment}. @item @code{target} This is a string denoting the target onto which to install the bootloader. The interpretation depends on the bootloader in question. For @code{grub-bootloader}, for example, it should be a device name understood by the bootloader @command{installer} command, such as @code{/dev/sda} or @code{(hd0)} (@pxref{Invoking grub-install,,, grub, GNU GRUB Manual}). For @code{grub-efi-bootloader}, it should be the mount point of the EFI file system, usually @file{/boot/efi}. For @code{grub-efi-netboot-bootloader}, @code{target} should be the mount point corresponding to the TFTP root directory of your TFTP server. @item @code{menu-entries} (default: @code{()}) A possibly empty list of @code{menu-entry} objects (see below), denoting entries to appear in the bootloader menu, in addition to the current system entry and the entry pointing to previous system generations. @item @code{default-entry} (default: @code{0}) The index of the default boot menu entry. Index 0 is for the entry of the current system. @item @code{timeout} (default: @code{5}) The number of seconds to wait for keyboard input before booting. Set to 0 to boot immediately, and to -1 to wait indefinitely. @cindex keyboard layout, for the bootloader @item @code{keyboard-layout} (default: @code{#f}) If this is @code{#f}, the bootloader's menu (if any) uses the default keyboard layout, usually US@tie{}English (``qwerty''). Otherwise, this must be a @code{keyboard-layout} object (@pxref{Keyboard Layout}). @quotation Note This option is currently ignored by bootloaders other than @code{grub} and @code{grub-efi}. @end quotation @item @code{theme} (default: @var{#f}) The bootloader theme object describing the theme to use. If no theme is provided, some bootloaders might use a default theme, that's true for GRUB. @item @code{terminal-outputs} (default: @code{'(gfxterm)}) The output terminals used for the bootloader boot menu, as a list of symbols. GRUB accepts the values: @code{console}, @code{serial}, @code{serial_@{0-3@}}, @code{gfxterm}, @code{vga_text}, @code{mda_text}, @code{morse}, and @code{pkmodem}. This field corresponds to the GRUB variable @code{GRUB_TERMINAL_OUTPUT} (@pxref{Simple configuration,,, grub,GNU GRUB manual}). @item @code{terminal-inputs} (default: @code{'()}) The input terminals used for the bootloader boot menu, as a list of symbols. For GRUB, the default is the native platform terminal as determined at run-time. GRUB accepts the values: @code{console}, @code{serial}, @code{serial_@{0-3@}}, @code{at_keyboard}, and @code{usb_keyboard}. This field corresponds to the GRUB variable @code{GRUB_TERMINAL_INPUT} (@pxref{Simple configuration,,, grub,GNU GRUB manual}). @item @code{serial-unit} (default: @code{#f}) The serial unit used by the bootloader, as an integer from 0 to 3. For GRUB, it is chosen at run-time; currently GRUB chooses 0, which corresponds to COM1 (@pxref{Serial terminal,,, grub,GNU GRUB manual}). @item @code{serial-speed} (default: @code{#f}) The speed of the serial interface, as an integer. For GRUB, the default value is chosen at run-time; currently GRUB chooses 9600@tie{}bps (@pxref{Serial terminal,,, grub,GNU GRUB manual}). @end table @end deftp @cindex dual boot @cindex boot menu Should you want to list additional boot menu entries @i{via} the @code{menu-entries} field above, you will need to create them with the @code{menu-entry} form. For example, imagine you want to be able to boot another distro (hard to imagine!), you can define a menu entry along these lines: @lisp (menu-entry (label "The Other Distro") (linux "/boot/old/vmlinux-2.6.32") (linux-arguments '("root=/dev/sda2")) (initrd "/boot/old/initrd")) @end lisp Details below. @deftp {Data Type} menu-entry The type of an entry in the bootloader menu. @table @asis @item @code{label} The label to show in the menu---e.g., @code{"GNU"}. @item @code{linux} (default: @code{#f}) The Linux kernel image to boot, for example: @lisp (file-append linux-libre "/bzImage") @end lisp For GRUB, it is also possible to specify a device explicitly in the file path using GRUB's device naming convention (@pxref{Naming convention,,, grub, GNU GRUB manual}), for example: @example "(hd0,msdos1)/boot/vmlinuz" @end example If the device is specified explicitly as above, then the @code{device} field is ignored entirely. @item @code{linux-arguments} (default: @code{()}) The list of extra Linux kernel command-line arguments---e.g., @code{("console=ttyS0")}. @item @code{initrd} (default: @code{#f}) A G-Expression or string denoting the file name of the initial RAM disk to use (@pxref{G-Expressions}). @item @code{device} (default: @code{#f}) The device where the kernel and initrd are to be found---i.e., for GRUB, @dfn{root} for this menu entry (@pxref{root,,, grub, GNU GRUB manual}). This may be a file system label (a string), a file system UUID (a bytevector, @pxref{File Systems}), or @code{#f}, in which case the bootloader will search the device containing the file specified by the @code{linux} field (@pxref{search,,, grub, GNU GRUB manual}). It must @emph{not} be an OS device name such as @file{/dev/sda1}. @item @code{multiboot-kernel} (default: @code{#f}) The kernel to boot in Multiboot-mode (@pxref{multiboot,,, grub, GNU GRUB manual}). When this field is set, a Multiboot menu-entry is generated. For example: @lisp (file-append mach "/boot/gnumach") @end lisp @item @code{multiboot-arguments} (default: @code{()}) The list of extra command-line arguments for the multiboot-kernel. @item @code{multiboot-modules} (default: @code{()}) The list of commands for loading Multiboot modules. For example: @lisp (list (list (file-append hurd "/hurd/ext2fs.static") "ext2fs" @dots{}) (list (file-append libc "/lib/ld.so.1") "exec" @dots{})) @end lisp @end table @end deftp @cindex HDPI @cindex HiDPI @cindex resolution @c FIXME: Write documentation once it's stable. For now only GRUB has theme support. GRUB themes are created using the @code{grub-theme} form, which is not fully documented yet. @deftp {Data Type} grub-theme Data type representing the configuration of the GRUB theme. @table @asis @item @code{gfxmode} (default: @code{'("auto")}) The GRUB @code{gfxmode} to set (a list of screen resolution strings, @pxref{gfxmode,,, grub, GNU GRUB manual}). @end table @end deftp @deffn {Scheme Procedure} grub-theme Return the default GRUB theme used by the operating system if no @code{theme} field is specified in @code{bootloader-configuration} record. It comes with a fancy background image displaying the GNU and Guix logos. @end deffn For example, to override the default resolution, you may use something like @lisp (bootloader (bootloader-configuration ;; @dots{} (theme (grub-theme (inherit (grub-theme)) (gfxmode '("1024x786x32" "auto")))))) @end lisp @node Invoking guix system @section Invoking @code{guix system} Once you have written an operating system declaration as seen in the previous section, it can be @dfn{instantiated} using the @command{guix system} command. The synopsis is: @example guix system @var{options}@dots{} @var{action} @var{file} @end example @var{file} must be the name of a file containing an @code{operating-system} declaration. @var{action} specifies how the operating system is instantiated. Currently the following values are supported: @table @code @item search Display available service type definitions that match the given regular expressions, sorted by relevance: @cindex HDPI @cindex HiDPI @cindex resolution @example $ guix system search console name: console-fonts location: gnu/services/base.scm:806:2 extends: shepherd-root description: Install the given fonts on the specified ttys (fonts are per + virtual console on GNU/Linux). The value of this service is a list of + tty/font pairs. The font can be the name of a font provided by the `kbd' + package or any valid argument to `setfont', as in this example: + + '(("tty1" . "LatGrkCyr-8x16") + ("tty2" . (file-append + font-tamzen + "/share/kbd/consolefonts/TamzenForPowerline10x20.psf")) + ("tty3" . (file-append + font-terminus + "/share/consolefonts/ter-132n"))) ; for HDPI relevance: 9 name: mingetty location: gnu/services/base.scm:1190:2 extends: shepherd-root description: Provide console login using the `mingetty' program. relevance: 2 name: login location: gnu/services/base.scm:860:2 extends: pam description: Provide a console log-in service as specified by its + configuration value, a `login-configuration' object. relevance: 2 @dots{} @end example As for @command{guix package --search}, the result is written in @code{recutils} format, which makes it easy to filter the output (@pxref{Top, GNU recutils databases,, recutils, GNU recutils manual}). @item reconfigure Build the operating system described in @var{file}, activate it, and switch to it@footnote{This action (and the related actions @code{switch-generation} and @code{roll-back}) are usable only on systems already running Guix System.}. @quotation Note @c The paragraph below refers to the problem discussed at @c . It is highly recommended to run @command{guix pull} once before you run @command{guix system reconfigure} for the first time (@pxref{Invoking guix pull}). Failing to do that you would see an older version of Guix once @command{reconfigure} has completed. @end quotation This effects all the configuration specified in @var{file}: user accounts, system services, global package list, setuid programs, etc. The command starts system services specified in @var{file} that are not currently running; if a service is currently running this command will arrange for it to be upgraded the next time it is stopped (e.g.@: by @code{herd stop X} or @code{herd restart X}). This command creates a new generation whose number is one greater than the current generation (as reported by @command{guix system list-generations}). If that generation already exists, it will be overwritten. This behavior mirrors that of @command{guix package} (@pxref{Invoking guix package}). It also adds a bootloader menu entry for the new OS configuration, ---unless @option{--no-bootloader} is passed. For GRUB, it moves entries for older configurations to a submenu, allowing you to choose an older system generation at boot time should you need it. @cindex provenance tracking, of the operating system Upon completion, the new system is deployed under @file{/run/current-system}. This directory contains @dfn{provenance meta-data}: the list of channels in use (@pxref{Channels}) and @var{file} itself, when available. You can view it by running: @example guix system describe @end example This information is useful should you later want to inspect how this particular generation was built. In fact, assuming @var{file} is self-contained, you can later rebuild generation @var{n} of your operating system with: @example guix time-machine \ -C /var/guix/profiles/system-@var{n}-link/channels.scm -- \ system reconfigure \ /var/guix/profiles/system-@var{n}-link/configuration.scm @end example You can think of it as some sort of built-in version control! Your system is not just a binary artifact: @emph{it carries its own source}. @xref{Service Reference, @code{provenance-service-type}}, for more information on provenance tracking. By default, @command{reconfigure} @emph{prevents you from downgrading your system}, which could (re)introduce security vulnerabilities and also cause problems with ``stateful'' services such as database management systems. You can override that behavior by passing @option{--allow-downgrades}. @item switch-generation @cindex generations Switch to an existing system generation. This action atomically switches the system profile to the specified system generation. It also rearranges the system's existing bootloader menu entries. It makes the menu entry for the specified system generation the default, and it moves the entries for the other generations to a submenu, if