docker-unless-stopped-insufficient-for-critical-services

Prometheus exited with code 255 during dockerd recovery after a VPS reboot, and restart: unless-stopped with restart_count=0 silently gave up without retrying. unless-stopped does not guarantee resurrection after host-level restarts with non-zero exit codes. Critical services require an external watchdog cron (e.g., every 5 min: check container state, docker start if not running).