nut on Debian bullseye: issues with UID and default config

[Marc SCHAEFER <schaefer@alphanet.ch>]

Hello,

I run a nut-server & nut-client on Debian bullseye connected to an UPS.
It works very well: there are syslog messages for when the current is
down and it's on battery, I can see the various statistics with upsc.

However, it does not seem it really shuts down when low on battery.

I noticed that upsmon & upssched run under user nut, not root, so
upsmon.conf's SHUTDOWNCMD "/sbin/shutdown -h +0" does not work.

As a work-around I installed sudo and added this to /etc/sudoers:

nut     ALL=(root) NOPASSWD: /root/scripts/all-machines-shutdown.sh

and configured "sudo /root/scripts/all-machines-shutdown.sh" as the
above SHUTDOWNCMD definition.

This script is a bit complex because it needs to stop various machines
in the correct order, but so far it looks ok.

However, I noticed that sometimes the time to do the complete shutdown
is quite long and when the batteries start to get a bit older,
it could mean there is not enough time till the battery is completely
depleted.

So I modified upsmon.conf so to use upssched to start the shutdown
after a three minutes of "on battery" has passed (in my region, either
the cut is 10 seconds or less, or it's a few hours anyway).

This gives, in upsmon.conf:

   NOTIFYCMD /sbin/upssched
   NOTIFYFLAG ONLINE SYSLOG+EXEC
   NOTIFYFLAG ONBATT SYSLOG+EXEC
   NOTIFYFLAG LOWBATT SYSLOG+EXEC

and in upssched.conf:

   CMDSCRIPT /usr/local/bin/upssched-cmd-special
   
   AT ONBATT * START-TIMER onbattwarn 180
   AT ONLINE * CANCEL-TIMER onbattwarn
   
   AT ONBATT * EXECUTE onbatt
   AT ONLINE * EXECUTE onpower
   
   AT REPLBATT * EXECUTE replace_batt

and in /usr/local/bin/upssched-cmd-special, something like:

   case $1 in
           onbattwarn) logger -t $0 "should shutdown $(id)"
                       sudo /root/scripts/all-machines-shutdown.sh
                       ;;
           onbatt|onpower|replace_batt) logger -t $0 "$1 $(id)" ;;
   
           *)
                   logger -t $0 "Unrecognized command: $1"
                   ;;
   esac

I also noticed that without the sudo it does not work either.

However, there is more:  if I do not change, in upssched.conf two
definitions to:

   PIPEFN /run/nut/upssched.pipe
   LOCKFN /run/nut/upssched.lock

it fails because it looks the startup scripts do not create the
/run/nut/upssched/ directory which seems referenced by the default
configuration.

I just checked, and the stock nut-server and nut-client packages from
bullseye still have those default configurations.  I do not have
a system managing an UPS running bookworm yet.

So, either this post will be a documentation helping others, or an
expert could tell me what I did wrong in the above :)