Mains Power Monitor for Unraid

This plugin is a workaround for UPS units that cannot directly report a mains power failure to the Unraid server. Instead of a power-failure signal from the UPS, Unraid monitors the IPv4 address of a separate network device that is powered from normal mains and is not protected by an uninterruptible power supply (UPS), while Unraid itself remains UPS-backed.

Copyright © 2026 Ray Munro. Licensed under the GNU GPLv3.

Behaviour

• Pings the configured monitored-device IPv4 address.
• The monitored device must use normal mains power and must not be UPS-backed; Unraid itself should remain powered by the UPS.
• Records an outage after the configured consecutive failure threshold and immediately initiates Unraid's native clean shutdown (powerdown).
• Persists the pending outage under /boot/config/plugins/mains-power-monitor/ so it survives an Unraid shutdown/reboot.
• Stamps the pending record when Unraid services stop/shutdown during an outage. The pending record is written before shutdown is requested.
• On the same boot or a later boot, waits for consecutive successful pings and then sends one WARNING-level Unraid notification through configured notification agents.
• The recovery report includes loss time, shutdown time when recorded, approximate restart time, connectivity-confirmed time, and the loss-to-recovery interval.

Choose a device with a fixed/reserved IPv4 address that is normally reliable and powered from the same non-UPS mains supply you want to monitor — a router, switch, access point, small computer, printer, or another always-on network appliance, as long as it isn't UPS-backed.

Important limitation

This plugin does not measure mains voltage and does not receive a hardware power-failure signal from the UPS. It infers a probable mains outage from the disappearance of a network device deliberately left off UPS power. A reboot, failure, cabling problem, or other loss of that device or its network path can therefore look like a mains outage and can trigger the configured clean shutdown. If Unraid is powered off when mains returns, the exact restoration time cannot be observed; the recovery report gives the time connectivity was confirmed after Unraid restarted.

Safety note

Reaching the configured failure threshold intentionally shuts Unraid down. The default is four failed checks.

Installation

Via Community Applications: search for "Mains Power Monitor" in the Apps tab and click Install.

Manually: in the Unraid webGUI go to Plugins → Install Plugin and paste:

https://raw.githubusercontent.com/RayMunro/unraid-mains-power-monitor/main/mains-power-monitor.plg

or from the terminal:

plugin install https://raw.githubusercontent.com/RayMunro/unraid-mains-power-monitor/main/mains-power-monitor.plg

Then open Settings → User Utilities → Mains Power Monitor to configure the target IP and thresholds. It appears as a compact clickable tile; clicking it opens the full settings page. Everything the plugin needs is written by the .plg itself, so nothing else needs to be downloaded or copied by hand.

Uninstall

From Settings → Plugins, remove "mains-power-monitor" normally, or run:

plugin remove mains-power-monitor.plg