What is the purpose of the @EnableActuator annotation?

Table of Contents

• Introduction
  • What is Spring Boot Actuator?
  • How Does @EnableActuator Work?
  • When to Use @EnableActuator
  • Actuator Endpoints in Spring Boot
    • Example of /health Endpoint:
  • Configuring Actuator Endpoints
  • Practical Example
• Conclusion

Introduction

In Spring Boot, the Actuator is a set of built-in tools that help you monitor and manage your application in production. It provides essential endpoints such as health checks, metrics, and application information. The @EnableActuator annotation is used to enable Actuator functionality in a Spring Boot application. This guide explains the purpose of the @EnableActuator annotation, how it works, and why it’s important for your Spring Boot applications.

What is Spring Boot Actuator?

Spring Boot Actuator is a powerful tool that provides a variety of production-ready features to monitor and manage your application. These include:

• Health Checks: To check if your application is running properly.
• Metrics: To track application performance (e.g., memory usage, request count).
• Application Info: To expose metadata about your app, like version, environment, etc.
• Logging: To manage logging levels dynamically.
• Auditing: To monitor user actions and activity.

To activate Actuator functionality in your Spring Boot application, you typically use the @EnableActuator annotation, which explicitly marks the application for Actuator’s features. However, starting from Spring Boot 2.x, you no longer need to use @EnableActuator explicitly, as Actuator is already included by default when you add the spring-boot-starter-actuator dependency.

How Does @EnableActuator Work?

The @EnableActuator annotation was used in older versions of Spring Boot (prior to 2.x) to explicitly enable Actuator's monitoring and management features. With Spring Boot 2.x and beyond, the inclusion of the spring-boot-starter-actuator dependency automatically enables the Actuator functionality, making the use of the @EnableActuator annotation unnecessary.

For older versions, @EnableActuator enabled certain features like:

• Exposing Actuator Endpoints: The annotation would automatically expose key endpoints such as /health, /metrics, and /info.
• Enabling Auto-Configuration: It would trigger the auto-configuration required for the various Actuator modules.
• Facilitating Customization: Actuator endpoints could be further customized by modifying the application properties or through configuration classes.

When to Use @EnableActuator

In modern Spring Boot applications (version 2.x and above), you typically don’t need to use @EnableActuator. Instead, you just need to include the spring-boot-starter-actuator dependency, and Spring Boot will automatically configure Actuator for you.

However, if you are working with a version of Spring Boot prior to 2.x or if you’re dealing with specific configurations where you want to manually control the activation of Actuator functionality, you might still see @EnableActuator used. Here’s an example of how it was used:

Example:

Actuator Endpoints in Spring Boot

Actuator exposes several useful endpoints out of the box, such as:

• /health: Provides the health status of the application (e.g., whether it is running fine or facing issues).
• /metrics: Exposes metrics related to the application, such as JVM memory usage, HTTP request counts, etc.
• /info: Displays application metadata like build information, environment variables, and custom information.
• /env: Exposes the environment properties of the application.

You can also expose more endpoints like /prometheus, /beans, and /loggers to get more in-depth application details.

Example of /health Endpoint:

Once Actuator is enabled, you can access the /health endpoint to check the status of your application:

If the application is healthy, you will see:

Configuring Actuator Endpoints

You can configure which Actuator endpoints should be exposed or restricted through the application.properties or application.yml file.

For example, to expose only specific endpoints:

To disable an endpoint:

Practical Example

Step 1: Add Actuator Dependency

First, add the spring-boot-starter-actuator dependency to your project. This dependency will automatically enable Actuator functionality.

For Gradle:

Step 2: Expose Endpoints (Optional)

In application.properties, configure which endpoints to expose or restrict:

Step 3: Access Actuator Endpoints

You can now access various Actuator endpoints. For example, the /health endpoint can be accessed like this:

This will provide the health status of the application.

Conclusion

In modern Spring Boot versions (2.x and above), the @EnableActuator annotation is no longer required. Simply adding the spring-boot-starter-actuator dependency will automatically enable the Actuator functionality. The main purpose of the annotation in earlier versions was to enable Actuator's monitoring and management features and expose important endpoints such as health checks and metrics. By leveraging Spring Boot Actuator, you can easily monitor the health, metrics, and other vital statistics of your application in a production environment.