Very brief overview

'upsd' is the server, 'upsmon' is the client.

• ups.conf - this defines the UPSes that are connected to the server. You might see a process running like "/lib/nut/newhidups -a YOUR_UPS_NAME"
• upsd.conf - the upsd daemon is the interface for other programs to connect and query the directly-connected UPSes. This config file controls some access restrictions.
• upsmon.conf - upsmon is the program that periodically connects to upsd to get the status, and can run commands (eg to shutdown your server if the battery gets low)

Other things like Nagios have their own clients that connect directly to upsd to query the status.

Sample Configuration

This is a simple way of setting up the NUT ups monitoring system to shut servers down well before you get to powerfail status. If you lose power for more than about 5 seconds, chances are pretty good you're going to have lost it for a while, so you may as well shut things down now

It will, on the first ONBATT signal from the UPS, start a 30 second timer. If the power does not return during this time it will schedule a 2 minute shutdown, after which the box is shutdown cleanly. If power returns at all during this time, the shutdown will be cancelled. -- DanielLawson

/etc/nut/ups.conf

[mge]
   ## USB cable
   #driver = newhidups
   #port = auto
   ## SNTMP
   #driver = snmp-ups
   #port = 1.2.3.4
   #mibs = mge
   desc = "MGE UPS"

/etc/nut/upsd.conf

ACL all 0.0.0.0/0
ACL localhost 127.0.0.1/32

ACCEPT localhost
REJECT all

/etc/nut/upsd.users

# Supervision user
[admin]
       password = password
       allowfrom = localhost
       actions = SET
       instcmds = ALL

# Protection user
[monuser]
       password  = monitor
       allowfrom = localhost
       upsmon master

/etc/nut/upsmon.conf

MONITOR mge@localhost 1 monuser monitor master
MINSUPPLIES 1
SHUTDOWNCMD "/sbin/shutdown -h +0"
POLLFREQ 5
POLLFREQALERT 5
HOSTSYNC 15
DEADTIME 15
#POWERDOWNFLAG /etc/killpower
RBWARNTIME 43200
NOCOMMWARNTIME 300
FINALDELAY 5
NOTIFYCMD /sbin/upssched
NOTIFYFLAG ONBATT WALL+SYSLOG+EXEC
NOTIFYFLAG ONLINE WALL+SYSLOG+EXEC
NOTIFYFLAG LOWBATT WALL+SYSLOG+EXEC
NOTIFYFLAG FSD WALL+SYSLOG+EXEC

/etc/nut/upssched.conf

CMDSCRIPT /usr/local/bin/upssched-cmd
PIPEFN /var/run/upssched/upssched.pipe
LOCKFN /var/run/upssched/upssched.lock

AT ONBATT * START-TIMER early-shutdown 30
AT LOWBATT * START-TIMER early-shutdown 30
AT ONLINE * CANCEL-TIMER resume
AT ONLINE * EXECUTE resume
AT FSD * EXECUTE forced-shutdown

GlennRamsey - On Ubuntu 8.04 the above script doesn't work. According to the man page the line:

AT ONLINE * CANCEL-TIMER resume

should be:

AT ONLINE * CANCEL-TIMER early-shutdown resume

but that seemed to cause a problem with cancelling the shutdown, after 30s had elapsed

AT ONLINE * CANCEL-TIMER early-shutdown

seems to work properly. I suspect the issue was related to the 'resume' command being given by both 'AT ONLINE' events.

/usr/local/bin/upssched-cmd

#!/bin/bash
# time in minutes
time=2
case "${1}" in
        early-shutdown)
                logger -t upssched-cmd "Early Shutdown"
                shutdown -h +$time powerevent
        ;;
        resume)
                logger -t upssched-cmd "Resume"
                [ -f /var/run/shutdown.pid ] && shutdown -c || exit 0
        ;;
        forced-shutdown)
                logger -t upssched-cmd "Forced Shutdown"
                shutdown -h +$time powerevent-forced

        ;;
        *)
                logger -t upssched-cmd "Unknown command: ${1}"
        ;;
esac

Notes

On Ubuntu 8.04 I had to add 'RUN_AS_USER root' to upsmon.conf in order for the early shutdown script to work. I guess one could achieve the same effect by giving the nut user permission to run shutdown command. -- GlennRamsey

The Socomec NETYS PE UPS available from Dick Smith works with nut using the megatec_usb driver. -- GlennRamsey

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Part of CategorySystemAdministration