supported by the bootloader being used. The next time the system boots, it will use the specified system generation. The bootloader itself is not being reinstalled when using this command. Thus, the installed bootloader is used with an updated configuration file. The target generation can be specified explicitly by its generation number. For example, the following invocation would switch to system generation 7: @example guix system switch-generation 7 @end example The target generation can also be specified relative to the current generation with the form @code{+N} or @code{-N}, where @code{+3} means ``3 generations ahead of the current generation,'' and @code{-1} means ``1 generation prior to the current generation.'' When specifying a negative value such as @code{-1}, you must precede it with @code{--} to prevent it from being parsed as an option. For example: @example guix system switch-generation -- -1 @end example Currently, the effect of invoking this action is @emph{only} to switch the system profile to an existing generation and rearrange the bootloader menu entries. To actually start using the target system generation, you must reboot after running this action. In the future, it will be updated to do the same things as @command{reconfigure}, like activating and deactivating services. This action will fail if the specified generation does not exist. @item roll-back @cindex rolling back Switch to the preceding system generation. The next time the system boots, it will use the preceding system generation. This is the inverse of @command{reconfigure}, and it is exactly the same as invoking @command{switch-generation} with an argument of @code{-1}. Currently, as with @command{switch-generation}, you must reboot after running this action to actually start using the preceding system generation. @item delete-generations @cindex deleting system generations @cindex saving space Delete system generations, making them candidates for garbage collection (@pxref{Invoking guix gc}, for information on how to run the ``garbage collector''). This works in the same way as @samp{guix package --delete-generations} (@pxref{Invoking guix package, @option{--delete-generations}}). With no arguments, all system generations but the current one are deleted: @example guix system delete-generations @end example You can also select the generations you want to delete. The example below deletes all the system generations that are more than two month old: @example guix system delete-generations 2m @end example Running this command automatically reinstalls the bootloader with an updated list of menu entries---e.g., the ``old generations'' sub-menu in GRUB no longer lists the generations that have been deleted. @item build Build the derivation of the operating system, which includes all the configuration files and programs needed to boot and run the system. This action does not actually install anything. @item init Populate the given directory with all the files necessary to run the operating system specified in @var{file}. This is useful for first-time installations of Guix System. For instance: @example guix system init my-os-config.scm /mnt @end example copies to @file{/mnt} all the store items required by the configuration specified in @file{my-os-config.scm}. This includes configuration files, packages, and so on. It also creates other essential files needed for the system to operate correctly---e.g., the @file{/etc}, @file{/var}, and @file{/run} directories, and the @file{/bin/sh} file. This command also installs bootloader on the target specified in @file{my-os-config}, unless the @option{--no-bootloader} option was passed. @item vm @cindex virtual machine @cindex VM @anchor{guix system vm} Build a virtual machine that contains the operating system declared in @var{file}, and return a script to run that virtual machine (VM). @quotation Note The @code{vm} action and others below can use KVM support in the Linux-libre kernel. Specifically, if the machine has hardware virtualization support, the corresponding KVM kernel module should be loaded, and the @file{/dev/kvm} device node must exist and be readable and writable by the user and by the build users of the daemon (@pxref{Build Environment Setup}). @end quotation Arguments given to the script are passed to QEMU as in the example below, which enables networking and requests 1@tie{}GiB of RAM for the emulated machine: @example $ /gnu/store/@dots{}-run-vm.sh -m 1024 -smp 2 -net user,model=virtio-net-pci @end example The VM shares its store with the host system. Additional file systems can be shared between the host and the VM using the @option{--share} and @option{--expose} command-line options: the former specifies a directory to be shared with write access, while the latter provides read-only access to the shared directory. The example below creates a VM in which the user's home directory is accessible read-only, and where the @file{/exchange} directory is a read-write mapping of @file{$HOME/tmp} on the host: @example guix system vm my-config.scm \ --expose=$HOME --share=$HOME/tmp=/exchange @end example On GNU/Linux, the default is to boot directly to the kernel; this has the advantage of requiring only a very tiny root disk image since the store of the host can then be mounted. The @option{--full-boot} option forces a complete boot sequence, starting with the bootloader. This requires more disk space since a root image containing at least the kernel, initrd, and bootloader data files must be created. The @option{--image-size} option can be used to specify the size of the image. @cindex System images, creation in various formats @cindex Creating system images in various formats @item vm-image @itemx disk-image @itemx docker-image Return a virtual machine, disk image, or Docker image of the operating system declared in @var{file} that stands alone. By default, @command{guix system} estimates the size of the image needed to store the system, but you can use the @option{--image-size} option to specify a value. Docker images are built to contain exactly what they need, so the @option{--image-size} option is ignored in the case of @code{docker-image}. @cindex disk-image, creating disk images The @code{disk-image} command can produce various image types. The image type can be selected using the @option{--image-type} option. It defaults to @code{raw}. When its value is @code{iso9660}, the @option{--label} option can be used to specify a volume ID with @code{disk-image}. By default, the root file system of a disk image is mounted non-volatile; the @option{--volatile} option can be provided to make it volatile instead. When using @code{disk-image}, the bootloader installed on the generated image is taken from the provided @code{operating-system} definition. The following example demonstrates how to generate an image that uses the @code{grub-efi-bootloader} bootloader and boot it with QEMU: @example image=$(guix system disk-image --image-type=qcow2 \ gnu/system/examples/lightweight-desktop.tmpl) cp $image /tmp/my-image.qcow2 chmod +w /tmp/my-image.qcow2 qemu-system-x86_64 -enable-kvm -hda /tmp/my-image.qcow2 -m 1000 \ -bios $(guix build ovmf)/share/firmware/ovmf_x64.bin @end example When using the @code{raw} image type, a raw disk image is produced; it can be copied as is to a USB stick, for instance. Assuming @code{/dev/sdc} is the device corresponding to a USB stick, one can copy the image to it using the following command: @example # dd if=$(guix system disk-image my-os.scm) of=/dev/sdc status=progress @end example The @code{--list-image-types} command lists all the available image types. @cindex vm-image, creating virtual machine images When using @code{vm-image}, the returned image is in qcow2 format, which the QEMU emulator can efficiently use. @xref{Running Guix in a VM}, for more information on how to run the image in a virtual machine. The @code{grub-bootloader} bootloader is always used independently of what is declared in the @code{operating-system} file passed as argument. This is to make it easier to work with QEMU, which uses the SeaBIOS BIOS by default, expecting a bootloader to be installed in the Master Boot Record (MBR). @cindex docker-image, creating docker images When using @code{docker-image}, a Docker image is produced. Guix builds the image from scratch, not from a pre-existing Docker base image. As a result, it contains @emph{exactly} what you define in the operating system configuration file. You can then load the image and launch a Docker container using commands like the following: @example image_id="`docker load < guix-system-docker-image.tar.gz`" container_id="`docker create $image_id`" docker start $container_id @end example This command starts a new Docker container from the specified image. It will boot the Guix system in the usual manner, which means it will start any services you have defined in the operating system configuration. You can get an interactive shell running in the container using @command{docker exec}: @example docker exec -ti $container_id /run/current-system/profile/bin/bash --login @end example Depending on what you run in the Docker container, it may be necessary to give the container additional permissions. For example, if you intend to build software using Guix inside of the Docker container, you may need to pass the @option{--privileged} option to @code{docker create}. Last, the @option{--network} option applies to @command{guix system docker-image}: it produces an image where network is supposedly shared with the host, and thus without services like nscd or NetworkManager. @item container Return a script to run the operating system declared in @var{file} within a container. Containers are a set of lightweight isolation mechanisms provided by the kernel Linux-libre. Containers are substantially less resource-demanding than full virtual machines since the kernel, shared objects, and other resources can be shared with the host system; this also means they provide thinner isolation. Currently, the script must be run as root in order to support more than a single user and group. The container shares its store with the host system. As with the @code{vm} action (@pxref{guix system vm}), additional file systems to be shared between the host and container can be specified using the @option{--share} and @option{--expose} options: @example guix system container my-config.scm \ --expose=$HOME --share=$HOME/tmp=/exchange @end example @quotation Note This option requires Linux-libre 3.19 or newer. @end quotation @end table @var{options} can contain any of the common build options (@pxref{Common Build Options}). In addition, @var{options} can contain one of the following: @table @option @item --expression=@var{expr} @itemx -e @var{expr} Consider the operating-system @var{expr} evaluates to. This is an alternative to specifying a file which evaluates to an operating system. This is used to generate the Guix system installer @pxref{Building the Installation Image}). @item --system=@var{system} @itemx -s @var{system} Attempt to build for @var{system} instead of the host system type. This works as per @command{guix build} (@pxref{Invoking guix build}). @item --derivation @itemx -d Return the derivation file name of the given operating system without building anything. @cindex provenance tracking, of the operating system @item --save-provenance As discussed above, @command{guix system init} and @command{guix system reconfigure} always save provenance information @i{via} a dedicated service (@pxref{Service Reference, @code{provenance-service-type}}). However, other commands don't do that by default. If you wish to, say, create a virtual machine image that contains provenance information, you can run: @example guix system vm-image --save-provenance config.scm @end example That way, the resulting image will effectively ``embed its own