How do you expose application metrics with Spring Boot Actuator?

Table of Contents

• Introduction
• How to Expose Metrics with Spring Boot Actuator
  • 1. Add the Spring Boot Actuator Dependency
    • For Maven:
    • For Gradle:
  • 2. Configure Metric Endpoints
    • Exposing the Metrics Endpoint
    • Secure Endpoints
  • 3. Accessing the Metrics
  • 4. Viewing Specific Metrics
  • 5. Custom Metrics
    • Example of Custom Metrics
  • 6. Integrating with External Monitoring Systems
    • Integrating with Prometheus
• Conclusion

Introduction

Spring Boot Actuator is a powerful module that helps developers add production-ready features to their Spring Boot applications. One of the key features of the Actuator module is the ability to expose application metrics. These metrics are essential for monitoring and analyzing the performance and health of a Spring Boot application. The metrics provided by Spring Boot Actuator can include data such as HTTP request counts, response times, JVM memory usage, and system CPU usage, among others.

In this guide, we will explain how to expose application metrics with Spring Boot Actuator, how to configure metric endpoints, and how to integrate them with external monitoring tools.

How to Expose Metrics with Spring Boot Actuator

1. Add the Spring Boot Actuator Dependency

To expose metrics in a Spring Boot application, you first need to add the Spring Boot Actuator dependency to your project.

For Maven:

For Gradle:

This dependency brings in the necessary libraries for exposing metrics, health checks, and other management features provided by Spring Boot Actuator.

2. Configure Metric Endpoints

Once you’ve added the actuator dependency, you need to enable and configure the metric endpoints in your application.properties or application.yml file.

By default, Spring Boot Actuator exposes a set of built-in metric endpoints. However, you may want to configure which endpoints are exposed, their paths, and which specific metrics are enabled.

Exposing the Metrics Endpoint

The default endpoint for metrics is /actuator/metrics. To ensure it is exposed, configure it in your application.properties:

management.endpoints.web.exposure.include=metrics

To expose all Actuator endpoints, you can use:

This will make all Actuator endpoints, including health, info, metrics, and others, available.

Secure Endpoints

If you're working with sensitive data, securing your endpoints is essential. You can restrict access to Actuator endpoints using Spring Security.

For example, to secure the /actuator/metrics endpoint, you can add:

This configuration sets up basic authentication for Actuator endpoints.

3. Accessing the Metrics

Once you've exposed the metrics endpoint, you can access the metrics data via HTTP. For example, to view the application metrics:

This will return a list of all available metric names in the application, like:

4. Viewing Specific Metrics

You can query specific metrics by appending the metric name to the /metrics endpoint. For instance, to view JVM memory usage:

This will return a detailed view of the JVM memory usage:

You can replace jvm.memory.used with other metric names like http.server.requests, system.cpu.usage, etc., to track various aspects of your application’s performance.

5. Custom Metrics

Spring Boot Actuator allows you to create custom metrics tailored to your application. This can be useful for tracking specific business logic or application performance.

Example of Custom Metrics

You can create custom metrics by using Micrometer, which is the underlying metrics library used by Spring Boot Actuator.

In this example, a custom counter metric is created to track successful requests. The custom metric will be exposed in the /actuator/metrics endpoint as custom.requests.

6. Integrating with External Monitoring Systems

Once your application is exposing metrics, you can integrate Spring Boot Actuator with various external monitoring tools such as Prometheus, Grafana, New Relic, or Datadog.

Integrating with Prometheus

To integrate with Prometheus, you need to add the Prometheus Micrometer registry as a dependency:

Then, configure Prometheus to scrape metrics from your /actuator/prometheus endpoint:

Prometheus will then periodically scrape your application's metrics, which can be used to generate dashboards in Grafana.

Conclusion

Exposing application metrics using Spring Boot Actuator provides invaluable insights into the health, performance, and usage of your Spring Boot applications. By exposing metric endpoints, you can track various aspects of the application's behavior, from JVM memory usage to HTTP request handling and system CPU usage. The ability to integrate these metrics with external monitoring tools like Prometheus and Grafana further enhances the ability to observe and manage your application's performance in real-time. Custom metrics also allow you to track application-specific KPIs, making Spring Boot Actuator a powerful tool for any production environment.