Master Spring Boot Actuator: Enable Monitoring, Secure Endpoints, and Build Custom Metrics

What is Spring Boot Actuator?

Spring Boot Actuator is an independent module that adds production‑ready monitoring and management features to a Spring Boot application, exposing built‑in endpoints for health, configuration, logs, metrics, and more.

How to Enable Actuator

1. Add Dependency

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

For Gradle:

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

2. Configure Endpoints

In application.properties or application.yml enable the desired endpoints:

management.endpoints.web.exposure.include=*
management.endpoint.health.show-details=always

management.endpoints.web.exposure.include=*

– expose all endpoints. management.endpoint.health.show-details=always – show detailed health information.

Common Endpoints

/actuator/health

: Checks application health status. Example URL http://localhost:8080/actuator/health. /actuator/info: Shows basic application information. Example URL http://localhost:8080/actuator/info. /actuator/metrics: Exposes performance metrics. Example URL http://localhost:8080/actuator/metrics. /actuator/loggers: Allows dynamic log level changes. Example URL http://localhost:8080/actuator/loggers. /actuator/env: Displays environment properties. Example URL http://localhost:8080/actuator/env.

Example: Health Check

{
  "status": "UP",
  "components": {
    "db": {
      "status": "UP",
      "details": {
        "database": "MySQL",
        "validationQuery": "isValid()"
      }
    },
    "diskSpace": {
      "status": "UP",
      "details": {
        "total": 5000000000,
        "free": 3000000000
      }
    }
  }
}

Example: Metrics

Requesting http://localhost:8080/actuator/metrics returns the list of metric names:

{
  "names": [
    "jvm.memory.used",
    "jvm.memory.max",
    "http.server.requests",
    "system.cpu.usage"
  ]
}

Specific metric values can be fetched, e.g., http://localhost:8080/actuator/metrics/jvm.memory.used:

{
  "name": "jvm.memory.used",
  "measurements": [
    { "statistic": "VALUE", "value": 12345678 }
  ],
  "availableTags": [
    { "tag": "area", "values": ["heap", "nonheap"] }
  ]
}

Security Configuration

1. Basic Authentication

Add Spring Security credentials in application.properties:

spring.security.user.name=admin
spring.security.user.password=secret

Accessing any actuator endpoint now requires the configured username and password.

2. Restrict Endpoint Exposure

Limit which endpoints are publicly accessible:

management.endpoints.web.exposure.include=health,info

Only /health and /info will be exposed.

Custom Endpoint

Developers can create their own actuator endpoints to expose application‑specific data.

Code Example

package com.example.demo.actuator;

import org.springframework.boot.actuate.endpoint.annotation.Endpoint;
import org.springframework.boot.actuate.endpoint.annotation.ReadOperation;
import org.springframework.stereotype.Component;

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

    @ReadOperation
    public String customEndpoint() {
        return "This is a custom endpoint";
    }
}

After adding the class, the endpoint is reachable at http://localhost:8080/actuator/custom and returns the string defined above.

Conclusion

Spring Boot Actuator equips developers with ready‑made monitoring endpoints, rich metric data, security controls, and extensibility for custom endpoints, making it a powerful tool for observing, diagnosing, and securing applications in production environments.