source'' in the form of meta-data in @file{/run/current-system}. With that information, one can rebuild the image to make sure it really contains what it pretends to contain; or they could use that to derive a variant of the image. @item --image-type=@var{type} @itemx -t @var{type} For the @code{disk-image} action, create an image with given @var{type}. When this option is omitted, @command{guix system} uses the @code{raw} image type. @cindex ISO-9660 format @cindex CD image format @cindex DVD image format @option{--image-type=iso9660} produces an ISO-9660 image, suitable for burning on CDs and DVDs. @item --image-size=@var{size} For the @code{vm-image} and @code{disk-image} actions, create an image of the given @var{size}. @var{size} may be a number of bytes, or it may include a unit as a suffix (@pxref{Block size, size specifications,, coreutils, GNU Coreutils}). When this option is omitted, @command{guix system} computes an estimate of the image size as a function of the size of the system declared in @var{file}. @item --network @itemx -N For the @code{container} action, allow containers to access the host network, that is, do not create a network namespace. @item --root=@var{file} @itemx -r @var{file} Make @var{file} a symlink to the result, and register it as a garbage collector root. @item --skip-checks Skip pre-installation safety checks. By default, @command{guix system init} and @command{guix system reconfigure} perform safety checks: they make sure the file systems that appear in the @code{operating-system} declaration actually exist (@pxref{File Systems}), and that any Linux kernel modules that may be needed at boot time are listed in @code{initrd-modules} (@pxref{Initial RAM Disk}). Passing this option skips these tests altogether. @item --allow-downgrades Instruct @command{guix system reconfigure} to allow system downgrades. By default, @command{reconfigure} prevents you from downgrading your system. It achieves that by comparing the provenance info of your system (shown by @command{guix system describe}) with that of your @command{guix} command (shown by @command{guix describe}). If the commits for @command{guix} are not descendants of those used for your system, @command{guix system reconfigure} errors out. Passing @option{--allow-downgrades} allows you to bypass these checks. @quotation Note Make sure you understand its security implications before using @option{--allow-downgrades}. @end quotation @cindex on-error @cindex on-error strategy @cindex error strategy @item --on-error=@var{strategy} Apply @var{strategy} when an error occurs when reading @var{file}. @var{strategy} may be one of the following: @table @code @item nothing-special Report the error concisely and exit. This is the default strategy. @item backtrace Likewise, but also display a backtrace. @item debug Report the error and enter Guile's debugger. From there, you can run commands such as @code{,bt} to get a backtrace, @code{,locals} to display local variable values, and more generally inspect the state of the program. @xref{Debug Commands,,, guile, GNU Guile Reference Manual}, for a list of available debugging commands. @end table @end table Once you have built, configured, re-configured, and re-re-configured your Guix installation, you may find it useful to list the operating system generations available on disk---and that you can choose from the bootloader boot menu: @table @code @item describe Describe the current system generation: its file name, the kernel and bootloader used, etc., as well as provenance information when available. @item list-generations List a summary of each generation of the operating system available on disk, in a human-readable way. This is similar to the @option{--list-generations} option of @command{guix package} (@pxref{Invoking guix package}). Optionally, one can specify a pattern, with the same syntax that is used in @command{guix package --list-generations}, to restrict the list of generations displayed. For instance, the following command displays generations that are up to 10 days old: @example $ guix system list-generations 10d @end example @end table The @command{guix system} command has even more to offer! The following sub-commands allow you to visualize how your system services relate to each other: @anchor{system-extension-graph} @table @code @item extension-graph Emit to standard output the @dfn{service extension graph} of the operating system defined in @var{file} (@pxref{Service Composition}, for more information on service extensions). By default the output is in Dot/Graphviz format, but you can choose a different format with @option{--graph-backend}, as with @command{guix graph} (@pxref{Invoking guix graph, @option{--backend}}): The command: @example $ guix system extension-graph @var{file} | xdot - @end example shows the extension relations among services. @anchor{system-shepherd-graph} @item shepherd-graph Emit to standard output the @dfn{dependency graph} of shepherd services of the operating system defined in @var{file}. @xref{Shepherd Services}, for more information and for an example graph. Again, the default output format is Dot/Graphviz, but you can pass @option{--graph-backend} to select a different one. @end table @node Invoking guix deploy @section Invoking @code{guix deploy} We've already seen @code{operating-system} declarations used to manage a machine's configuration locally. Suppose you need to configure multiple machines, though---perhaps you're managing a service on the web that's comprised of several servers. @command{guix deploy} enables you to use those same @code{operating-system} declarations to manage multiple remote hosts at once as a logical ``deployment''. @quotation Note The functionality described in this section is still under development and is subject to change. Get in touch with us on @email{guix-devel@@gnu.org}! @end quotation @example guix deploy @var{file} @end example Such an invocation will deploy the machines that the code within @var{file} evaluates to. As an example, @var{file} might contain a definition like this: @lisp ;; This is a Guix deployment of a "bare bones" setup, with ;; no X11 display server, to a machine with an SSH daemon ;; listening on localhost:2222. A configuration such as this ;; may be appropriate for virtual machine with ports ;; forwarded to the host's loopback interface. (use-service-modules networking ssh) (use-package-modules bootloaders) (define %system (operating-system (host-name "gnu-deployed") (timezone "Etc/UTC") (bootloader (bootloader-configuration (bootloader grub-bootloader) (target "/dev/vda") (terminal-outputs '(console)))) (file-systems (cons (file-system (mount-point "/") (device "/dev/vda1") (type "ext4")) %base-file-systems)) (services (append (list (service dhcp-client-service-type) (service openssh-service-type (openssh-configuration (permit-root-login #t) (allow-empty-passwords? #t)))) %base-services)))) (list (machine (operating-system %system) (environment managed-host-environment-type) (configuration (machine-ssh-configuration (host-name "localhost") (system "x86_64-linux") (user "alice") (identity "./id_rsa") (port 2222))))) @end lisp The file should evaluate to a list of @var{machine} objects. This example, upon being deployed, will create a new generation on the remote system realizing the @code{operating-system} declaration @code{%system}. @code{environment} and @code{configuration} specify how the machine should be provisioned---that is, how the computing resources should be created and managed. The above example does not create any resources, as a @code{'managed-host} is a machine that is already running the Guix system and available over the network. This is a particularly simple case; a more complex deployment may involve, for example, starting virtual machines through a Virtual Private Server (VPS) provider. In such a case, a different @var{environment} type would be used. Do note that you first need to generate a key pair on the coordinator machine to allow the daemon to export signed archives of files from the store (@pxref{Invoking guix archive}), though this step is automatic on Guix System: @example # guix archive --generate-key @end example @noindent Each target machine must authorize the key of the master machine so that it accepts store items it receives from the coordinator: @example # guix archive --authorize < coordinator-public-key.txt @end example @code{user}, in this example, specifies the name of the user account to log in as to perform the deployment. Its default value is @code{root}, but root login over SSH may be forbidden in some cases. To work around this, @command{guix deploy} can log in as an unprivileged user and employ @code{sudo} to escalate privileges. This will only work if @code{sudo} is currently installed on the remote and can be invoked non-interactively as @code{user}. That is, the line in @code{sudoers} granting @code{user} the ability to use @code{sudo} must contain the @code{NOPASSWD} tag. This can be accomplished with the following operating system configuration snippet: @lisp (use-modules ... (gnu system)) ;for %sudoers-specification (define %user "username") (operating-system ... (sudoers-file (plain-file "sudoers" (string-append (plain-file-content %sudoers-specification) (format #f "~a ALL = NOPASSWD: ALL~%" %user))))) @end lisp For more information regarding the format of the @file{sudoers} file, consult @command{man sudoers}. @deftp {Data Type} machine This is the data type representing a single machine in a heterogeneous Guix deployment. @table @asis @item @code{operating-system} The object of the operating system configuration to deploy. @item @code{environment} An @code{environment-type} describing how the machine should be provisioned. @item @code{configuration} (default: @code{#f}) An object describing the configuration for the machine's @code{environment}. If the @code{environment} has a default configuration, @code{#f} may be used. If @code{#f} is used for an environment with no default configuration, however, an error will be thrown. @end table @end deftp @deftp {Data Type} machine-ssh-configuration This is the data type representing the SSH client parameters for a machine with an @code{environment} of @code{managed-host-environment-type}. @table @asis @item @code{host-name} @item @code{build-locally?} (default: @code{#t}) If false, system derivations will be built on the machine being deployed to. @item @code{system} The system type describing the architecture of the machine being deployed to---e.g., @code{"x86_64-linux"}. @item @code{authorize?} (default: @code{#t}) If true, the coordinator's signing key will be added to the remote's ACL keyring. @item @code{port} (default: @code{22}) @item @code{user} (default: @code{"root"}) @item @code{identity} (default: @code{#f}) If specified, the path to the SSH private key to use to authenticate with the remote host. @item @code{host-key} (default: @code{#f}) This should be the SSH host key of the machine, which looks like this: @example ssh-ed25519 AAAAC3Nz@dots{} root@@example.org @end example When @code{host-key} is @code{#f}, the server is authenticated against the @file{~/.ssh/known_hosts} file, just like the OpenSSH @command{ssh} client does. @item @code{allow-downgrades?} (default: @code{#f}) Whether to allow potential downgrades. Like @command{guix system reconfigure}, @command{guix deploy} compares the channel commits currently deployed on the remote host (as returned by @command{guix system describe}) to those currently in use (as returned by @command{guix describe}) to determine whether commits currently in use are descendants of those deployed. When this is not the case and @code{allow-downgrades?