Comparison
Graceful shutdownvsReadiness probe
Graceful shutdown
on SIGTERM you stop accepting new requests, finish the ones in flight, and only then exit.
Ending a process in a way that does not drop work: deregister from the load balancer, stop accepting, complete in-flight requests, close connections, exit. Without it, every deploy sheds a burst of errors proportional to your request rate. The grace period must exceed your longest normal request, or the platform kills you mid-request anyway.
Full entry →Readiness probe
the instance says "not yet" while the cache warms, so the load balancer keeps traffic off it until it is genuinely able to serve.
A health check whose failure means "stop sending traffic", without restarting the instance. This is the probe that may legitimately consider dependencies, since removing one instance from rotation is recoverable. Conflating it with liveness is one of the most common Kubernetes configuration mistakes.
Full entry →