Monitoring Custom Metrics with Spring Boot Actuator

Monitoring Custom Metrics with Spring Boot Actuator

Overview

Spring Boot Actuator provides powerful features for monitoring and managing your Spring Boot application in production environments. One of its key functionalities is exposing various metrics, such as CPU usage, memory usage, and HTTP request statistics, via built-in endpoints. In addition to these default metrics, Actuator allows developers to expose custom metrics tailored to specific application requirements. This capability is essential for gaining deeper insights into application behavior, performance, and health.

How to Expose Custom Metrics

1. Dependency Setup:
   First, ensure that Spring Boot Actuator is included as a dependency in your pom.xml or build.gradle file. Actuator is typically included by default in most Spring Boot starters but can be added explicitly if needed.

Example pom.xml snippet:

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

2. Define Custom Metrics:
   To expose custom metrics, you'll create a component that uses Actuator's MeterRegistry to register and publish metrics. MeterRegistry is an interface provided by Micrometer, which is the underlying library for metrics in Spring Boot Actuator.

Example of defining a custom metric bean:

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

@Component
public class CustomMetrics {

private final MeterRegistry meterRegistry;

@Autowired
public CustomMetrics(MeterRegistry meterRegistry) {
this.meterRegistry = meterRegistry;
}

public void recordCustomMetric(int value) {
meterRegistry.counter("custom.metric").increment(value);
}
}

In this example, CustomMetrics defines a method recordCustomMetric that increments a counter metric named custom.metric.

3. Exposing Metrics Endpoint:
   By default, Actuator automatically exposes metrics through the /actuator/metrics endpoint. Custom metrics will be accessible via this endpoint once they are registered using MeterRegistry.

4. Accessing Custom Metrics:
   You can access custom metrics via HTTP GET requests to the Actuator's metrics endpoint. For example, to retrieve the value of custom.metric, you can make a request to /actuator/metrics/custom.metric.

Handling Errors and Troubleshooting

If you encounter errors while working with custom metrics in Spring Boot Actuator, they are often related to misconfiguration or incorrect usage:

• Error: Metric not found or returning zero.

• Solution: Ensure that the metric is correctly registered with MeterRegistry and that the application is generating data for the metric.

• Error: Actuator endpoints not accessible or returning 404.

• Solution: Verify Actuator dependencies are correctly included, and endpoints are enabled in application.properties or application.yml.

References

For further details on configuring and utilizing Spring Boot Actuator for custom metrics, refer to the official documentation:

• Spring Boot Actuator Documentation
• Micrometer Documentation

These resources provide comprehensive guides, examples, and troubleshooting tips to effectively integrate and utilize Actuator's monitoring capabilities in your Spring Boot applications.