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monitoring: RpiSofiaUndervoltage alerts on new brown-out, not until reboot
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The rpi-sofia under-voltage alert keyed off the sticky firmware bit
(rpi_under_voltage_occurred == 1), which latches on the first brown-out and
stays 1 until the Pi reboots. With alert-on-change routing it re-paged on every
boot cycle and sat firing for ~211h of the last 14d — Viktor reported "getting a
few of these lately" — and it disagreed with the HA-sofia dashboard, which shows
the live state and reads OK once voltage recovers.

Can't just switch to the live bit: rpi_under_voltage_now never registered once in
14d (brown-outs are sub-second and fall between the 1-min textfile-collector
samples), so the sticky bit is the only reliable detector.

Fix: edge-trigger on a NEW latch via increase(rpi_under_voltage_occurred[1h]) > 0.
Fires once per brown-out and auto-resolves ~1h later (~2h active over the same
14d instead of ~211h); counter-reset handling makes a clean reboot a no-op. Both
real brown-out events in the window are still caught. Docs updated in the same
commit (monitoring.md).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
This commit is contained in:
Viktor Barzin 2026-06-19 08:45:39 +00:00
parent fbf6f11038
commit fd77c0dc4f
2 changed files with 8 additions and 3 deletions
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docs/architecture/monitoring.md
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@ -146,7 +146,7 @@ Query examples (Grafana → Loki): `{job="rpi-sofia-journal"}`, `{job="rpi-sofia
**Dashboard** — `dashboards/rpi-sofia.json` ("RPi Sofia", Hardware folder): status, undervoltage/throttle, SoC temp, load, memory, root-fs free + read-only, network.
**Alerts** (group `RPi Sofia` in `prometheus_chart_values.tpl`): `RpiSofiaDown` (`up==0`), `RpiSofiaFilesystemReadonly` (`node_filesystem_readonly{mountpoint="/"}==1` — the SD-failure signature), `RpiSofiaUndervoltage` (`rpi_under_voltage_occurred==1`), `RpiSofiaHighTemp`.
**Alerts** (group `RPi Sofia` in `prometheus_chart_values.tpl`): `RpiSofiaDown` (`up==0`), `RpiSofiaFilesystemReadonly` (`node_filesystem_readonly{mountpoint="/"}==1` — the SD-failure signature), `RpiSofiaUndervoltage` (`increase(rpi_under_voltage_occurred[1h])>0` — edge-triggered on the sticky bit; the live `rpi_under_voltage_now` bit is too transient to catch at 1-min sampling, so it fires on a *new* brown-out and auto-resolves ~1h later instead of latching until reboot), `RpiSofiaHighTemp`.
**Recovery** — a systemd hardware watchdog (`RuntimeWatchdogSec=14s`, bcm2835 max ~15s) auto-reboots the Pi on a hard hang instead of leaving it dead for hours.