} is false, it raises an error. This ensures you do not accidentally downgrade remote machines. @end table @end deftp @deftp {Data Type} digital-ocean-configuration This is the data type describing the Droplet that should be created for a machine with an @code{environment} of @code{digital-ocean-environment-type}. @table @asis @item @code{ssh-key} The path to the SSH private key to use to authenticate with the remote host. In the future, this field may not exist. @item @code{tags} A list of string ``tags'' that uniquely identify the machine. Must be given such that no two machines in the deployment have the same set of tags. @item @code{region} A Digital Ocean region slug, such as @code{"nyc3"}. @item @code{size} A Digital Ocean size slug, such as @code{"s-1vcpu-1gb"} @item @code{enable-ipv6?} Whether or not the droplet should be created with IPv6 networking. @end table @end deftp @node Running Guix in a VM @section Running Guix in a Virtual Machine @cindex virtual machine To run Guix in a virtual machine (VM), one can use the pre-built Guix VM image distributed at @url{@value{BASE-URL}/guix-system-vm-image-@value{VERSION}.x86_64-linux.xz}. This image is a compressed image in QCOW format. You will first need to decompress with @command{xz -d}, and then you can pass it to an emulator such as QEMU (see below for details). This image boots the Xfce graphical environment and it contains some commonly used tools. You can install more software in the image by running @command{guix package} in a terminal (@pxref{Invoking guix package}). You can also reconfigure the system based on its initial configuration file available as @file{/run/current-system/configuration.scm} (@pxref{Using the Configuration System}). Instead of using this pre-built image, one can also build their own virtual machine image using @command{guix system vm-image} (@pxref{Invoking guix system}). The returned image is in qcow2 format, which the @uref{https://qemu.org/, QEMU emulator} can efficiently use. @cindex QEMU If you built your own image, you must copy it out of the store (@pxref{The Store}) and give yourself permission to write to the copy before you can use it. When invoking QEMU, you must choose a system emulator that is suitable for your hardware platform. Here is a minimal QEMU invocation that will boot the result of @command{guix system vm-image} on x86_64 hardware: @example $ qemu-system-x86_64 \ -nic user,model=virtio-net-pci \ -enable-kvm -m 1024 \ -device virtio-blk,drive=myhd \ -drive if=none,file=/tmp/qemu-image,id=myhd @end example Here is what each of these options means: @table @code @item qemu-system-x86_64 This specifies the hardware platform to emulate. This should match the host. @item -nic user,model=virtio-net-pci Enable the unprivileged user-mode network stack. The guest OS can access the host but not vice versa. This is the simplest way to get the guest OS online. @code{model} specifies which network device to emulate: @code{virtio-net-pci} is a special device made for virtualized operating systems and recommended for most uses. Assuming your hardware platform is x86_64, you can get a list of available NIC models by running @command{qemu-system-x86_64 -nic model=help}. @item -enable-kvm If your system has hardware virtualization extensions, enabling the virtual machine support (KVM) of the Linux kernel will make things run faster. @c To run Xfce + 'guix pull', we need at least 1G of RAM. @item -m 1024 RAM available to the guest OS, in mebibytes. Defaults to 128@tie{}MiB, which may be insufficient for some operations. @item -device virtio-blk,drive=myhd Create a @code{virtio-blk} drive called ``myhd''. @code{virtio-blk} is a ``paravirtualization'' mechanism for block devices that allows QEMU to achieve better performance than if it were emulating a complete disk drive. See the QEMU and KVM documentation for more info. @item -drive if=none,file=/tmp/qemu-image,id=myhd Use our QCOW image, the @file{/tmp/qemu-image} file, as the backing store of the ``myhd'' drive. @end table The default @command{run-vm.sh} script that is returned by an invocation of @command{guix system vm} does not add a @command{-nic user} flag by default. To get network access from within the vm add the @code{(dhcp-client-service)} to your system definition and start the VM using @command{`guix system vm config.scm` -nic user}. An important caveat of using @command{-nic user} for networking is that @command{ping} will not work, because it uses the ICMP protocol. You'll have to use a different command to check for network connectivity, for example @command{guix download}. @subsection Connecting Through SSH @cindex SSH @cindex SSH server To enable SSH inside a VM you need to add an SSH server like @code{openssh-service-type} to your VM (@pxref{Networking Services, @code{openssh-service-type}}). In addition you need to forward the SSH port, 22 by default, to the host. You can do this with @example `guix system vm config.scm` -nic user,model=virtio-net-pci,hostfwd=tcp::10022-:22 @end example To connect to the VM you can run @example ssh -o UserKnownHostsFile=/dev/null -o StrictHostKeyChecking=no -p 10022 @end example The @command{-p} tells @command{ssh} the port you want to connect to. @command{-o UserKnownHostsFile=/dev/null} prevents @command{ssh} from complaining every time you modify your @command{config.scm} file and the @command{-o StrictHostKeyChecking=no} prevents you from having to allow a connection to an unknown host every time you connect. @subsection Using @command{virt-viewer} with Spice As an alternative to the default @command{qemu} graphical client you can use the @command{remote-viewer} from the @command{virt-viewer} package. To connect pass the @command{-spice port=5930,disable-ticketing} flag to @command{qemu}. See previous section for further information on how to do this. Spice also allows you to do some nice stuff like share your clipboard with your VM. To enable that you'll also have to pass the following flags to @command{qemu}: @example -device virtio-serial-pci,id=virtio-serial0,max_ports=16,bus=pci.0,addr=0x5 -chardev spicevmc,name=vdagent,id=vdagent -device virtserialport,nr=1,bus=virtio-serial0.0,chardev=vdagent, name=com.redhat.spice.0 @end example You'll also need to add the @code{(spice-vdagent-service)} to your system definition (@pxref{Miscellaneous Services, Spice service}). @node Defining Services @section Defining Services The previous sections show the available services and how one can combine them in an @code{operating-system} declaration. But how do we define them in the first place? And what is a service anyway? @menu * Service Composition:: The model for composing services. * Service Types and Services:: Types and services. * Service Reference:: API reference. * Shepherd Services:: A particular type of service. @end menu @node Service Composition @subsection Service Composition @cindex services @cindex daemons Here we define a @dfn{service} as, broadly, something that extends the functionality of the operating system. Often a service is a process---a @dfn{daemon}---started when the system boots: a secure shell server, a Web server, the Guix build daemon, etc. Sometimes a service is a daemon whose execution can be triggered by another daemon---e.g., an FTP server started by @command{inetd} or a D-Bus service activated by @command{dbus-daemon}. Occasionally, a service does not map to a daemon. For instance, the ``account'' service collects user accounts and makes sure they exist when the system runs; the ``udev'' service collects device management rules and makes them available to the eudev daemon; the @file{/etc} service populates the @file{/etc} directory of the system. @cindex service extensions Guix system services are connected by @dfn{extensions}. For instance, the secure shell service @emph{extends} the Shepherd---the initialization system, running as PID@tie{}1---by giving it the command lines to start and stop the secure shell daemon (@pxref{Networking Services, @code{openssh-service-type}}); the UPower service extends the D-Bus service by passing it its @file{.service} specification, and extends the udev service by passing it device management rules (@pxref{Desktop Services, @code{upower-service}}); the Guix daemon service extends the Shepherd by passing it the command lines to start and stop the daemon, and extends the account service by passing it a list of required build user accounts (@pxref{Base Services}). All in all, services and their ``extends'' relations form a directed acyclic graph (DAG). If we represent services as boxes and extensions as arrows, a typical system might provide something like this: @image{images/service-graph,,5in,Typical service extension graph.} @cindex system service At the bottom, we see the @dfn{system service}, which produces the directory containing everything to run and boot the system, as returned by the @command{guix system build} command. @xref{Service Reference}, to learn about the other service types shown here. @xref{system-extension-graph, the @command{guix system extension-graph} command}, for information on how to generate this representation for a particular operating system definition. @cindex service types Technically, developers can define @dfn{service types} to express these relations. There can be any number of services of a given type on the system---for instance, a system running two instances of the GNU secure shell server (lsh) has two instances of @code{lsh-service-type}, with different parameters. The following section describes the programming interface for service types and services. @node Service Types and Services @subsection Service Types and Services A @dfn{service type} is a node in the DAG described above. Let us start with a simple example, the service type for the Guix build daemon (@pxref{Invoking guix-daemon}): @lisp (define guix-service-type (service-type (name 'guix) (extensions (list (service-extension shepherd-root-service-type guix-shepherd-service) (service-extension account-service-type guix-accounts) (service-extension activation-service-type guix-activation))) (default-value (guix-configuration)))) @end lisp @noindent It defines three things: @enumerate @item A name, whose sole purpose is to make inspection and debugging easier. @item A list of @dfn{service extensions}, where each extension designates the target service type and a procedure that, given the parameters of the service, returns a list of objects to extend the service of that type. Every service type has at least one service extension. The only exception is the @dfn{boot service type}, which is the ultimate service. @item Optionally, a default value for instances of this type. @end enumerate In this example, @code{guix-service-type} extends three services: @table @code @item shepherd-root-service-type The @code{guix-shepherd-service} procedure defines how the Shepherd service is extended. Namely, it returns a @code{} object that defines how @command{guix-daemon} is started and stopped (@pxref{Shepherd Services}). @item account-service-type This extension for this service is computed by @code{guix-accounts}, which returns a list of @code{user-group} and @code{user-account} objects representing the build user accounts (@pxref{Invoking guix-daemon}). @item activation-service-type Here @code{guix-activation} is a procedure that returns a gexp, which is a code snippet to run at ``activation time''---e.g., when the service is booted. @end table A service of this type is instantiated like this: @lisp (service guix-service-type (guix-configuration (build-accounts 5) (extra-options '("--gc-keep-derivations")))) @end lisp The second argument to the @code{service} form is a value representing the parameters of this specific service instance. @xref{guix-configuration-type, @code{guix-configuration}}, for information about the @code{guix-configuration} data type. When the value is omitted, the default value specified by @code{guix-service-type} is used: @lisp (service guix-service-type) @end lisp @code{guix-service-type} is