Metrics with Micrometer in Spring Boot - Mini Project: Build & Apply

Metrics with Micrometer in Spring Boot

📖 Scenario: You are building a simple Spring Boot application that tracks how many times a greeting endpoint is called. This helps you understand how often users access your service.

🎯 Goal: Create a Spring Boot application that uses Micrometer to count the number of times the /greet endpoint is accessed.

📋 What You'll Learn

Create a Spring Boot application with a REST controller

Add a Micrometer counter metric to track endpoint calls

Configure a counter variable to hold the metric

Increment the counter each time the endpoint is called

💡 Why This Matters

🌍 Real World

Tracking how often endpoints are called helps monitor application usage and detect issues early.

💼 Career

Understanding Micrometer metrics is essential for backend developers working on Spring Boot applications to build observable and maintainable services.

1

Create a REST controller with a greeting endpoint

Create a Spring Boot REST controller class named GreetingController with a method greet mapped to /greet that returns the string "Hello, World!".

Spring Boot

@RestController
public class GreetingController {
    // Your code here
}

Need a hint?

Use @RestController on the class and @GetMapping("/greet") on the method.

2

Add a Micrometer Counter variable

Add a private final Counter variable named greetCounter to the GreetingController class. Inject a MeterRegistry in the constructor and initialize greetCounter with Counter.builder("greet.calls").description("Number of greet calls").register(meterRegistry).

Spring Boot

@RestController
public class GreetingController {
    private final Counter greetCounter;

    public GreetingController(MeterRegistry meterRegistry) {
        // Your code here
    }

    @GetMapping("/greet")
    public String greet() {
        return "Hello, World!";
    }
}

Need a hint?

Use constructor injection to get MeterRegistry and build the counter.

3

Increment the counter in the greet method

Inside the greet method, add a line to increment the greetCounter by calling greetCounter.increment() before returning the greeting string.

Spring Boot

@RestController
public class GreetingController {
    private final Counter greetCounter;

    public GreetingController(MeterRegistry meterRegistry) {
        this.greetCounter = Counter.builder("greet.calls")
            .description("Number of greet calls")
            .register(meterRegistry);
    }

    @GetMapping("/greet")
    public String greet() {
        // Your code here
        return "Hello, World!";
    }
}

Need a hint?

Call greetCounter.increment() at the start of the greet method.

4

Add Micrometer dependency and enable metrics endpoint

Add the spring-boot-starter-actuator and micrometer-core dependencies to your pom.xml or build.gradle. Then, in application.properties, enable the metrics endpoint by adding management.endpoints.web.exposure.include=metrics.

Spring Boot

# Add dependencies and configuration in your project files
# Your code here

Need a hint?

Make sure to add both dependencies and enable metrics endpoint in properties.