Showing arbitrary @Timed metrics in prometheus

Question

I am trying to add time metrics to my spring-boot web application. Right now, the application uses micrometer, prometheus, and spring-boot-actuator.

I can connect to my app at http://localhost:8080/actuator/prometheus and see the list of default metrics like:

# HELP jvm_gc_memory_allocated_bytes_total Incremented for an increase in the size of the young generation memory pool after one GC to before the next
# TYPE jvm_gc_memory_allocated_bytes_total counter
jvm_gc_memory_allocated_bytes_total{application="my app",} 0.0
# HELP jvm_classes_loaded_classes The number of classes that are currently loaded in the Java virtual machine
# TYPE jvm_classes_loaded_classes gauge
jvm_classes_loaded_classes{application="my app",} 7581.0
...

Awesome!

But now I'd like to attach timing metrics to the methods of one of my controllers. I'd hoped it was as simple as adding an @Timed annotation to the class:

import java.util.concurrent.atomic.AtomicLong;

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

import io.micrometer.core.annotation.Timed;

@RestController
@Timed
public class GreetingController {

    private static final String template = "Hello, %s!";
    private final AtomicLong counter = new AtomicLong();

    @GetMapping("/greeting")
    public Greeting greeting(@RequestParam(value = "name", defaultValue = "World") String name) {
        doWork();
        return buildResponse(name);
    }

    private void doWork() {
        try {
            Thread.sleep((long) (1000 * Math.random()));
        } catch (InterruptedException e) {
        }
    }

    private Greeting buildResponse(String name) {
        return new Greeting(counter.incrementAndGet(), String.format(template, name));
    }
}

However, that doesn't appear to add any metrics to the http://localhost:8080/actuator/prometheus endpoint.

What steps do I need to take in order to have the endpoint report timing metrics of the GreetingController class, and particularly the doWork and buildResponse methods?

-- update --

I've managed to get the results I want but it took a little more work than I was expecting, and I'm hoping that there is an easier way. I explicitly added Timer objects to each method I wanted to measure like so:

import java.util.concurrent.atomic.AtomicLong;
import java.util.concurrent.atomic.AtomicReference;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

import io.micrometer.core.instrument.MeterRegistry;
import io.micrometer.core.instrument.Timer;

@RestController
public class GreetingController {

    private static final String template = "Hello, %s!";
    private final AtomicLong counter = new AtomicLong();

    @Autowired
    MeterRegistry meterRegistry;

    @GetMapping("/greeting")
    public Greeting greeting(@RequestParam(value = "name", defaultValue = "World") String name) {
        doWork();
        return buildResponse(name);
    }

    private void doWork() {
        Timer timer = meterRegistry.timer(this.getClass().getSimpleName() + ".doWork");
        timer.record(() -> {
            try {
                Thread.sleep((long) (1000 * Math.random()));
            } catch (InterruptedException e) {
            }
        });
    }

    private Greeting buildResponse(String name) {
        AtomicReference<Greeting> response = new AtomicReference<>();

        Timer timer = meterRegistry.timer(this.getClass().getSimpleName() + ".buildResponse");
        timer.record(() -> {
            response.set(new Greeting(counter.incrementAndGet(), String.format(template, name)));
        });

        return response.get();
    }
}

But at least this gets me the results I was looking for:

# HELP GreetingController_buildResponse_seconds  
# TYPE GreetingController_buildResponse_seconds summary
GreetingController_buildResponse_seconds_count{application="my app",} 10.0
GreetingController_buildResponse_seconds_sum{application="my app",} 0.001531409
# HELP GreetingController_buildResponse_seconds_max  
# TYPE GreetingController_buildResponse_seconds_max gauge
GreetingController_buildResponse_seconds_max{application="my app",} 2.52253E-4
# HELP GreetingController_doWork_seconds_max  
# TYPE GreetingController_doWork_seconds_max gauge
GreetingController_doWork_seconds_max{application="my app",} 0.941169892
# HELP GreetingController_doWork_seconds  
# TYPE GreetingController_doWork_seconds summary
GreetingController_doWork_seconds_count{application="my app",} 10.0
GreetingController_doWork_seconds_sum{application="my app",} 4.767700907

Is there a cleaner way?

amseager amseager · Accepted Answer · 2020-10-30T18:47:07

Register TimedAspect as a bean in the configuration class:

@Bean
public TimedAspect timedAspect(MeterRegistry meterRegistry) {
    return new TimedAspect(meterRegistry);
}

Showing arbitrary @Timed metrics in prometheus

2 Answers