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authorLudovic Courtès <ludo@gnu.org>2018-07-11 23:17:37 +0200
committerLudovic Courtès <ludo@gnu.org>2018-07-13 00:08:54 +0200
commit701383081a9814d21823d42978ae23ee654e0427 (patch)
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parent814bb8166804cc3c1f0dd1f1347786a1f07bd22b (diff)
downloadpatches-701383081a9814d21823d42978ae23ee654e0427.tar
patches-701383081a9814d21823d42978ae23ee654e0427.tar.gz
services: shepherd: Support custom actions.
* gnu/services/shepherd.scm (<shepherd-service>)[actions]: New field. (<shepherd-action>): New record type. (shepherd-service-file): Pass #:actions to 'make'. * doc/guix.texi (Shepherd Services): Document custom actions.
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diff --git a/doc/guix.texi b/doc/guix.texi
index 8b286e9d8e..34012a357b 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -21969,6 +21969,17 @@ 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{documentation}
A documentation string, as shown when running:
@@ -21986,6 +21997,54 @@ This is the list of modules that must be in scope when @code{start} and
@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:
+
+@example
+(shepherd-action
+ (name 'say-hello)
+ (documentation "Say hi!")
+ (procedure #~(lambda (running . args)
+ (format #t "Hello, friend! arguments: ~s\n"
+ args)
+ #t)))
+@end example
+
+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.