ups

Purpose

Polls a local NUT (Network UPS Tools) daemon for battery status and publishes power state transitions onto the MQTT bus. When the UPS runs below a configured critical-runtime threshold, triggers a graceful shutdown of the host.

Key files

vigilar/ups/monitor.py — UPSMonitor: NUT client, status parser, transition detection, MQTT publisher
vigilar/ups/shutdown.py — ShutdownSequence: publishes SYSTEM_SHUTDOWN and executes the OS shutdown
vigilar/ups/__init__.py

MQTT topics

Subscribes: none Publishes:

vigilar/ups/status (every poll; status, battery charge %, runtime seconds, input voltage, load %)
vigilar/ups/power_loss (transition OL -> OB/LB)
vigilar/ups/restored (transition back to OL)
vigilar/ups/low_battery (charge below low_battery_threshold_pct)
vigilar/ups/critical (runtime below critical_runtime_threshold_s, triggers shutdown)
vigilar/system/shutdown (published by ShutdownSequence)

Database tables

events — writes POWER_LOSS, POWER_RESTORED, LOW_BATTERY rows via insert_event
system_events — writes operator-facing notices ("Power loss detected — running on battery", critical shutdown messages)

Depends on

External NUT daemon reachable at [ups] nut_host:nut_port via the pynut2 client
storage — insert_event, insert_system_event

Consumed by

events — classifies vigilar/ups/* into POWER_LOSS / LOW_BATTERY / POWER_RESTORED
alerts — receives those classified events through rule actions
main supervisor — reacts to SYSTEM_SHUTDOWN so all subsystems can drain cleanly

Notes

The critical shutdown trigger fires when the UPS is not online AND battery.runtime < ups.critical_runtime_threshold_s AND no shutdown has already been triggered. The low-battery alert fires when battery.charge < ups.low_battery_threshold_pct while off mains. NUT reconnection uses exponential backoff capped at 120 seconds, so the monitor survives a temporary NUT restart without the supervisor having to restart it.

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ups