NUT (Network UPS Tools)

NUT is a tool that allows exposing a UPS (Uninturrepted Power Supply) in the network. It supports multiple vendors. You can check of supported devices here.

My current setup features a EATON Ellipse ECO 1200 UPS.

The installation has been tested on my Thinkpad laptop running Fedora 42, then installed on RHEL9 virtual machine.

The UPS can only be controlled via a USB connection. For the virtual machine case it has to be passed through from the VM host.

The initial setup on Fedora relied mainly on this forum, with a couple tweaks:

At the end, the guide proceeds to setup httpd to expose the monitor script. However the suggested setup (using nut-cgi-bin endpoint) didn't work. I instead proceeded the modify the pre-configured cgi-bin endpoint to point to the dir where the NUT .cgi scripts lived (/var/www/nut-cgi-bin/). This was done in the default httpd conf:
```
ScriptAlias /cgi-bin/ "/var/www/nut-cgi-bin/"

</IfModule>

#
# "/var/www/cgi-bin" should be changed to whatever your ScriptAliased
# CGI directory exists, if you have that configured.
#
<Directory "/var/www/nut-cgi-bin/">
    AllowOverride None
    Options None
    Require all granted
</Directory>
```

On RHEL9, the setup was a bit more tedious than anticipated: - upsd was complaining about missing libusb, turns out the libusb library was containing extra information about version of the lib. Resolution was to create a symlink pointing to the available lib file. - Some permission issues, resolved by adding user = root directive on top of the ups.conf file. - SELinux refraining the nut user from accessing certain files. This can be either resolved by disabling SELinux or adding a policy for the concerned files (check kernel messages for more info). - The nut-server service wasn't able to start up automatically even when enabled. Perhaps it is waiting for some other target to start before. Resolved it by having a @reboot directive on cron that starts it up upon reboot.