Exploring Spring Boot Actuator

Introduction to Spring Boot Actuator

Spring Boot Actuator is a powerful set of production-ready features that allow you to monitor and manage your Spring Boot applications. It provides a variety of endpoints that expose useful information and functionality about your application, such as health checks, metrics, environment properties, and more. With Spring Boot Actuator, you can gain insights into the behavior and performance of your application in real-time.

In this guide, we will delve into the world of Spring Boot Actuator, covering its key features and demonstrating how to integrate and utilize it in your Spring Boot projects.

Prerequisites

Before proceeding, make sure you have a basic understanding of Spring Boot and how to set up a Spring Boot project.

Enabling Spring Boot Actuator

Enabling Spring Boot Actuator is a straightforward process. In your Spring Boot project, you just need to add the Actuator dependency to your pom.xml (for Maven) or build.gradle (for Gradle):

Maven:

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

Gradle:

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

Once you’ve added the Actuator dependency, Spring Boot Actuator will be automatically enabled, and you can start exploring its features.

Key Spring Boot Actuator Endpoints

Spring Boot Actuator provides various endpoints that expose different types of information and functionality. Let’s explore some of the most commonly used endpoints:

1. Health Endpoint

The /actuator/health endpoint provides information about the health of your application. It can indicate whether your application is up and running or if there are any issues.

To access the health endpoint, simply navigate to http://localhost:8080/actuator/health (assuming your application is running on port 8080).

2. Info Endpoint

The /actuator/info endpoint displays arbitrary application information. You can customize this information by providing a info section in your application.properties or application.yml file.

3. Metrics Endpoint

The /actuator/metrics endpoint exposes a wide range of metrics about your application’s performance, memory usage, thread pools, and more.

For example, to access the metrics for memory usage, visit http://localhost:8080/actuator/metrics/memory.used (again, assuming your application is running on port 8080).

4. Environment Endpoint

The /actuator/env endpoint provides information about your application’s environment properties, including system properties, configuration properties, and more.

5. Custom Endpoints

You can also create custom endpoints by implementing your own management endpoints. This is useful for exposing application-specific information or functionality.

Enabling and Customizing Endpoints

You can configure which endpoints are enabled or disabled in your application by specifying properties in your application.properties or application.yml file. For example, to disable the info endpoint, you can add:

management.endpoints.web.exposure.include=health,metrics,env

This configuration will only expose the health, metrics, and environment endpoints.

Creating Custom Actuator Endpoints

While Spring Boot Actuator provides a set of built-in endpoints, you can also create custom endpoints to expose application-specific information or functionality. This allows you to extend the monitoring and management capabilities of your Spring Boot application.

Let’s create a simple custom endpoint that displays a custom message:

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!";
    }
}

In this example, we’ve defined a custom endpoint CustomEndpoint using the @Endpoint annotation. The @ReadOperation annotation indicates that this endpoint will handle HTTP GET requests.

Now, if you start your Spring Boot application and navigate to http://localhost:8080/actuator/custom, you will see the custom message displayed in the response.

Securing Actuator Endpoints

By default, Spring Boot Actuator endpoints are not exposed over HTTP. However, if you want to expose them, it’s important to consider security. You can secure Actuator endpoints using Spring Security.

Here’s an example of securing Actuator endpoints with basic authentication:

import org.springframework.boot.actuate.autoconfigure.security.servlet.EndpointRequest;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.security.config.annotation.web.builders.HttpSecurity;
import org.springframework.security.config.annotation.web.configuration.EnableWebSecurity;
import org.springframework.security.core.userdetails.User;
import org.springframework.security.core.userdetails.UserDetails;
import org.springframework.security.provisioning.InMemoryUserDetailsManager;

@Configuration
@EnableWebSecurity
public class SecurityConfig {

    @Bean
    public InMemoryUserDetailsManager userDetailsManager() {
        UserDetails user = User.withDefaultPasswordEncoder()
            .username("admin")
            .password("password")
            .roles("ADMIN")
            .build();

        return new InMemoryUserDetailsManager(user);
    }

    protected void configure(HttpSecurity http) throws Exception {
        http.authorizeRequests()
            .requestMatchers(EndpointRequest.toAnyEndpoint())
            .hasRole("ADMIN")
            .and()
            .httpBasic();
    }
}

In this configuration, we’ve enabled Spring Security, created an in-memory user with the role ADMIN, and configured basic authentication for Actuator endpoints.

Customizing Actuator Paths

By default, Actuator endpoints are exposed under the /actuator path. You can customize this path by adding the following property to your application.properties or application.yml:

management.endpoints.web.base-path=/custom-actuator

This configuration will move the Actuator endpoints to the /custom-actuator path.

Conclusion

Spring Boot Actuator provides a powerful set of tools for monitoring and managing your Spring Boot applications. By creating custom endpoints and securing them with Spring Security, you can tailor the Actuator functionality to your specific needs. Whether you’re exposing application-specific information or ensuring the security of your endpoints, Spring Boot Actuator offers the flexibility and extensibility required to effectively manage and monitor your applications in production environments.