9d52e46d1e
On 2026-07-09 a kernel keyring-GC oops left the player stuck in uninterruptible D-state while systemd, SSH, and the Flask app stayed alive -- so the box sat dead all night instead of recovering. A plain systemd/hardware watchdog only fires on a TOTAL hang and would not have caught that partial wedge. mediapi-watchdog.service (Type=simple, Restart=always, runs as root) pings mpv over its JSON IPC socket every 30s; after ~3 min of continuous failure it forces a reboot (systemctl reboot -ff, then SysRq as a kernel-level fallback that works even when userspace is wedged). A D-state mpv accepts the socket connect but never replies, so the ping times out and is caught. install.sh installs + enables it. Verified: no false positives while mpv is healthy; correctly detects a stopped mpv and reaches the reboot decision (tested in dry-run). Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
15 lines
424 B
Text
15 lines
424 B
Text
[Unit]
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Description=MediaPi watchdog -- reboots the Pi if the mpv player wedges
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After=mediapi-mpv.service
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Wants=mediapi-mpv.service
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[Service]
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Type=simple
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# Runs as root (no User=): must be able to force a reboot, including via SysRq,
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# to recover a box whose player is wedged in uninterruptible D-state.
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ExecStart=${PROJECT_DIR}/scripts/mediapi-watchdog.sh
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Restart=always
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RestartSec=10
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[Install]
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WantedBy=multi-user.target
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