Micrometer Dropwizard Bundle

A basic Dropwizard bundle for Micrometer.

About this Repo

The main purpose of this repo is to provide an example of how I have plugged Micrometer to a Dropwizard application. Currently the bundle only supports the capability to expose some JVM metrics of the service in the Prometheus format.

Getting started

Building from Source

To generate and publish in the project directory the jar of the library, run the jar and publish gradle tasks.

./gradlew clean jar publish

A build.sh script is also provided.

Add the MicrometerBundle to your application

Add the MicrometerBundle to your application environment as shown here below:

public class YourApplication extends Application<YourApplicationConfiguration> {
    ...
    
    public void initialize(Bootstrap<YourApplicationConfiguration> bootstrap) {
        MicrometerBundle<ReportsApplicationConfiguration> micrometerBundle = new MicrometerBundle<>(YourApplicationConfiguration::getMicrometerBundleConfiguration);
        bootstrap.addBundle(micrometerBundle);
    }
}

Update the application's configuration class in order to have access to the parameters to configure the MicrometerBundle.

public class YourApplicationConfiguration extends Configuration {

    ...

    @Valid
    @JsonProperty("micrometerBundle")
    private MicrometerBundleConfiguration micrometerBundleConfiguration = new MicrometerBundleConfiguration();

    public MicrometerBundleConfiguration getMicrometerBundleConfiguration() {
        return this.micrometerBundleConfiguration;
    }
}

In the following snippet an example of configuration block for the Prometheus resource to be added to the yml configuration file of your application.

micrometerBundle:
  prometheus:
    path: metrics/prometheus
    name: Metrics in Prometheus format
    prefix: some-prefix
    processorMetricsEnabled: true
    jvmMemoryMetricsEnabled: true
    jvmGcMetricsEnabled: true
    jvmThreadMetricsEnabled: false
    classLoaderMetricsEnabled: false

None of the parameter is mandatory: a default value is always provided. For instance for the path field of the prometheus node the default value is /micrometer/prometheus/. The default value of all the boolean flags is true.

To provide full access to the PrometheusMeterRegistry, the MicrometerBundle exposes a setter and a getter method. A PrometheusMeterRegistryBuilder is also provided in order to facilitate the construction of custom io.micrometer.prometheus.PrometheusMeterRegistry.