quite simple because it extends other services but is not extensible itself. @c @subsubsubsection Extensible Service Types The service type for an @emph{extensible} service looks like this: @lisp (define udev-service-type (service-type (name 'udev) (extensions (list (service-extension shepherd-root-service-type udev-shepherd-service))) (compose concatenate) ;concatenate the list of rules (extend (lambda (config rules) (match config (($ udev initial-rules) (udev-configuration (udev udev) ;the udev package to use (rules (append initial-rules rules))))))))) @end lisp This is the service type for the @uref{https://wiki.gentoo.org/wiki/Project:Eudev, eudev device management daemon}. Compared to the previous example, in addition to an extension of @code{shepherd-root-service-type}, we see two new fields: @table @code @item compose This is the procedure to @dfn{compose} the list of extensions to services of this type. Services can extend the udev service by passing it lists of rules; we compose those extensions simply by concatenating them. @item extend This procedure defines how the value of the service is @dfn{extended} with the composition of the extensions. Udev extensions are composed into a list of rules, but the udev service value is itself a @code{} record. So here, we extend that record by appending the list of rules it contains to the list of contributed rules. @item description This is a string giving an overview of the service type. The string can contain Texinfo markup (@pxref{Overview,,, texinfo, GNU Texinfo}). The @command{guix system search} command searches these strings and displays them (@pxref{Invoking guix system}). @end table There can be only one instance of an extensible service type such as @code{udev-service-type}. If there were more, the @code{service-extension} specifications would be ambiguous. Still here? The next section provides a reference of the programming interface for services. @node Service Reference @subsection Service Reference We have seen an overview of service types (@pxref{Service Types and Services}). This section provides a reference on how to manipulate services and service types. This interface is provided by the @code{(gnu services)} module. @deffn {Scheme Procedure} service @var{type} [@var{value}] Return a new service of @var{type}, a @code{} object (see below). @var{value} can be any object; it represents the parameters of this particular service instance. When @var{value} is omitted, the default value specified by @var{type} is used; if @var{type} does not specify a default value, an error is raised. For instance, this: @lisp (service openssh-service-type) @end lisp @noindent is equivalent to this: @lisp (service openssh-service-type (openssh-configuration)) @end lisp In both cases the result is an instance of @code{openssh-service-type} with the default configuration. @end deffn @deffn {Scheme Procedure} service? @var{obj} Return true if @var{obj} is a service. @end deffn @deffn {Scheme Procedure} service-kind @var{service} Return the type of @var{service}---i.e., a @code{} object. @end deffn @deffn {Scheme Procedure} service-value @var{service} Return the value associated with @var{service}. It represents its parameters. @end deffn Here is an example of how a service is created and manipulated: @lisp (define s (service nginx-service-type (nginx-configuration (nginx nginx) (log-directory log-directory) (run-directory run-directory) (file config-file)))) (service? s) @result{} #t (eq? (service-kind s) nginx-service-type) @result{} #t @end lisp The @code{modify-services} form provides a handy way to change the parameters of some of the services of a list such as @code{%base-services} (@pxref{Base Services, @code{%base-services}}). It evaluates to a list of services. Of course, you could always use standard list combinators such as @code{map} and @code{fold} to do that (@pxref{SRFI-1, List Library,, guile, GNU Guile Reference Manual}); @code{modify-services} simply provides a more concise form for this common pattern. @deffn {Scheme Syntax} modify-services @var{services} @ (@var{type} @var{variable} => @var{body}) @dots{} Modify the services listed in @var{services} according to the given clauses. Each clause has the form: @example (@var{type} @var{variable} => @var{body}) @end example where @var{type} is a service type---e.g., @code{guix-service-type}---and @var{variable} is an identifier that is bound within the @var{body} to the service parameters---e.g., a @code{guix-configuration} instance---of the original service of that @var{type}. The @var{body} should evaluate to the new service parameters, which will be used to configure the new service. This new service will replace the original in the resulting list. Because a service's service parameters are created using @code{define-record-type*}, you can write a succinct @var{body} that evaluates to the new service parameters by using the @code{inherit} feature that @code{define-record-type*} provides. @xref{Using the Configuration System}, for example usage. @end deffn Next comes the programming interface for service types. This is something you want to know when writing new service definitions, but not necessarily when simply looking for ways to customize your @code{operating-system} declaration. @deftp {Data Type} service-type @cindex service type This is the representation of a @dfn{service type} (@pxref{Service Types and Services}). @table @asis @item @code{name} This is a symbol, used only to simplify inspection and debugging. @item @code{extensions} A non-empty list of @code{} objects (see below). @item @code{compose} (default: @code{#f}) If this is @code{#f}, then the service type denotes services that cannot be extended---i.e., services that do not receive ``values'' from other services. Otherwise, it must be a one-argument procedure. The procedure is called by @code{fold-services} and is passed a list of values collected from extensions. It may return any single value. @item @code{extend} (default: @code{#f}) If this is @code{#f}, services of this type cannot be extended. Otherwise, it must be a two-argument procedure: @code{fold-services} calls it, passing it the initial value of the service as the first argument and the result of applying @code{compose} to the extension values as the second argument. It must return a value that is a valid parameter value for the service instance. @item @code{description} This is a string, possibly using Texinfo markup, describing in a couple of sentences what the service is about. This string allows users to find about the service through @command{guix system search} (@pxref{Invoking guix system}). @item @code{default-value} (default: @code{&no-default-value}) The default value associated for instances of this service type. This allows users to use the @code{service} form without its second argument: @lisp (service @var{type}) @end lisp The returned service in this case has the default value specified by @var{type}. @end table @xref{Service Types and Services}, for examples. @end deftp @deffn {Scheme Procedure} service-extension @var{target-type} @ @var{compute} Return a new extension for services of type @var{target-type}. @var{compute} must be a one-argument procedure: @code{fold-services} calls it, passing it the value associated with the service that provides the extension; it must return a valid value for the target service. @end deffn @deffn {Scheme Procedure} service-extension? @var{obj} Return true if @var{obj} is a service extension. @end deffn Occasionally, you might want to simply extend an existing service. This involves creating a new service type and specifying the extension of interest, which can be verbose; the @code{simple-service} procedure provides a shorthand for this. @deffn {Scheme Procedure} simple-service @var{name} @var{target} @var{value} Return a service that extends @var{target} with @var{value}. This works by creating a singleton service type @var{name}, of which the returned service is an instance. For example, this extends mcron (@pxref{Scheduled Job Execution}) with an additional job: @lisp (simple-service 'my-mcron-job mcron-service-type #~(job '(next-hour (3)) "guix gc -F 2G")) @end lisp @end deffn At the core of the service abstraction lies the @code{fold-services} procedure, which is responsible for ``compiling'' a list of services down to a single directory that contains everything needed to boot and run the system---the directory shown by the @command{guix system build} command (@pxref{Invoking guix system}). In essence, it propagates service extensions down the service graph, updating each node parameters on the way, until it reaches the root node. @deffn {Scheme Procedure} fold-services @var{services} @ [#:target-type @var{system-service-type}] Fold @var{services} by propagating their extensions down to the root of type @var{target-type}; return the root service adjusted accordingly. @end deffn Lastly, the @code{(gnu services)} module also defines several essential service types, some of which are listed below. @defvr {Scheme Variable} system-service-type This is the root of the service graph. It produces the system directory as returned by the @command{guix system build} command. @end defvr @defvr {Scheme Variable} boot-service-type The type of the ``boot service'', which produces the @dfn{boot script}. The boot script is what the initial RAM disk runs when booting. @end defvr @defvr {Scheme Variable} etc-service-type The type of the @file{/etc} service. This service is used to create files under @file{/etc} and can be extended by passing it name/file tuples such as: @lisp (list `("issue" ,(plain-file "issue" "Welcome!\n"))) @end lisp In this example, the effect would be to add an @file{/etc/issue} file pointing to the given file. @end defvr @defvr {Scheme Variable} setuid-program-service-type Type for the ``setuid-program service''. This service collects lists of executable file names, passed as gexps, and adds them to the set of setuid-root programs on the system (@pxref{Setuid Programs}). @end defvr @defvr {Scheme Variable} profile-service-type Type of the service that populates the @dfn{system profile}---i.e., the programs under @file{/run/current-system/profile}. Other services can extend it by passing it lists of packages to add to the system profile. @end defvr @cindex provenance tracking, of the operating system @anchor{provenance-service-type} @defvr {Scheme Variable} provenance-service-type This is the type of the service that records @dfn{provenance meta-data} in the system itself. It creates several files under @file{/run/current-system}: @table @file @item channels.scm This is a ``channel file'' that can be passed to @command{guix pull -C} or @command{guix time-machine -C}, and which describes the channels used to build the system, if that information was available (@pxref{Channels}). @item configuration.scm This is the file that was passed as the value for this @code{provenance-service-type} service. By default, @command{guix system reconfigure} automatically passes the OS configuration file it received on the command line. @item provenance This contains the same information as the two other files but in a format that is more readily processable. @end table In general, these two pieces of information (channels and configuration file) are enough to reproduce the operating system ``from source''. @quotation Caveats This information is necessary to rebuild your operating system, but it is not always sufficient. In particular, @file{configuration.scm} itself is insufficient if it is not self-contained---if it refers to external Guile modules or to extra files. If you want @file{configuration.scm} to be self-contained, we recommend that modules or files it refers to be part of a channel. Besides, provenance meta-data is ``silent'' in the sense that it does not change the bits contained in your system, @emph{except for the meta-data bits themselves}. Two different OS configurations or sets of channels can lead to the same system, bit-for-bit; when @code{provenance-service-type} is used, these two systems will have different meta-data and thus different store file names, which makes comparison less trivial. @end quotation This service is automatically added to your operating system configuration when you use @command{guix system reconfigure}, @command{guix system init}, or @command{guix deploy}. @end defvr @node Shepherd Services @subsection Shepherd Services @cindex shepherd services @cindex PID 1 @cindex init system The @code{(gnu services shepherd)} module provides a way to define services managed by the GNU@tie{}Shepherd, which is the initialization system---the first process that is started when the system boots, also known as PID@tie{}1 (@pxref{Introduction,,, shepherd, The GNU Shepherd Manual}). Services in the Shepherd can depend on each other. For instance, the SSH daemon may need to be started after the syslog daemon has been started, which in turn can only happen once all the file systems have been mounted. The simple operating system defined earlier (@pxref{Using the Configuration System}) results in a service graph like this: @image{images/shepherd-graph,,5in,Typical shepherd service graph.