services: guix: Add nar-herder-service-type.

* gnu/services/guix.scm (<nar-herder-configuration>): New record type.
(nar-herder-configuration, nar-herder-configuration?,
nar-herder-configuration-package,
nar-herder-configuration-user,
nar-herder-configuration-group,
nar-herder-configuration-mirror
nar-herder-configuration-database
nar-herder-configuration-database-dump
nar-herder-configuration-host
nar-herder-configuration-port
nar-herder-configuration-storage
nar-herder-configuration-storage-limit
nar-herder-configuration-storage-nar-removal-criteria
nar-herder-shepherd-services, nar-herder-activation,
nar-herder-account): New procedures.
(nar-herder-service-type): New variable.
* gnu/tests/guix.scm (%test-nar-herder): New variable.
* doc/guix.texi (Guix Services): Document the new service.

3 files changed, 298 insertions, 4 deletions

diff --git a/doc/guix.texi b/doc/guix.texi
index 94f8e5e481..c3f36d37ff 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -33637,6 +33637,78 @@ Extra command line options for @code{guix-data-service-process-jobs}.
 @end table
 @end deftp
 
+@subsubheading Nar Herder
+The @uref{https://git.cbaines.net/guix/nar-herder/about/,Nar Herder} is
+a utility for managing a collection of nars.
+
+@defvar {Scheme Variable} nar-herder-type
+Service type for the Guix Data Service.  Its value must be a
+@code{nar-herder-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} nar-herder-configuration
+Data type representing the configuration of the Guix Data Service.
+
+@table @asis
+@item @code{package} (default: @code{nar-herder})
+The Nar Herder package to use.
+
+@item @code{user} (default: @code{"nar-herder"})
+The system user to run the service as.
+
+@item @code{group} (default: @code{"nar-herder"})
+The system group to run the service as.
+
+@item @code{port} (default: @code{8734})
+The port to bind the server to.
+
+@item @code{host} (default: @code{"127.0.0.1"})
+The host to bind the server to.
+
+@item @code{mirror} (default: @code{#f})
+Optional URL of the other Nar Herder instance which should be mirrored.
+This means that this Nar Herder instance will download it's database,
+and keep it up to date.
+
+@item @code{database} (default: @code{"/var/lib/nar-herder/nar_herder.db"})
+Location for the database.  If this Nar Herder instance is mirroring
+another, the database will be downloaded if it doesn't exist.  If this
+Nar Herder instance isn't mirroring another, an empty database will be
+created.
+
+@item @code{database-dump} (default: @code{"/var/lib/nar-herder/nar_herder_dump.db"})
+Location of the database dump.  This is created and regularly updated by
+taking a copy of the database.  This is the version of the database that
+is available to download.
+
+@item @code{storage} (default: @code{#f})
+Optional location in which to store nars.
+
+@item @code{storage-limit} (default: @code{"none"})
+Limit in bytes for the nars stored in the storage location.  This can
+also be set to ``none'' so that there is no limit.
+
+When the storage location exceeds this size, nars are removed according
+to the nar removal criteria.
+
+@item @code{storage-nar-removal-criteria} (default: @code{'()})
+Criteria used to remove nars from the storage location.  These are used
+in conjunction with the storage limit.
+
+When the storage location exceeds the storage limit size, nars will be
+checked against the nar removal criteria and if any of the criteria
+match, they will be removed.  This will continue until the storage
+location is below the storage limit size.
+
+Each criteria is specified by a string, then an equals sign, then
+another string. Currently, only one criteria is supported, checking if a
+nar is stored on another Nar Herder instance.
+
+@end table
+@end deftp
+
 @node Linux Services
 @subsection Linux Services
 
diff --git a/gnu/services/guix.scm b/gnu/services/guix.scm
index df5fa13bea..6a5b276b33 100644
--- a/gnu/services/guix.scm
+++ b/gnu/services/guix.scm
@@ -1,5 +1,5 @@
 ;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2019 Christopher Baines <mail@cbaines.net>
+;;; Copyright © 2019, 2020, 2021, 2022 Christopher Baines <mail@cbaines.net>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -107,7 +107,22 @@
             guix-data-service-getmail-idle-mailboxes
             guix-data-service-commits-getmail-retriever-configuration
 
-            guix-data-service-type))
+            guix-data-service-type
+
+            nar-herder-service-type
+            nar-herder-configuration
+            nar-herder-configuration?
+            nar-herder-configuration-package
+            nar-herder-configuration-user
+            nar-herder-configuration-group
+            nar-herder-configuration-mirror
+            nar-herder-configuration-database
+            nar-herder-configuration-database-dump
+            nar-herder-configuration-host
+            nar-herder-configuration-port
+            nar-herder-configuration-storage
+            nar-herder-configuration-storage-limit
+            nar-herder-configuration-storage-nar-removal-criteria))
 
 ;;;; Commentary:
 ;;;
@@ -728,3 +743,133 @@ ca-certificates.crt file in the system profile."
      (guix-data-service-configuration))
    (description
     "Run an instance of the Guix Data Service.")))
+
+
+;;;
+;;; Nar Herder
+;;;
+
+(define-record-type* <nar-herder-configuration>
+  nar-herder-configuration make-nar-herder-configuration
+  nar-herder-configuration?
+  (package       nar-herder-configuration-package
+                 (default nar-herder))
+  (user          nar-herder-configuration-user
+                 (default "nar-herder"))
+  (group         nar-herder-configuration-group
+                 (default "nar-herder"))
+  (mirror        nar-herder-configuration-mirror
+                 (default #f))
+  (database      nar-herder-configuration-database
+                 (default "/var/lib/nar-herder/nar_herder.db"))
+  (database-dump nar-herder-configuration-database-dump
+                 (default "/var/lib/nar-herder/nar_herder_dump.db"))
+  (host          nar-herder-configuration-host
+                 (default "127.0.0.1"))
+  (port          nar-herder-configuration-port
+                 (default 8734))
+  (storage       nar-herder-configuration-storage
+                 (default #f))
+  (storage-limit nar-herder-configuration-storage-limit
+                 (default "none"))
+  (storage-nar-removal-criteria
+   nar-herder-configuration-storage-nar-removal-criteria
+   (default '())))
+
+(define (nar-herder-shepherd-services config)
+  (match-record config <nar-herder-configuration>
+    (package user group
+             mirror
+             database database-dump
+             host port
+             storage storage-limit storage-nar-removal-criteria)
+
+    (unless (or mirror storage)
+      (error "nar-herder: mirror or storage must be set"))
+
+    (list
+     (shepherd-service
+      (documentation "Nar Herder")
+      (provision '(nar-herder))
+      (requirement '(networking))
+      (start #~(make-forkexec-constructor
+                (list #$(file-append package
+                                     "/bin/nar-herder")
+                      "run-server"
+                      "--pid-file=/var/run/nar-herder/pid"
+                      #$(string-append "--port=" (number->string port))
+                      #$(string-append "--host=" host)
+                      #$@(if mirror
+                             (list (string-append "--mirror=" mirror))
+                             '())
+                      #$(string-append "--database=" database)
+                      #$(string-append "--database-dump=" database-dump)
+                      #$@(if storage
+                             (list (string-append "--storage=" storage))
+                             '())
+                      #$(string-append "--storage-limit="
+                                       (if (number? storage-limit)
+                                           (number->string storage-limit)
+                                           storage-limit))
+                      #$@(map (lambda (criteria)
+                                (string-append
+                                 "--storage-nar-removal-criteria="
+                                 (match criteria
+                                   ((k . v) (simple-format #f "~A=~A" k v))
+                                   (str str))))
+                              storage-nar-removal-criteria))
+                #:user #$user
+                #:group #$group
+                #:pid-file "/var/run/nar-herder/pid"
+                #:environment-variables
+                `(,(string-append
+                    "GUIX_LOCPATH=" #$glibc-utf8-locales "/lib/locale")
+                  "LC_ALL=en_US.utf8")
+                #:log-file "/var/log/nar-herder/server.log"))
+      (stop #~(make-kill-destructor))))))
+
+(define (nar-herder-activation config)
+  #~(begin
+      (use-modules (guix build utils))
+
+      (define %user
+        (getpw #$(nar-herder-configuration-user
+                  config)))
+
+      (chmod "/var/lib/nar-herder" #o755)
+
+      (mkdir-p "/var/log/nar-herder")
+
+      ;; Allow writing the PID file
+      (mkdir-p "/var/run/nar-herder")
+      (chown "/var/run/nar-herder"
+             (passwd:uid %user)
+             (passwd:gid %user))))
+
+(define (nar-herder-account config)
+  (match-record config <nar-herder-configuration>
+    (user group)
+    (list (user-group
+           (name group)
+           (system? #t))
+          (user-account
+           (name user)
+           (group group)
+           (system? #t)
+           (comment "Nar Herder user")
+           (home-directory "/var/lib/nar-herder")
+           (shell (file-append shadow "/sbin/nologin"))))))
+
+(define nar-herder-service-type
+  (service-type
+   (name 'nar-herder)
+   (extensions
+    (list
+     (service-extension shepherd-root-service-type
+                        nar-herder-shepherd-services)
+     (service-extension activation-service-type
+                        nar-herder-activation)
+     (service-extension account-service-type
+                        nar-herder-account)))
+   (description
+    "Run a Nar Herder server.")))
diff --git a/gnu/tests/guix.scm b/gnu/tests/guix.scm
index 69cac7c1aa..a4c3e35e5d 100644
--- a/gnu/tests/guix.scm
+++ b/gnu/tests/guix.scm
@@ -1,5 +1,5 @@
 ;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2019 Christopher Baines <mail@cbaines.net>
+;;; Copyright © 2019, 2020, 2021, 2022 Christopher Baines <mail@cbaines.net>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -36,7 +36,8 @@
   #:use-module (guix utils)
   #:use-module (ice-9 match)
   #:export (%test-guix-build-coordinator
-            %test-guix-data-service))
+            %test-guix-data-service
+            %test-nar-herder))
 
