When apcupsd has initiated a shutdown, systemd always ends up waiting
for it to stop ("A stop job is running for UPS daemon"). This is weird,
because in the journal one can clearly see that apcupsd has received the
SIGTERM signal and has already quit (or so it seems). This reduces the
wait time from 90 seconds (default) to just 5. Then systemd kills it
with SIGKILL.
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.
Each attribute in this option should name an apcupsd event and the
string value it contains will be executed in a shell in response to that
event. See "man apccontrol" for the list of events and what they
represent.
Now it is easy to hook into the apcupsd event system:
services.apcupsd.hooks = {
onbattery = ''# shell commands to run when the onbattery event is emitted'';
doshutdown = ''# shell commands to notify that the computer is shutting down'';
};
apcupsd is a daemon for controlling APC UPSes. It is very simple to
configure. If you have an USB based UPS, the default settings should be
useable without further adjustments:
services.apcupsd.enable = true;
This will give you autodetection of USB UPSes, network access limited to
localhost (for security) and the shutdown sequence will be started when
the system when the battery level is below 50 percent, or when the UPS
has calculated that it has 5 minutes or less of remaining power-on time.
You can provide your own configuration file contents with this option:
services.apcupsd.configText = "contents of apcupsd.conf";
Bug/annoyance 1: When apcupsd calls "wall" (on powerfail etc. events),
it prints an error message because stdout is not connected to a tty (it
is connected to the journal):
wall: cannot get tty name: Inappropriate ioctl for device
The message still gets through though, to ctrl-alt-f[1-6] terminals.
Bug/annoyance 2: apcupsd tries to call "mail" (on powerfail etc.
events), and that fails because I'm not passing in any mail program at
the moment (because that would require more configuration options). A
solution to this would be to simply let the user fully configure the
apcupsd event handling logic in nix.
