Spring Boot Actuator is a production-readiness module that exposes built-in HTTP or JMX endpoints revealing an application's health, metrics, environment, and internal state, making it a core tool for monitoring and managing running services.
Key Points: • The /actuator/health endpoint reports overall and component-level health, including database and disk space checks. • /actuator/metrics exposes JVM, HTTP, and custom application metrics that can feed dashboards. • /actuator/env and /actuator/configprops surface active configuration for troubleshooting. • Endpoints integrate with Micrometer to export metrics to Prometheus, Datadog, or CloudWatch. • Sensitive endpoints should be secured and selectively exposed via management.endpoints.web.exposure.include.
Example: A team wires /actuator/health/readiness and /actuator/health/liveness into a Kubernetes deployment so the orchestrator automatically restarts or removes pods that report unhealthy, without any custom monitoring code.
Interview Tip: A concise interview answer is:
"Actuator gives me production-ready endpoints out of the box for health checks, metrics, and configuration inspection. I typically expose health and metrics to Kubernetes probes and Prometheus, and lock down the rest, so I get real-time visibility into the application without building custom monitoring."