} You can actually generate such a graph for any operating system definition using the @command{guix system shepherd-graph} command (@pxref{system-shepherd-graph, @command{guix system shepherd-graph}}). The @code{%shepherd-root-service} is a service object representing PID@tie{}1, of type @code{shepherd-root-service-type}; it can be extended by passing it lists of @code{} objects. @deftp {Data Type} shepherd-service The data type representing a service managed by the Shepherd. @table @asis @item @code{provision} This is a list of symbols denoting what the service provides. These are the names that may be passed to @command{herd start}, @command{herd status}, and similar commands (@pxref{Invoking herd,,, shepherd, The GNU Shepherd Manual}). @xref{Slots of services, the @code{provides} slot,, shepherd, The GNU Shepherd Manual}, for details. @item @code{requirement} (default: @code{'()}) List of symbols denoting the Shepherd services this one depends on. @cindex one-shot services, for the Shepherd @item @code{one-shot?} (default: @code{#f}) Whether this service is @dfn{one-shot}. One-shot services stop immediately after their @code{start} action has completed. @xref{Slots of services,,, shepherd, The GNU Shepherd Manual}, for more info. @item @code{respawn?} (default: @code{#t}) Whether to restart the service when it stops, for instance when the underlying process dies. @item @code{start} @itemx @code{stop} (default: @code{#~(const #f)}) The @code{start} and @code{stop} fields refer to the Shepherd's facilities to start and stop processes (@pxref{Service De- and Constructors,,, shepherd, The GNU Shepherd Manual}). They are given as G-expressions that get expanded in the Shepherd configuration file (@pxref{G-Expressions}). @item @code{actions} (default: @code{'()}) @cindex actions, of Shepherd services This is a list of @code{shepherd-action} objects (see below) defining @dfn{actions} supported by the service, in addition to the standard @code{start} and @code{stop} actions. Actions listed here become available as @command{herd} sub-commands: @example herd @var{action} @var{service} [@var{arguments}@dots{}] @end example @item @code{auto-start?} (default: @code{#t}) Whether this service should be started automatically by the Shepherd. If it is @code{#f} the service has to be started manually with @code{herd start}. @item @code{documentation} A documentation string, as shown when running: @example herd doc @var{service-name} @end example where @var{service-name} is one of the symbols in @code{provision} (@pxref{Invoking herd,,, shepherd, The GNU Shepherd Manual}). @item @code{modules} (default: @code{%default-modules}) This is the list of modules that must be in scope when @code{start} and @code{stop} are evaluated. @end table @end deftp @deftp {Data Type} shepherd-action This is the data type that defines additional actions implemented by a Shepherd service (see above). @table @code @item name Symbol naming the action. @item documentation This is a documentation string for the action. It can be viewed by running: @example herd doc @var{service} action @var{action} @end example @item procedure This should be a gexp that evaluates to a procedure of at least one argument, which is the ``running value'' of the service (@pxref{Slots of services,,, shepherd, The GNU Shepherd Manual}). @end table The following example defines an action called @code{say-hello} that kindly greets the user: @lisp (shepherd-action (name 'say-hello) (documentation "Say hi!") (procedure #~(lambda (running . args) (format #t "Hello, friend! arguments: ~s\n" args) #t))) @end lisp Assuming this action is added to the @code{example} service, then you can do: @example # herd say-hello example Hello, friend! arguments: () # herd say-hello example a b c Hello, friend! arguments: ("a" "b" "c") @end example This, as you can see, is a fairly sophisticated way to say hello. @xref{Service Convenience,,, shepherd, The GNU Shepherd Manual}, for more info on actions. @end deftp @defvr {Scheme Variable} shepherd-root-service-type The service type for the Shepherd ``root service''---i.e., PID@tie{}1. This is the service type that extensions target when they want to create shepherd services (@pxref{Service Types and Services}, for an example). Each extension must pass a list of @code{}. @end defvr @defvr {Scheme Variable} %shepherd-root-service This service represents PID@tie{}1. @end defvr @node Documentation @chapter Documentation @cindex documentation, searching for @cindex searching for documentation @cindex Info, documentation format @cindex man pages @cindex manual pages In most cases packages installed with Guix come with documentation. There are two main documentation formats: ``Info'', a browseable hypertext format used for GNU software, and ``manual pages'' (or ``man pages''), the linear documentation format traditionally found on Unix. Info manuals are accessed with the @command{info} command or with Emacs, and man pages are accessed using @command{man}. You can look for documentation of software installed on your system by keyword. For example, the following command searches for information about ``TLS'' in Info manuals: @example $ info -k TLS "(emacs)Network Security" -- STARTTLS "(emacs)Network Security" -- TLS "(gnutls)Core TLS API" -- gnutls_certificate_set_verify_flags "(gnutls)Core TLS API" -- gnutls_certificate_set_verify_function @dots{} @end example @noindent The command below searches for the same keyword in man pages: @example $ man -k TLS SSL (7) - OpenSSL SSL/TLS library certtool (1) - GnuTLS certificate tool @dots {} @end example These searches are purely local to your computer so you have the guarantee that documentation you find corresponds to what you have actually installed, you can access it off-line, and your privacy is respected. Once you have these results, you can view the relevant documentation by running, say: @example $ info "(gnutls)Core TLS API" @end example @noindent or: @example $ man certtool @end example Info manuals contain sections and indices as well as hyperlinks like those found in Web pages. The @command{info} reader (@pxref{Top, Info reader,, info-stnd, Stand-alone GNU Info}) and its Emacs counterpart (@pxref{Misc Help,,, emacs, The GNU Emacs Manual}) provide intuitive key bindings to navigate manuals. @xref{Getting Started,,, info, Info: An Introduction}, for an introduction to Info navigation. @node Installing Debugging Files @chapter Installing Debugging Files @cindex debugging files Program binaries, as produced by the GCC compilers for instance, are typically written in the ELF format, with a section containing @dfn{debugging information}. Debugging information is what allows the debugger, GDB, to map binary code to source code; it is required to debug a compiled program in good conditions. This chapter explains how to use separate debug info when packages provide it, and how to rebuild packages with debug info when it's missing. @menu * Separate Debug Info:: Installing 'debug' outputs. * Rebuilding Debug Info:: Building missing debug info. @end menu @node Separate Debug Info @section Separate Debug Info The problem with debugging information is that is takes up a fair amount of disk space. For example, debugging information for the GNU C Library weighs in at more than 60 MiB. Thus, as a user, keeping all the debugging info of all the installed programs is usually not an option. Yet, space savings should not come at the cost of an impediment to debugging---especially in the GNU system, which should make it easier for users to exert their computing freedom (@pxref{GNU Distribution}). Thankfully, the GNU Binary Utilities (Binutils) and GDB provide a mechanism that allows users to get the best of both worlds: debugging information can be stripped from the binaries and stored in separate files. GDB is then able to load debugging information from those files, when they are available (@pxref{Separate Debug Files,,, gdb, Debugging with GDB}). The GNU distribution takes advantage of this by storing debugging information in the @code{lib/debug} sub-directory of a separate package output unimaginatively called @code{debug} (@pxref{Packages with Multiple Outputs}). Users can choose to install the @code{debug} output of a package when they need it. For instance, the following command installs the debugging information for the GNU C Library and for GNU Guile: @example guix install glibc:debug guile:debug @end example GDB must then be told to look for debug files in the user's profile, by setting the @code{debug-file-directory} variable (consider setting it from the @file{~/.gdbinit} file, @pxref{Startup,,, gdb, Debugging with GDB}): @example (gdb) set debug-file-directory ~/.guix-profile/lib/debug @end example From there on, GDB will pick up debugging information from the @file{.debug} files under @file{~/.guix-profile/lib/debug}. In addition, you will most likely want GDB to be able to show the source code being debugged. To do that, you will have to unpack the source code of the package of interest (obtained with @code{guix build --source}, @pxref{Invoking guix build}), and to point GDB to that source directory using the @code{directory} command (@pxref{Source Path, @code{directory},, gdb, Debugging with GDB}). @c XXX: keep me up-to-date The @code{debug} output mechanism in Guix is implemented by the @code{gnu-build-system} (@pxref{Build Systems}). Currently, it is opt-in---debugging information is available only for the packages with definitions explicitly declaring a @code{debug} output. To check whether a package has a @code{debug} output, use @command{guix package --list-available} (@pxref{Invoking guix package}). Read on for how to deal with packages lacking a @code{debug} output. @node Rebuilding Debug Info @section Rebuilding Debug Info @cindex debugging info, rebuilding As we saw above, some packages, but not all, provide debugging info in a @code{debug} output. What can you do when debugging info is missing? The @option{--with-debug-info} option provides a solution to that: it allows you to rebuild the package(s) for which debugging info is missing---and only those---and to graft those onto the application you're debugging. Thus, while it's not as fast as installing a @code{debug} output, it is relatively inexpensive. Let's illustrate that. Suppose you're experiencing a bug in Inkscape and would like to see what's going on in GLib, a library that's deep down in its dependency graph. As it turns out, GLib does not have a @code{debug} output and the backtrace GDB shows