services: Add more description fields.

* gnu/services.scm (simple-service): Add 'description' field.
* gnu/services/base.scm (udev-rules-service): Likewise.
* gnu/system/install.scm (configuration-template-service-type): Likewise.
* gnu/tests.scm (marionette-service-type): Likewise.

4 files changed, 13 insertions, 6 deletions

diff --git a/gnu/services.scm b/gnu/services.scm
index e3d4fcc2324..234ee372b85 100644
--- a/gnu/services.scm
+++ b/gnu/services.scm
@@ -292,7 +292,8 @@ for service of type '~a'")
 singleton service type NAME, of which the returned service is an instance."
   (let* ((extension (service-extension target identity))
          (type      (service-type (name name)
-                                  (extensions (list extension)))))
+                                  (extensions (list extension))
+                                  (description "This is a simple service."))))
     (service type value)))
 
 (define-syntax %modify-service
diff --git a/gnu/services/base.scm b/gnu/services/base.scm
index bcec8885875..3fb92e6da07 100644
--- a/gnu/services/base.scm
+++ b/gnu/services/base.scm
@@ -2191,7 +2191,8 @@ instance."
                              (service-extension
                               account-service-type account-extension)
                              (service-extension
-                              udev-service-type udev-extension))))))
+                              udev-service-type udev-extension)))
+                (description "This service adds udev rules."))))
     (service type #f)))
 
 (define (swap-space->shepherd-service-name space)
diff --git a/gnu/system/install.scm b/gnu/system/install.scm
index 073d7df1dbb..2fbf08f6760 100644
--- a/gnu/system/install.scm
+++ b/gnu/system/install.scm
@@ -1,5 +1,5 @@
 ;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2014, 2015, 2016, 2017, 2018, 2019, 2020, 2021 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2014-2022 Ludovic Courtès <ludo@gnu.org>
 ;;; Copyright © 2015 Mark H Weaver <mhw@netris.org>
 ;;; Copyright © 2016 Andreas Enge <andreas@enge.fr>
 ;;; Copyright © 2017 Marius Bakke <mbakke@fastmail.com>
@@ -252,7 +252,9 @@ the user's target storage device rather than on the RAM disk."
   (service-type (name 'configuration-template)
                 (extensions
                  (list (service-extension etc-service-type
-                                          /etc/configuration-files)))))
+                                          /etc/configuration-files)))
+                (description "Install the operating system configuration file
+templates under @file{/etc/configuration}.")))
 
 (define %configuration-template-service
   (service configuration-template-service-type #t))
diff --git a/gnu/tests.scm b/gnu/tests.scm
index 85f38ae8c9b..ca677d315b5 100644
--- a/gnu/tests.scm
+++ b/gnu/tests.scm
@@ -1,5 +1,5 @@
 ;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2016, 2017, 2018, 2019, 2020 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2016-2020, 2022 Ludovic Courtès <ludo@gnu.org>
 ;;; Copyright © 2017 Mathieu Othacehe <m.othacehe@gmail.com>
 ;;; Copyright © 2017 Tobias Geerinckx-Rice <me@tobias.gr>
 ;;; Copyright © 2021 Maxime Devos <maximedevos@telenet.be>
@@ -161,7 +161,10 @@
   (service-type (name 'marionette-repl)
                 (extensions
                  (list (service-extension shepherd-root-service-type
-                                          marionette-shepherd-service)))))
+                                          marionette-shepherd-service)))
+                (description "The @dfn{marionette} service allows a guest
+system (virtual machine) to be manipulated by the host.  It is used for system
+tests.")))
 
 (define* (marionette-operating-system os
                                       #:key