Adding Custom metrics in Spring Boot

spring-boot-actuator makes it easy to add custom metrics to the Spring Boot application. For example, we would like to know, how many times a particular method was executed in a service.
What we would need to do is just autowire CounterService and add the call to counterService in the method:

    @Autowired
    private CounterService counterService;

    ...
    public void sampleMethod() {
        counterService.increment

             ("sampleservice.samplemethod.counter");
        ....

    }

If we start the application and access /metrics endpoint, we should see

 "counter.sampleservice.samplemethod.counter":...,

But what if we want to do something more sofisticated, for example, how many times the method was called in the last 5 minutes. Codahale metrics library gives us that functionality and it is integrated with Spring Boot.

You need to add dependency to your pom.xml:

    <dependency>
            <groupId>com.codahale.metrics</groupId>
            <artifactId>metrics-core</artifactId>
    </dependency> 

Then you autowire  MetricRegistry where you want to use metrics:

    @Autowired
    private MetricRegistry metricRegistry;

Now just register the metrics and start using it:

   private Meter meter;

    @PostConstruct
    public void init() {
        meter=metricRegistry.meter("example");
    }

The metrics will show up in the /metrics endpoint:

  "example.fiveMinuteRate": 0,
  "example.oneMinuteRate": 0,
  "example.count": 0,
  "example.fifteenMinuteRate": 0,