mc-webui/docs/watchdog.md

Container Watchdog

The Container Watchdog is a systemd service that monitors the mc-webui Docker container and automatically restarts it if it becomes unhealthy or if the LoRa device becomes unresponsive. This is useful for ensuring reliability, especially on resource-constrained systems or when the LoRa hardware hangs.

Features

• Health monitoring - Checks container status every 30 seconds
• Log monitoring - Monitors mc-webui logs for specific "unresponsive LoRa device" errors
• Automatic restart - Restarts the container when issues are detected
• Auto-start stopped container - Starts the container if it has stopped (configurable)
• Hardware USB reset - Performs a low-level USB bus reset (unbind/bind or DTR/RTS) if the LoRa device freezes. Note: USB reset is automatically skipped if a TCP connection is used.
• Diagnostic logging - Captures container logs before restart for troubleshooting
• HTTP status endpoint - Query watchdog status via HTTP API
• Restart history - Tracks all automatic restarts with timestamps

Installation

cd ~/mc-webui
sudo ./scripts/watchdog/install.sh

The installer will:

• Create a systemd service mc-webui-watchdog
• Start monitoring the container immediately
• Enable automatic startup on boot
• Create a log file at /var/log/mc-webui-watchdog.log

Usage

Check service status

systemctl status mc-webui-watchdog

View watchdog logs

# Real-time logs
tail -f /var/log/mc-webui-watchdog.log

# Or via journalctl
journalctl -u mc-webui-watchdog -f

HTTP Status Endpoints

The watchdog provides HTTP endpoints on port 5051:

# Service health
curl http://localhost:5051/health

# Container status
curl http://localhost:5051/status

# Restart history
curl http://localhost:5051/history

Diagnostic Files

When the container is restarted, diagnostic information is saved to:

/tmp/mc-webui-watchdog-mc-webui-{timestamp}.log

These files contain:

• Container status at the time of failure
• Recent container logs (last 200 lines)
• Timestamp and restart result

Configuration (Optional)

No configuration required - the installer automatically detects paths and sets sensible defaults.

If you need to customize the behavior, the service supports these environment variables:

Variable	Default	Description
MCWEBUI_DIR	(auto-detected)	Path to mc-webui directory
CHECK_INTERVAL	30	Seconds between health checks
LOG_FILE	/var/log/mc-webui-watchdog.log	Path to log file
HTTP_PORT	5051	HTTP status port (0 to disable)
AUTO_START	true	Start stopped container (set to false to disable)
USB_DEVICE_PATH	(auto-detected)	Path to the LoRa device for hardware USB bus reset

To modify defaults, create an override file:

sudo systemctl edit mc-webui-watchdog

Then add your overrides, for example:

[Service]
Environment=CHECK_INTERVAL=60
Environment=AUTO_START=false

Uninstall

sudo ~/mc-webui/scripts/watchdog/install.sh --uninstall

Note: The log file is preserved after uninstall. Remove manually if needed:

sudo rm /var/log/mc-webui-watchdog.log