is all sadness: @example (gdb) bt #0 0x00007ffff5f92190 in g_getenv () from /gnu/store/@dots{}-glib-2.62.6/lib/libglib-2.0.so.0 #1 0x00007ffff608a7d6 in gobject_init_ctor () from /gnu/store/@dots{}-glib-2.62.6/lib/libgobject-2.0.so.0 #2 0x00007ffff7fe275a in call_init (l=, argc=argc@@entry=1, argv=argv@@entry=0x7fffffffcfd8, env=env@@entry=0x7fffffffcfe8) at dl-init.c:72 #3 0x00007ffff7fe2866 in call_init (env=0x7fffffffcfe8, argv=0x7fffffffcfd8, argc=1, l=) at dl-init.c:118 @end example To address that, you install Inkscape linked against a variant GLib that contains debug info: @example guix install inkscape --with-debug-info=glib @end example This time, debugging will be a whole lot nicer: @example $ gdb --args sh -c 'exec inkscape' @dots{} (gdb) b g_getenv Function "g_getenv" not defined. Make breakpoint pending on future shared library load? (y or [n]) y Breakpoint 1 (g_getenv) pending. (gdb) r Starting program: /gnu/store/@dots{}-profile/bin/sh -c exec\ inkscape @dots{} (gdb) bt #0 g_getenv (variable=variable@@entry=0x7ffff60c7a2e "GOBJECT_DEBUG") at ../glib-2.62.6/glib/genviron.c:252 #1 0x00007ffff608a7d6 in gobject_init () at ../glib-2.62.6/gobject/gtype.c:4380 #2 gobject_init_ctor () at ../glib-2.62.6/gobject/gtype.c:4493 #3 0x00007ffff7fe275a in call_init (l=, argc=argc@@entry=3, argv=argv@@entry=0x7fffffffd088, env=env@@entry=0x7fffffffd0a8) at dl-init.c:72 @dots{} @end example Much better! Note that there can be packages for which @option{--with-debug-info} will not have the desired effect. @xref{Package Transformation Options, @option{--with-debug-info}}, for more information. @node Security Updates @chapter Security Updates @cindex security updates @cindex security vulnerabilities Occasionally, important security vulnerabilities are discovered in software packages and must be patched. Guix developers try hard to keep track of known vulnerabilities and to apply fixes as soon as possible in the @code{master} branch of Guix (we do not yet provide a ``stable'' branch containing only security updates). The @command{guix lint} tool helps developers find out about vulnerable versions of software packages in the distribution: @smallexample $ guix lint -c cve gnu/packages/base.scm:652:2: glibc@@2.21: probably vulnerable to CVE-2015-1781, CVE-2015-7547 gnu/packages/gcc.scm:334:2: gcc@@4.9.3: probably vulnerable to CVE-2015-5276 gnu/packages/image.scm:312:2: openjpeg@@2.1.0: probably vulnerable to CVE-2016-1923, CVE-2016-1924 @dots{} @end smallexample @xref{Invoking guix lint}, for more information. Guix follows a functional package management discipline (@pxref{Introduction}), which implies that, when a package is changed, @emph{every package that depends on it} must be rebuilt. This can significantly slow down the deployment of fixes in core packages such as libc or Bash, since basically the whole distribution would need to be rebuilt. Using pre-built binaries helps (@pxref{Substitutes}), but deployment may still take more time than desired. @cindex grafts To address this, Guix implements @dfn{grafts}, a mechanism that allows for fast deployment of critical updates without the costs associated with a whole-distribution rebuild. The idea is to rebuild only the package that needs to be patched, and then to ``graft'' it onto packages explicitly installed by the user and that were previously referring to the original package. The cost of grafting is typically very low, and order of magnitudes lower than a full rebuild of the dependency chain. @cindex replacements of packages, for grafts For instance, suppose a security update needs to be applied to Bash. Guix developers will provide a package definition for the ``fixed'' Bash, say @code{bash-fixed}, in the usual way (@pxref{Defining Packages}). Then, the original package definition is augmented with a @code{replacement} field pointing to the package containing the bug fix: @lisp (define bash (package (name "bash") ;; @dots{} (replacement bash-fixed))) @end lisp From there on, any package depending directly or indirectly on Bash---as reported by @command{guix gc --requisites} (@pxref{Invoking guix gc})---that is installed is automatically ``rewritten'' to refer to @code{bash-fixed} instead of @code{bash}. This grafting process takes time proportional to the size of the package, usually less than a minute for an ``average'' package on a recent machine. Grafting is recursive: when an indirect dependency requires grafting, then grafting ``propagates'' up to the package that the user is installing. Currently, the length of the name and version of the graft and that of the package it replaces (@code{bash-fixed} and @code{bash} in the example above) must be equal. This restriction mostly comes from the fact that grafting works by patching files, including binary files, directly. Other restrictions may apply: for instance, when adding a graft to a package providing a shared library, the original shared library and its replacement must have the same @code{SONAME} and be binary-compatible. The @option{--no-grafts} command-line option allows you to forcefully avoid grafting (@pxref{Common Build Options, @option{--no-grafts}}). Thus, the command: @example guix build bash --no-grafts @end example @noindent returns the store file name of the original Bash, whereas: @example guix build bash @end example @noindent returns the store file name of the ``fixed'', replacement Bash. This allows you to distinguish between the two variants of Bash. To verify which Bash your whole profile refers to, you can run (@pxref{Invoking guix gc}): @example guix gc -R `readlink -f ~/.guix-profile` | grep bash @end example @noindent @dots{} and compare the store file names that you get with those above. Likewise for a complete Guix system generation: @example guix gc -R `guix system build my-config.scm` | grep bash @end example Lastly, to check which Bash running processes are using, you can use the @command{lsof} command: @example lsof | grep /gnu/store/.*bash @end example @node Bootstrapping @chapter Bootstrapping @c Adapted from the ELS 2013 paper. @cindex bootstrapping Bootstrapping in our context refers to how the distribution gets built ``from nothing''. Remember that the build environment of a derivation contains nothing but its declared inputs (@pxref{Introduction}). So there's an obvious chicken-and-egg problem: how does the first package get built? How does the first compiler get compiled? It is tempting to think of this question as one that only die-hard hackers may care about. However, while the answer to that question is technical in nature, its implications are wide-ranging. How the distribution is bootstrapped defines the extent to which we, as individuals and as a collective of users and hackers, can trust the software we run. It is a central concern from the standpoint of @emph{security} and from a @emph{user freedom} viewpoint. @cindex bootstrap binaries The GNU system is primarily made of C code, with libc at its core. The GNU build system itself assumes the availability of a Bourne shell and command-line tools provided by GNU Coreutils, Awk, Findutils, `sed', and `grep'. Furthermore, build programs---programs that run @code{./configure}, @code{make}, etc.---are written in Guile Scheme (@pxref{Derivations}). Consequently, to be able to build anything at all, from scratch, Guix relies on pre-built binaries of Guile, GCC, Binutils, libc, and the other packages mentioned above---the @dfn{bootstrap binaries}. These bootstrap binaries are ``taken for granted'', though we can also re-create them if needed (@pxref{Preparing to Use the Bootstrap Binaries}). @menu * Reduced Binary Seed Bootstrap:: A Bootstrap worthy of GNU. * Preparing to Use the Bootstrap Binaries:: Building that what matters most. @end menu @node Reduced Binary Seed Bootstrap @section The Reduced Binary Seed Bootstrap Guix---like other GNU/Linux distributions---is traditionally bootstrapped from a set of bootstrap binaries: Bourne shell, command-line tools provided by GNU Coreutils, Awk, Findutils, `sed', and `grep' and Guile, GCC, Binutils, and the GNU C Library (@pxref{Bootstrapping}). Usually, these bootstrap binaries are ``taken for granted.'' Taking the bootstrap binaries for granted means that we consider them to be a correct and trustworthy ``seed'' for building the complete system. Therein lies a problem: the combined size of these bootstrap binaries is about 250MB (@pxref{Bootstrappable Builds,,, mes, GNU Mes}). Auditing or even inspecting these is next to impossible. For @code{i686-linux} and @code{x86_64-linux}, Guix now features a ``Reduced Binary Seed'' bootstrap @footnote{We would like to say: ``Full Source Bootstrap'' and while we are working towards that goal it would be hyperbole to use that term for what we do now.}. The Reduced Binary Seed bootstrap removes the most critical tools---from a trust perspective---from the bootstrap binaries: GCC, Binutils and the GNU C Library are replaced by: @code{bootstrap-mescc-tools} (a tiny assembler and linker) and @code{bootstrap-mes} (a small Scheme Interpreter and a C compiler written in Scheme and the Mes C Library, built for TinyCC and for GCC). Using these new binary seeds the ``missing'' Binutils, GCC, and the GNU C Library are built from source. From here on the more traditional bootstrap process resumes. This approach has reduced the bootstrap binaries in size to about 145MB in Guix v1.1. The next step that Guix has taken is to replace the shell and all its utilities with implementations in Guile Scheme, the @emph{Scheme-only bootstrap}. Gash (@pxref{Gash,,, gash, The Gash manual}) is a POSIX-compatible shell that replaces Bash, and it comes with Gash Utils which has minimalist replacements for Awk, the GNU Core Utilities, Grep, Gzip, Sed, and Tar. The rest of the bootstrap binary seeds that were removed are now built from source. Building the GNU System from source is currently only possibly by adding some historical GNU packages as intermediate steps@footnote{Packages such as @code{gcc-2.95.3}, @code{binutils-2.14}, @code{glibc-2.2.5}, @code{gzip-1.2.4}, @code{tar-1.22}, and some others. For details, see @file{gnu/packages/commencement.scm}.}. As Gash and Gash Utils mature, and GNU packages become more bootstrappable again (e.g., new releases of GNU Sed will also ship as gzipped tarballs again, as alternative to the hard to bootstrap @code{xz}-compression), this set of added packages can hopefully be reduced again. The graph below shows the resulting dependency graph for @code{gcc-core-mesboot0}, the bootstrap compiler used for the traditional bootstrap of the rest of the Guix System. @c ./pre-inst-env guix graph -e '(@@ (gnu packages commencement) gcc-core-mesboot0)' | sed -re 's,((bootstrap-mescc-tools|bootstrap-mes|guile-bootstrap).*shape =) box,\1 ellipse,' > doc/images/gcc-core-mesboot0-graph.dot @image{images/gcc-core-mesboot0-graph,6in,,Dependency graph of gcc-core-mesboot0} The only significant binary bootstrap seeds that remain@footnote{ Ignoring the 68KB @code{mescc-tools}; that will be removed later, together with @code{mes}.} are a Scheme intepreter and a Scheme compiler: GNU Mes and GNU Guile@footnote{Not shown in this graph are the static binaries for @file{bash}, @code{tar}, and @code{xz} that are used to get Guile running.