 ;;;
 ;;; Guix Build Coordinator
@@ -239,3 +240,79 @@ host	all	all	::1/128 	trust"))))))
    (name "guix-data-service")
    (description "Connect to a running Guix Data Service.")
    (value (run-guix-data-service-test))))
+
+
+;;;
+;;; Nar Herder
+;;;
+
+(define %nar-herder-os
+  (simple-operating-system
+   (service dhcp-client-service-type)
+   (service nar-herder-service-type
+            (nar-herder-configuration
+             (host "0.0.0.0")
+             ;; Not a realistic value, but works for the test
+             (storage "/tmp")))))
+
+(define (run-nar-herder-test)
+  (define os
+    (marionette-operating-system
+     %nar-herder-os
+     #:imported-modules '((gnu services herd)
+                          (guix combinators))))
+
+  (define forwarded-port
+    (nar-herder-configuration-port
+     (nar-herder-configuration)))
+
+  (define vm
+    (virtual-machine
+     (operating-system os)
+     (memory-size 1024)
+     (port-forwardings `((,forwarded-port . ,forwarded-port)))))
+
+  (define test
+    (with-imported-modules '((gnu build marionette))
+      #~(begin
+          (use-modules (srfi srfi-11) (srfi srfi-64)
+                       (gnu build marionette)
+                       (web uri)
+                       (web client)
+                       (web response))
+
+          (define marionette
+            (make-marionette (list #$vm)))
+
+          (test-runner-current (system-test-runner #$output))
+          (test-begin "nar-herder")
+
+          (test-assert "service running"
+            (marionette-eval
+             '(begin
+                (use-modules (gnu services herd))
+                (match (start-service 'nar-herder)
+                  (#f #f)
+                  (('service response-parts ...)
+                   (match (assq-ref response-parts 'running)
+                     ((pid) (number? pid))))))
+             marionette))
+
+          (test-equal "http-get"
+            404
+            (let-values
+                (((response text)
+                  (http-get #$(simple-format
+                               #f "http://localhost:~A/" forwarded-port)
+                            #:decode-body? #t)))
+              (response-code response)))
+
+          (test-end))))
+
+  (gexp->derivation "nar-herder-test" test))
+
+(define %test-nar-herder
+  (system-test
+   (name "nar-herder")
+   (description "Connect to a running Nar Herder server.")
+   (value (run-nar-herder-test))))