Actuator: health, metrics and info

Production systems need health probes, metrics and diagnostics; Actuator provides them out of the box.

Add spring-boot-starter-actuator and the app gains management endpoints under /actuator. Only health is exposed over HTTP by default; expose more deliberately with management.endpoints.web.exposure.include=health,info,metrics,prometheus.

Key endpoints:

/actuator/health aggregates health indicators: database, disk space, Redis, message brokers, each auto-configured when the dependency is present. Show details with management.endpoint.health.show-details=when-authorized. On Kubernetes, /actuator/health/liveness and /actuator/health/readiness probe groups are enabled automatically.
/actuator/metrics lists Micrometer metrics: JVM memory and GC, HTTP request timings (http.server.requests), connection pool usage. Adding micrometer-registry-prometheus exposes /actuator/prometheus for scraping.
/actuator/info shows build and git information when configured; loggers changes log levels at runtime; env, beans, mappings, configprops and threaddump help debugging.

Record your own metrics by injecting MeterRegistry and creating counters and timers, or use the @Observed annotation with the Observation API for metrics plus traces. Write a custom HealthIndicator bean to report the state of a dependency Boot doesn't know about.

Endpoints like env and heapdump expose sensitive data: put the management port behind the firewall (management.server.port) or secure it with Spring Security.

Example

# application.properties
management.endpoints.web.exposure.include=health,info,metrics,prometheus
management.endpoint.health.show-details=when-authorized
management.server.port=8081

// PaymentsHealth.java: a custom indicator, shown as "payments" in /actuator/health
@Component
class PaymentsHealth implements HealthIndicator {
    public Health health() {
        boolean up = pingPaymentProvider();
        return up ? Health.up().withDetail("provider", "stripe").build()
                  : Health.down().withDetail("reason", "timeout").build();
    }
    private boolean pingPaymentProvider() { return true; }
}

@Service
class OrderService {
    private final Counter placed;
    OrderService(MeterRegistry registry) {
        placed = Counter.builder("orders.placed").tag("channel", "web").register(registry);
    }
    void place() { placed.increment(); }   // visible at /actuator/metrics/orders.placed
}

Remember

Actuator adds /actuator endpoints; only health is exposed by default
Health indicators are auto-configured for each dependency
Micrometer metrics export to Prometheus and other systems
Secure or isolate management endpoints

Watch out for

Exposing all endpoints (include=*) on the public port, leaking environment variables and heap dumps.

Check yourself

Which endpoint is exposed over HTTP by default after adding Actuator?

Official docs: docs.spring.io/spring-boot/reference/actuator/endpoints.html

Example

Remember

Watch out for

Check yourself

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