}. This further reduction has brought down the size of the binary seed to about 60MB for @code{i686-linux} and @code{x86_64-linux}. Work is ongoing to remove all binary blobs from our free software bootstrap stack, working towards a Full Source Bootstrap. Also ongoing is work to bring these bootstraps to the @code{arm-linux} and @code{aarch64-linux} architectures and to the Hurd. If you are interested, join us on @samp{#bootstrappable} on the Freenode IRC network or discuss on @email{bug-mes@@gnu.org} or @email{gash-devel@@nongnu.org}. @node Preparing to Use the Bootstrap Binaries @section Preparing to Use the Bootstrap Binaries @c As of Emacs 24.3, Info-mode displays the image, but since it's a @c large image, it's hard to scroll. Oh well. @image{images/bootstrap-graph,6in,,Dependency graph of the early bootstrap derivations} The figure above shows the very beginning of the dependency graph of the distribution, corresponding to the package definitions of the @code{(gnu packages bootstrap)} module. A similar figure can be generated with @command{guix graph} (@pxref{Invoking guix graph}), along the lines of: @example guix graph -t derivation \ -e '(@@@@ (gnu packages bootstrap) %bootstrap-gcc)' \ | dot -Tps > gcc.ps @end example or, for the further Reduced Binary Seed bootstrap @example guix graph -t derivation \ -e '(@@@@ (gnu packages bootstrap) %bootstrap-mes)' \ | dot -Tps > mes.ps @end example At this level of detail, things are slightly complex. First, Guile itself consists of an ELF executable, along with many source and compiled Scheme files that are dynamically loaded when it runs. This gets stored in the @file{guile-2.0.7.tar.xz} tarball shown in this graph. This tarball is part of Guix's ``source'' distribution, and gets inserted into the store with @code{add-to-store} (@pxref{The Store}). But how do we write a derivation that unpacks this tarball and adds it to the store? To solve this problem, the @code{guile-bootstrap-2.0.drv} derivation---the first one that gets built---uses @code{bash} as its builder, which runs @code{build-bootstrap-guile.sh}, which in turn calls @code{tar} to unpack the tarball. Thus, @file{bash}, @file{tar}, @file{xz}, and @file{mkdir} are statically-linked binaries, also part of the Guix source distribution, whose sole purpose is to allow the Guile tarball to be unpacked. Once @code{guile-bootstrap-2.0.drv} is built, we have a functioning Guile that can be used to run subsequent build programs. Its first task is to download tarballs containing the other pre-built binaries---this is what the @file{.tar.xz.drv} derivations do. Guix modules such as @code{ftp-client.scm} are used for this purpose. The @code{module-import.drv} derivations import those modules in a directory in the store, using the original layout. The @code{module-import-compiled.drv} derivations compile those modules, and write them in an output directory with the right layout. This corresponds to the @code{#:modules} argument of @code{build-expression->derivation} (@pxref{Derivations}). Finally, the various tarballs are unpacked by the derivations @code{gcc-bootstrap-0.drv}, @code{glibc-bootstrap-0.drv}, or @code{bootstrap-mes-0.drv} and @code{bootstrap-mescc-tools-0.drv}, at which point we have a working C tool chain. @unnumberedsec Building the Build Tools Bootstrapping is complete when we have a full tool chain that does not depend on the pre-built bootstrap tools discussed above. This no-dependency requirement is verified by checking whether the files of the final tool chain contain references to the @file{/gnu/store} directories of the bootstrap inputs. The process that leads to this ``final'' tool chain is described by the package definitions found in the @code{(gnu packages commencement)} module. The @command{guix graph} command allows us to ``zoom out'' compared to the graph above, by looking at the level of package objects instead of individual derivations---remember that a package may translate to several derivations, typically one derivation to download its source, one to build the Guile modules it needs, and one to actually build the package from source. The command: @example guix graph -t bag \ -e '(@@@@ (gnu packages commencement) glibc-final-with-bootstrap-bash)' | xdot - @end example @noindent displays the dependency graph leading to the ``final'' C library@footnote{You may notice the @code{glibc-intermediate} label, suggesting that it is not @emph{quite} final, but as a good approximation, we will consider it final.}, depicted below. @image{images/bootstrap-packages,6in,,Dependency graph of the early packages} @c See . The first tool that gets built with the bootstrap binaries is GNU@tie{}Make---noted @code{make-boot0} above---which is a prerequisite for all the following packages. From there Findutils and Diffutils get built. Then come the first-stage Binutils and GCC, built as pseudo cross tools---i.e., with @option{--target} equal to @option{--host}. They are used to build libc. Thanks to this cross-build trick, this libc is guaranteed not to hold any reference to the initial tool chain. From there the final Binutils and GCC (not shown above) are built. GCC uses @command{ld} from the final Binutils, and links programs against the just-built libc. This tool chain is used to build the other packages used by Guix and by the GNU Build System: Guile, Bash, Coreutils, etc. And voilà! At this point we have the complete set of build tools that the GNU Build System expects. These are in the @code{%final-inputs} variable of the @code{(gnu packages commencement)} module, and are implicitly used by any package that uses @code{gnu-build-system} (@pxref{Build Systems, @code{gnu-build-system}}). @unnumberedsec Building the Bootstrap Binaries @cindex bootstrap binaries Because the final tool chain does not depend on the bootstrap binaries, those rarely need to be updated. Nevertheless, it is useful to have an automated way to produce them, should an update occur, and this is what the @code{(gnu packages make-bootstrap)} module provides. The following command builds the tarballs containing the bootstrap binaries (Binutils, GCC, glibc, for the traditional bootstrap and linux-libre-headers, bootstrap-mescc-tools, bootstrap-mes for the Reduced Binary Seed bootstrap, and Guile, and a tarball containing a mixture of Coreutils and other basic command-line tools): @example guix build bootstrap-tarballs @end example The generated tarballs are those that should be referred to in the @code{(gnu packages bootstrap)} module mentioned at the beginning of this section. Still here? Then perhaps by now you've started to wonder: when do we reach a fixed point? That is an interesting question! The answer is unknown, but if you would like to investigate further (and have significant computational and storage resources to do so), then let us know. @unnumberedsec Reducing the Set of Bootstrap Binaries Our traditional bootstrap includes GCC, GNU Libc, Guile, etc. That's a lot of binary code! Why is that a problem? It's a problem because these big chunks of binary code are practically non-auditable, which makes it hard to establish what source code produced them. Every unauditable binary also leaves us vulnerable to compiler backdoors as described by Ken Thompson in the 1984 paper @emph{Reflections on Trusting Trust}. This is mitigated by the fact that our bootstrap binaries were generated from an earlier Guix revision. Nevertheless it lacks the level of transparency that we get in the rest of the package dependency graph, where Guix always gives us a source-to-binary mapping. Thus, our goal is to reduce the set of bootstrap binaries to the bare minimum. The @uref{https://bootstrappable.org, Bootstrappable.org web site} lists on-going projects to do that. One of these is about replacing the bootstrap GCC with a sequence of assemblers, interpreters, and compilers of increasing complexity, which could be built from source starting from a simple and auditable assembler. Our first major achievement is the replacement of of GCC, the GNU C Library and Binutils by MesCC-Tools (a simple hex linker and macro assembler) and Mes (@pxref{Top, GNU Mes Reference Manual,, mes, GNU Mes}, a Scheme interpreter and C compiler in Scheme). Neither MesCC-Tools nor Mes can be fully bootstrapped yet and thus we inject them as binary seeds. We call this the Reduced Binary Seed bootstrap, as it has halved the size of our bootstrap binaries! Also, it has eliminated the C compiler binary; i686-linux and x86_64-linux Guix packages are now bootstrapped without any binary C compiler. Work is ongoing to make MesCC-Tools and Mes fully bootstrappable and we are also looking at any other bootstrap binaries. Your help is welcome! @node Porting @chapter Porting to a New Platform As discussed above, the GNU distribution is self-contained, and self-containment is achieved by relying on pre-built ``bootstrap binaries'' (@pxref{Bootstrapping}). These binaries are specific to an operating system kernel, CPU architecture, and application binary interface (ABI). Thus, to port the distribution to a platform that is not yet supported, one must build those bootstrap binaries, and update the @code{(gnu packages bootstrap)} module to use them on that platform. Fortunately, Guix can @emph{cross compile} those bootstrap binaries. When everything goes well, and assuming the GNU tool chain supports the target platform, this can be as simple as running a command like this one: @example guix build --target=armv5tel-linux-gnueabi bootstrap-tarballs @end example For this to work, the @code{glibc-dynamic-linker} procedure in @code{(gnu packages bootstrap)} must be augmented to return the right file name for libc's dynamic linker on that platform; likewise, @code{system->linux-architecture} in @code{(gnu packages linux)} must be taught about the new platform. Once these are built, the @code{(gnu packages bootstrap)} module needs to be updated to refer to these binaries on the target platform. That is, the hashes and URLs of the bootstrap tarballs for the new platform must be added alongside those of the currently supported platforms. The bootstrap Guile tarball is treated specially: it is expected to be available locally, and @file{gnu/local.mk} has rules to download it for the supported architectures; a rule for the new platform must be added as well. In practice, there may be some complications. First, it may be that the extended GNU triplet that specifies an ABI (like the @code{eabi} suffix above) is not recognized by all the GNU tools. Typically, glibc recognizes some of these, whereas GCC uses an extra @option{--with-abi} configure flag (see @code{gcc.scm} for examples of how to handle this). Second, some of the required packages could fail to build for that platform. Lastly, the generated binaries could be broken for some reason. @c ********************************************************************* @include contributing.texi @c ********************************************************************* @node Acknowledgments @chapter Acknowledgments Guix is based on the @uref{https://nixos.org/nix/, Nix package manager}, which was designed and implemented by Eelco Dolstra, with contributions from other people (see the @file{nix/AUTHORS} file in Guix). Nix pioneered functional package management, and promoted unprecedented features, such as transactional package upgrades and rollbacks, per-user profiles, and referentially transparent build processes. Without this work, Guix would not exist. The Nix-based software distributions, Nixpkgs and NixOS, have also been an inspiration for Guix. GNU@tie{}Guix itself is a collective work with contributions from a number of people. See the @file{AUTHORS} file in Guix for more information on these fine people. The @file{THANKS} file lists people who have helped by reporting bugs, taking care of the infrastructure, providing artwork and themes, making suggestions, and more---thank you! @c ********************************************************************* @node GNU Free Documentation License @appendix GNU Free Documentation License @cindex license, GNU Free Documentation License @include fdl-1.3.texi @c ********************************************************************* @node Concept Index @unnumbered Concept Index @printindex cp @node Programming Index @unnumbered Programming Index @syncodeindex tp fn @syncodeindex vr fn @printindex fn @bye @c Local Variables: @c ispell-local-dictionary: "american"; @c End: