How do you implement custom actuator endpoints?

Table of Contents

Introduction

Spring Boot Actuator provides a range of built-in endpoints for monitoring and managing your application, such as health checks, metrics, and logging configurations. However, there are times when you need to implement custom endpoints to expose specific functionality that is unique to your application. Whether you need to create custom health checks, expose metrics, or add new management endpoints, Spring Boot Actuator allows you to extend its capabilities by implementing custom endpoints.

This guide will walk you through the process of creating custom actuator endpoints in a Spring Boot application, covering both custom health indicators and custom management endpoints.

Steps to Implement Custom Actuator Endpoints

1. Add Spring Boot Actuator Dependency

To implement custom actuator endpoints, you first need to ensure that the Spring Boot Actuator dependency is included in your project.

For Maven:

For Gradle:

2. Creating Custom Health Indicator

Spring Boot Actuator provides the HealthIndicator interface to create custom health checks for your application. This can be useful when you want to monitor specific application dependencies, external services, or any other aspect of your system.

Example: Custom Health Indicator

To create a custom health indicator, implement the HealthIndicator interface and override the health() method to define the health check logic.

CustomHealthIndicator.java:

In this example, the custom health check verifies whether an external service is available. If the service is reachable, the health status will be "UP"; otherwise, it will be "DOWN".

After creating the custom health indicator, it will automatically be exposed through the /actuator/health endpoint.

You can verify the custom health indicator by accessing:

The response will include your custom health check:

3. Creating Custom Metrics

If you want to expose custom metrics for monitoring purposes, you can use Spring Boot Actuator's MeterRegistry to register custom metrics. Custom metrics can include things like request counts, response times, or any other application-specific data.

Example: Custom Metric

To create custom metrics, inject the MeterRegistry and define a counter or gauge.

CustomMetrics.java:

In this example, we create a custom counter metric called custom_counter. Every time the incrementCustomCounter() method is called, the counter is incremented.

You can expose the custom metrics via the /actuator/metrics endpoint:

The response will show the current value of your custom metric:

4. Creating a Custom Actuator Endpoint

If you need to create a custom management endpoint other than health checks and metrics, you can create a custom actuator endpoint by extending AbstractEndpoint or Endpoint interface. This allows you to define the logic for the custom endpoint.

Example: Custom Management Endpoint

To create a custom endpoint, extend AbstractEndpoint and provide the desired logic.

CustomEndpoint.java:

In this example, we create a custom endpoint called /actuator/custom. When you access this endpoint, it will return the message "This is a custom endpoint response!".

To test it, you can navigate to:

The response will be:

5. Configuring Custom Endpoints Exposure

By default, custom endpoints may not be exposed. You can configure which endpoints to expose by updating the application.properties or application.yml file.

For example, to expose the custom endpoint /actuator/custom, add the following to application.properties:

This will ensure that the custom endpoint is accessible.

6. Securing Custom Actuator Endpoints

To secure custom actuator endpoints, you can use Spring Security to restrict access based on roles or permissions. For example, to secure the /actuator/custom endpoint:

SecurityConfig.java:

With this configuration, only users with the ADMIN role can access the /actuator/custom endpoint.

Conclusion

Spring Boot Actuator allows you to create custom endpoints to expose specific functionality needed for monitoring and managing your application. By implementing custom health indicators, metrics, and management endpoints, you can tailor the monitoring system to suit your application's needs. You can also secure these endpoints using Spring Security and configure which endpoints should be exposed or hidden.

With this level of customization, you can extend Spring Boot Actuator’s built-in capabilities to create a robust monitoring and management system for your application.

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