Spring Boot Actuator for Monitoring

Table of Contents

1. What is Spring Boot Actuator?
2. Why Use Actuator?
3. Adding Actuator to Your Project
4. Exposing Actuator Endpoints
5. Commonly Used Endpoints
6. Customizing Endpoint Exposure
7. Securing Actuator Endpoints
8. Actuator and Health Monitoring
9. Metrics and Integration with Prometheus/Grafana
10. Creating Custom Actuator Endpoints
11. Summary

1. What is Spring Boot Actuator?

Spring Boot Actuator is a powerful feature of the Spring Boot ecosystem that enables production-ready features for monitoring and managing applications. It exposes various REST endpoints to monitor the internal state and behavior of your application without changing the code logic.

2. Why Use Actuator?

• Health Checks – Monitor application readiness and liveness.
• Metrics – View memory usage, CPU load, and JVM statistics.
• Audit Events – Track important system events.
• Thread Dumps – Analyze running threads.
• Environment Info – View environment variables, active profiles, etc.
• Integration – Easily integrate with Prometheus, Micrometer, and other monitoring tools.

3. Adding Actuator to Your Project

Add the Spring Boot Actuator dependency in your pom.xml:

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

Or if you’re using Gradle:

groovyCopyEditimplementation 'org.springframework.boot:spring-boot-starter-actuator'

4. Exposing Actuator Endpoints

By default, only the /actuator/health and /actuator/info endpoints are exposed over HTTP. To expose all or specific endpoints, configure your application.properties or application.yml:

propertiesCopyEditmanagement.endpoints.web.exposure.include=*

Or selectively:

propertiesCopyEditmanagement.endpoints.web.exposure.include=health,info,metrics,env

5. Commonly Used Endpoints

To get a full list, visit /actuator after exposing endpoints.

6. Customizing Endpoint Exposure

You can include/exclude endpoints individually:

propertiesCopyEditmanagement.endpoints.web.exposure.include=health,metrics
management.endpoints.web.exposure.exclude=beans,env

To change the base path for all actuator endpoints:

propertiesCopyEditmanagement.endpoints.web.base-path=/management

7. Securing Actuator Endpoints

Actuator endpoints can expose sensitive application internals. Use Spring Security to restrict access:

javaCopyEdit@Configuration
public class SecurityConfig extends WebSecurityConfigurerAdapter {

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http
            .authorizeRequests()
            .antMatchers("/actuator/health", "/actuator/info").permitAll()
            .antMatchers("/actuator/**").hasRole("ADMIN")
            .anyRequest().authenticated()
            .and()
            .httpBasic();
    }
}

You can also use application.properties to enable HTTP Basic authentication.

8. Actuator and Health Monitoring

The /actuator/health endpoint provides insight into the application’s status. You can include detailed health info:

propertiesCopyEditmanagement.endpoint.health.show-details=always

Spring Boot integrates with various health indicators:

• Database health
• Disk space
• Redis/Mongo/RabbitMQ connections
• Custom health indicators (covered below)

Custom Health Indicator

javaCopyEdit@Component
public class CustomHealthIndicator implements HealthIndicator {
    @Override
    public Health health() {
        // You can add logic here to check custom conditions
        return Health.up().withDetail("customService", "Available").build();
    }
}

9. Metrics and Integration with Prometheus/Grafana

Spring Boot integrates with Micrometer, which supports metrics exporting.

To use Prometheus:

xmlCopyEdit<dependency>
    <groupId>io.micrometer</groupId>
    <artifactId>micrometer-registry-prometheus</artifactId>
</dependency>

Expose the Prometheus endpoint:

propertiesCopyEditmanagement.endpoints.web.exposure.include=prometheus

Then access metrics at /actuator/prometheus and configure Prometheus to scrape it.

10. Creating Custom Actuator Endpoints

You can define your own actuator endpoints:

javaCopyEdit@Component
@Endpoint(id = "custom")
public class CustomEndpoint {

    @ReadOperation
    public Map<String, String> customEndpoint() {
        return Map.of("status", "Custom actuator endpoint working");
    }
}

The above creates an endpoint at /actuator/custom.

11. Summary

Spring Boot Actuator offers comprehensive monitoring and management capabilities for Spring Boot applications. By exposing standardized and custom endpoints, you gain real-time insights into application behavior, making it invaluable for debugging, observability, and DevOps automation.