To implement auto-restart and health checks, you need mechanisms to monitor application health and automatically recover from failures. Auto-restart ensures your service resumes operation after crashes, while health checks validate whether the application is functioning correctly. These features are critical for maintaining reliability in production systems, especially in containerized or distributed environments.
For auto-restart, use process managers or orchestration tools. For example, systemd (on Linux) allows defining service units with Restart=on-failure to automatically restart failed processes. In containerized setups like Docker, use the --restart unless-stopped flag to relaunch containers if they exit unexpectedly. Kubernetes takes this further with livenessProbe and restartPolicy in pod definitions—if a container fails a liveness check, Kubernetes terminates and recreates it. Tools like PM2 for Node.js also offer built-in process monitoring and auto-restart for application crashes. For custom scripts, implement a watchdog timer that triggers a restart if the application doesn’t respond within a timeout period.
Health checks involve creating endpoints or scripts that verify critical components. For web services, add a /health endpoint that checks database connections, external dependencies, or resource usage (e.g., memory, disk space). In Kubernetes, configure livenessProbe to ping this endpoint periodically. If the endpoint returns a non-200 status, the system triggers a restart. For non-HTTP services, use command-based checks (e.g., curl localhost:8080/health in Docker’s HEALTHCHECK instruction). Include both “liveness” (is the app running?) and “readiness” (is it ready to serve traffic?) checks to avoid routing requests to unhealthy instances. Tools like Consul or AWS Elastic Load Balancer can also perform health checks and route traffic accordingly. Test failure scenarios—simulate crashes or resource exhaustion to ensure your configuration behaves as expected.