2.2.1 Health Checks
GET /health (or a probe) returns 200 when the process can serve work. Liveness means “restart me if this fails.” Readiness means “do not send traffic yet.”
Why it matters
Without probes, the balancer keeps sending requests to a crashed or warming instance.
How it is used
Keep the check fast. Do not hit the production database on every probe if that database is the thing that is down — you will flap the whole fleet. Check local process health; use a separate deeper check for dependencies.