services: admin: Support rebooting after an unattended upgrade

* gnu/services/admin.scm (unattended-upgrade-configuration): Add reboot?
field. When truthy, unattended upgrade will stop the shepherd root service,
triggering a reboot.
* doc/guix.texi (Unattended Upgrades): Document it.

Change-Id: I0af659b3c318421b1a7baa94dde3dadacc1fa10d
Signed-off-by: Ludovic Courtès <ludo@gnu.org>

2 files changed, 16 insertions, 1 deletions

diff --git a/doc/guix.texi b/doc/guix.texi
index bdaefe3802d..bc4d306c2dc 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -23088,6 +23088,10 @@ system to use for the upgrade.  If no value is provided the
     #~(@@ (guix system install) installation-os)))
 @end lisp
 
+@item @code{reboot?} (default: @code{#f})
+This field specifies whether the system should reboot after completing
+an unattended upgrade.
+
 @item @code{services-to-restart} (default: @code{'(mcron)})
 This field specifies the Shepherd services to restart when the upgrade
 completes.
diff --git a/gnu/services/admin.scm b/gnu/services/admin.scm
index 0b325fddb1e..4882883878a 100644
--- a/gnu/services/admin.scm
+++ b/gnu/services/admin.scm
@@ -420,6 +420,8 @@ which lets you search for packages that provide a given file.")
                         (default "30 01 * * 0"))
   (channels             unattended-upgrade-configuration-channels
                         (default #~%default-channels))
+  (reboot?              unattended-upgrade-configuration-reboot?
+                        (default #f))
   (services-to-restart  unattended-upgrade-configuration-services-to-restart
                         (default '(mcron)))
   (system-expiration    unattended-upgrade-system-expiration
@@ -443,6 +445,9 @@ which lets you search for packages that provide a given file.")
   (define services
     (unattended-upgrade-configuration-services-to-restart config))
 
+  (define reboot?
+    (unattended-upgrade-configuration-reboot? config))
+
   (define expiration
     (unattended-upgrade-system-expiration config))
 
@@ -512,7 +517,13 @@ which lets you search for packages that provide a given file.")
 
             ;; XXX: If 'mcron' has been restarted, perhaps this isn't
             ;; reached.
-            (format #t "~a upgrade complete~%" (timestamp))))))
+            (format #t "~a upgrade complete~%" (timestamp))
+
+            ;; Stopping the root shepherd service triggers a reboot.
+            (when #$reboot?
+              (format #t "~a rebooting system~%" (timestamp))
+              (force-output) ;ensure the entire log is written.
+              (stop-service 'root))))))
 
   (define upgrade
     (program-file "unattended-upgrade" code))