Spring Boot Actuator

Introduction

Once an application is deployed, someone needs a way to answer basic operational questions without reading source code: is it up, is it healthy, how much memory is it using? Spring Boot Actuator answers exactly those questions by exposing production-ready endpoints for monitoring and management. In this lesson you will add the Actuator starter, inspect /actuator/health, and expose additional endpoints including metrics.

What Is Actuator?

Actuator is a Spring Boot starter that adds a set of HTTP endpoints (and optionally JMX beans) exposing information about the running application - health status, environment properties, configured beans, HTTP request metrics, thread dumps, and more. It is the standard way production Spring Boot applications integrate with monitoring tools, load balancer health checks, and container orchestration platforms like Kubernetes.

Adding the Actuator Starter

Add spring-boot-starter-actuator as a dependency. No further configuration is required to get basic endpoints working.

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-actuator</artifactId>
</dependency>

The Health Endpoint

The health endpoint returns a simple status that load balancers and orchestrators use to decide whether an instance is receiving traffic. By default it returns only a top-level status, but you can show more detail.

curl http://localhost:8080/actuator/health

# application.properties
management.endpoint.health.show-details=always

Actuator automatically detects components on the classpath - such as a DataSource - and contributes a health indicator for each one, so the database check above appears with no extra code once a datasource is configured.

Exposing More Endpoints

Use management.endpoints.web.exposure.include to control which endpoints are reachable over HTTP. A comma-separated list names specific endpoints, or * exposes everything (only recommended behind a secured, internal network).

# application.properties
management.endpoints.web.exposure.include=health,info,metrics,env

curl http://localhost:8080/actuator

Metrics Endpoint

The metrics endpoint exposes individual measurements. Hitting /actuator/metrics on its own lists every available metric name; appending a specific name returns that metric's value.

curl http://localhost:8080/actuator/metrics/jvm.memory.used

Securing Actuator Endpoints

Endpoints like /actuator/env and /actuator/beans can reveal configuration details, including things that overlap with secrets if you are not careful. If Spring Security is on the classpath, restrict access so only authorized callers can reach sensitive endpoints.

@Bean
public SecurityFilterChain actuatorSecurity(HttpSecurity http) throws Exception {
    http.securityMatcher("/actuator/**")
        .authorizeHttpRequests(auth -> auth
            .requestMatchers("/actuator/health", "/actuator/info").permitAll()
            .anyRequest().hasRole("ADMIN")
        )
        .httpBasic(Customizer.withDefaults());
    return http.build();
}

Common Mistakes

Best Practices

Frequently Asked Questions

Key Takeaways

Summary

Actuator turns operational questions - is it up, is it healthy, how is it performing - into simple HTTP endpoints your monitoring tools can consume automatically. Add the starter, expose only what you need, and secure anything sensitive before shipping to production.