Why NUT

The UPS is attached to the main host; everything else needs to know when the power drops so VMs and nodes shut down in order.

Setup

  1. Install nut on the host with the USB driver.
  2. Run nut-webapi so remote clients can poll battery status.
  3. Point node shutdown scripts at the NUT server status.

Gotchas

  • The USB driver claims the device exclusively — only one server can talk to it.
  • Test with upsc ups@localhost before wiring anything into shutdown hooks.