apcupsd-service: put UPS in hibernate mode when shutting down

This adds a special systemd service that calls "apcupsd --killpower"
(put UPS in hibernate mode) just before shutting down the system.
Without this command, the UPS will stay on until the battery is
completely empty.

modules/services/monitoring/apcupsd.nix

@@ -156,6 +156,28 @@ in
  };
  };
 
+ # A special service to tell the UPS to power down/hibernate just before the
+ # computer shuts down. (The UPS has a built in delay before it actually
+ # shuts off power.) Copied from here:
+ # http://forums.opensuse.org/english/get-technical-help-here/applications/479499-apcupsd-systemd-killpower-issues.html
+ systemd.services.apcupsd-killpower = {
+ after = [ "shutdown.target" ]; # append umount.target?
+ before = [ "final.target" ];
+ wantedBy = [ "shutdown.target" ];
+ unitConfig = {
+ Description = "APC UPS killpower";
+ ConditionPathExists = "/run/apcupsd/powerfail";
+ DefaultDependencies = "no";
+ };
+ serviceConfig = {
+ Type = "oneshot";
+ ExecStart = "${pkgs.apcupsd}/bin/apcupsd --killpower -f ${configFile}";
+ TimeoutSec = 0;
+ StandardOutput = "tty";
+ RemainAfterExit = "yes";
+ };
+ };
+
  };
 
 }