Spring Boot Actuator, Probes, and Shutdown

Own the management surface: which endpoints exist, who can reach them, what health means to an orchestrator, and what happens between the first SIGTERM and process exit. Actuator is the only part of the service an operator talks to directly, so its exposure is a security decision and its semantics are a correctness decision.

When to use

• Choosing which endpoints to expose and on which port.
• Health checks return DOWN for the wrong reason, or a pod crash-loops on a downstream outage.
• Writing a custom HealthIndicator that cannot hang.
• A probe passes but the service cannot serve traffic, or fails while traffic is fine.
• Deciding what /actuator/info and /actuator/env may reveal.
• Requests are cut off during a rollout instead of finishing.
• Diagnosing an auto-configuration or a bean that is not active.

When not to use