Spring Boot Actuator

What You’ll Learn 📚

• Introduction to Spring Boot Actuator
• Core concepts and key terminology
• Simple and progressively complex examples
• Common questions and troubleshooting tips

Introduction to Spring Boot Actuator

Spring Boot Actuator is a powerful tool that helps you monitor and manage your Spring Boot applications. It provides a set of built-in endpoints that give you insights into your application’s health, metrics, and more. Think of it as a health check-up for your app! 🩺

Key Terminology

• Endpoint: A URL that provides specific information or functionality.
• Metrics: Data points that provide insights into your application’s performance.
• Health Check: A way to determine if your application is running smoothly.

Getting Started: The Simplest Example

Let’s start with the simplest example to get a feel for how Spring Boot Actuator works.

Setup Instructions

1. Ensure you have Java and Maven installed on your machine.
2. Create a new Spring Boot project using Spring Initializr or your favorite IDE.
3. Add the Spring Boot Actuator dependency to your pom.xml file:

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

Basic Example

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class ActuatorExampleApplication {
    public static void main(String[] args) {
        SpringApplication.run(ActuatorExampleApplication.class, args);
    }
}

Running the Application

mvn spring-boot:run

Once the application is running, you can access the Actuator endpoints by navigating to http://localhost:8080/actuator/health in your browser.

Progressively Complex Examples

Example 1: Custom Health Indicator

Let’s create a custom health indicator to monitor a specific aspect of your application.

import org.springframework.boot.actuate.health.Health;
import org.springframework.boot.actuate.health.HealthIndicator;
import org.springframework.stereotype.Component;

@Component
public class CustomHealthIndicator implements HealthIndicator {
    @Override
    public Health health() {
        // Custom logic to determine health
        boolean healthy = checkCustomComponent();
        if (healthy) {
            return Health.up().withDetail("Custom Component", "Available").build();
        }
        return Health.down().withDetail("Custom Component", "Not Available").build();
    }

    private boolean checkCustomComponent() {
        // Simulate a health check
        return true;
    }
}

Example 2: Exposing Custom Metrics

Spring Boot Actuator allows you to expose custom metrics. Here’s how you can do it:

import io.micrometer.core.instrument.MeterRegistry;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

import javax.annotation.PostConstruct;

@Component
public class CustomMetrics {
    @Autowired
    private MeterRegistry meterRegistry;

    @PostConstruct
    public void init() {
        meterRegistry.gauge("custom.metric", 42);
    }
}

Example 3: Securing Actuator Endpoints

It’s important to secure your Actuator endpoints, especially in production environments.

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.config.annotation.web.configuration.WebSecurityConfigurerAdapter;

@Configuration
@EnableWebSecurity
public class SecurityConfig extends WebSecurityConfigurerAdapter {
    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http
            .authorizeRequests()
            .antMatchers("/actuator/**").authenticated()
            .and()
            .httpBasic();
    }
}

Common Questions and Answers

1. What is Spring Boot Actuator?

   It’s a tool that provides production-ready features to help you monitor and manage your application.

2. How do I enable Actuator endpoints?

   Add the Actuator dependency to your project, and the endpoints are enabled by default.

3. Can I customize Actuator endpoints?

   Yes, you can create custom endpoints and metrics.

4. How do I secure Actuator endpoints?

   Use Spring Security to secure your endpoints.

5. What are some common Actuator endpoints?

   /actuator/health, /actuator/info, /actuator/metrics.

Troubleshooting Common Issues

If you can’t access the Actuator endpoints, ensure that the Actuator dependency is correctly added and your application is running.

Lightbulb moment: Remember, Actuator is like a stethoscope for your app, helping you listen to its heartbeat! 💡

Common Mistakes

• Forgetting to add the Actuator dependency.
• Not securing endpoints in production.
• Ignoring custom health checks.

Practice Exercises

• Create a custom endpoint that returns a list of active users.
• Implement a health check for a database connection.
• Expose a custom metric that tracks the number of requests to a specific endpoint.

For more information, check out the Spring Boot Actuator Documentation.