A service registry is only as useful as its honesty. Consul keeps a catalog of registered instances and attaches health checks to them, so a caller asking where a healthy instance of a service lives gets an answer that changes as reality changes. Registration is trivial; the check is the whole product, because a registry that lists dead instances is worse than a static list — it actively routes traffic into a hole. ...
A slow start is not a dead process: readiness shields traffic while liveness only cares about keeping the process alive. Teams wire a single HTTP endpoint into both probes, and then every slow dependency becomes a restart loop — the app needs time, liveness refuses to grant it. Two probes exist because “not ready” and “dead” demand opposite responses: one asks for time, the other for a restart. ...
A probe result is evidence consumed by a control loop. Kubernetes does not infer your application’s recovery strategy from a route named healthz. The probe type, result, configured thresholds, and container lifecycle determine what happens next. Treating every failure as “restart the Pod” erases distinctions that directly affect availability. ...