home: services: ssh: Add 'match-criteria' option.

* gnu/home/services/ssh.scm (serialize-address-family): Raise
'&formatted-message' instead of '&error'.
(ssh-match-keywords): New variable.
(match-criteria?): New procedure.
(match-criteria): New maybe type.
(openssh-host)[name]: Turn into 'maybe-string'.
[match-criteria]: New field.
(serialize-openssh-host): Adjust accordingly.
* doc/guix.texi (Secure Shell): Document it.

Signed-off-by: Ludovic Courtès <ludo@gnu.org>

1 files changed, 11 insertions, 1 deletions

diff --git a/doc/guix.texi b/doc/guix.texi
index a71751142b..395fc25818 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -43100,11 +43100,21 @@ Available @code{openssh-host} fields are:
 
 @table @asis
 @item @code{name} (type: string)
-Name of this host declaration.
+Name of this host declaration.  A @code{openssh-host} must define only
+@code{name} or @code{match-criteria}.  Use host-name @code{\"*\"} for
+top-level options.
 
 @item @code{host-name} (type: maybe-string)
 Host name---e.g., @code{"foo.example.org"} or @code{"192.168.1.2"}.
 
+@item @code{match-criteria} (type: maybe-match-criteria)
+When specified, this string denotes the set of hosts to which the entry
+applies, superseding the @code{host-name} field.  Its first element must be
+all or one of @code{ssh-match-keywords}.  The rest of the elements are
+arguments for the keyword, or other criteria.  A @code{openssh-host} must
+define only @code{name} or @code{match-criteria}.  Other host configuration
+options will apply to all hosts matching @code{match-criteria}.
+
 @item @code{address-family} (type: maybe-address-family)
 Address family to use when connecting to this host: one of
 @code{AF_INET} (for IPv4 only), @code{AF_INET6} (for IPv6 only).