如何向 Prometheus 公开 Dropwizard 指标

Question

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I would like to see the minimal but working example of application which can generate metrics(using dropwizard) and provides endpoint which will return metrics in format ready to be consumed by Prometheus

I have implemented a Java web service using Dropwizard . Now I want it to also expose Prometheus metrics .

I have followed this pretty straight-forward example. However, the endpoint at http://localhost:9090/metrics is still not exposed.

Here's the relevant code:

Dependencies in the pom.xml :

    <dependency>
        <groupId>io.prometheus</groupId>
        <artifactId>simpleclient_dropwizard</artifactId>
        <version>0.5.0</version>
    </dependency>
    <!-- https://mvnrepository.com/artifact/io.prometheus/simpleclient_servlet -->
    <dependency>
        <groupId>io.prometheus</groupId>
        <artifactId>simpleclient_servlet</artifactId>
        <version>0.5.0</version>
    </dependency>

The Java code:

import io.dropwizard.Application;
import io.dropwizard.setup.Bootstrap;
import io.dropwizard.setup.Environment;
import io.prometheus.client.CollectorRegistry;
import io.prometheus.client.dropwizard.DropwizardExports;
import io.prometheus.client.exporter.MetricsServlet;
[...]

public class MyApplication extends Application<MyServiceConfiguration> {

@Override
public void run(final MyServiceConfiguration configuration,
        final Environment environment) {
    final MyServiceResource resource = createResource(configuration);
    environment.jersey().register(resource);

    registerHealthChecks(environment, resource);

    registerMetrics(environment);
}

private void registerMetrics(Environment environment) {
    CollectorRegistry collectorRegistry = new CollectorRegistry();
    collectorRegistry.register(new DropwizardExports(environment.metrics()));
    environment.admin().addServlet("metrics", new MetricsServlet(collectorRegistry))
            .addMapping("/metrics");
}

Any pointers to what I'm doing wrong?

Answer 1

Remember default dropwizard configuration has the admin app on a different port. That's where you'd find the metrics servlet.