services: power: Add apcupsd.

* gnu/services/power.scm (apcupsd-service-type): Create service and
  configuration.

no auto-start

gnu/services/power.scm

@@ -0,0 +1,72 @@
+;;; GNU Guix --- Functional package management for GNU
+;;; Copyright © 2023 Karl Hallsby <karl@hallsby.com>
+;;;
+;;; This file is part of GNU Guix.
+;;;
+;;; GNU Guix is free software; you can redistribute it and/or modify it
+;;; under the terms of the GNU General Public License as published by
+;;; the Free Software Foundation; either version 3 of the License, or (at
+;;; your option) any later version.
+;;;
+;;; GNU Guix is distributed in the hope that it will be useful, but
+;;; WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;;; GNU General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU General Public License
+;;; along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.
+
+(define-module (gnu services power)
+  #:use-module (gnu packages power)
+  #:use-module (gnu services)
+  #:use-module (gnu services shepherd)
+  #:use-module (guix gexp)
+  #:use-module (guix records)
+  #:use-module (guix modules)
+  #:use-module (srfi srfi-1)
+  #:export (apcupsd-configuration
+            apcupsd-service-type))
+
+(define-record-type* <apcupsd-configuration>
+  apcupsd-configuration make-apcupsd-configuration
+  apcupsd-configuration?
+  ;; file-like object
+  (package apcupsd-configuration-package
+           (default apcupsd)))
+
+(define (apcupsd-shepherd-service config)
+  "Return a list of <shepherd-service>s for apcupsd with CONFIG."
+
+  (define package
+    (apcupsd-configuration-package config))
+
+  (define apcupsd-command
+    #~(list (string-append #$package "/sbin/apcupsd")
+            "-b" ;; Do not fork off to background
+            ;; "-f" "config-file"
+            "-d1"))
+
+  (list (shepherd-service
+         (documentation "apcupsd UPS monitoring daemon.")
+         (requirement '(networking syslogd))
+         (provision '(apcupsd))
+         ;; Use make-inetd-constructor??
+         (start #~(make-forkexec-constructor #$apcupsd-command))
+         (stop #~(make-kill-destructor))
+         (actions (list (shepherd-configuration-action config))))))
+
+(define (extend-apcupsd-configuration config extras)
+  "Extend CONFIG with the extra EXTRAS."
+  (apcupsd-configuration
+   (inherit config)))
+
+(define apcupsd-service-type
+  (service-type (name 'apcupsd)
+                (description
+                 "Monitor APC UPSes using the apcupsd daemon, @command{apcupsd}.")
+                (extensions
+                 (list (service-extension shepherd-root-service-type
+                                          apcupsd-shepherd-service)))
+                (compose concatenate)
+                (extend extend-apcupsd-configuration)
+                (default-value (apcupsd-configuration))))