If you've an existing instrumentation library in use, it's not always practical to immediately switch to a Prometheus instrumentation library. There are a multitude of integrations available to aid your transition.

Dropwizard metrics is a popular instrumentation library for the JVM. While it lacks labels and tends to do calculations in the client rather than exposing the raw counters that Prometheus prefers, you may wish to use what you already have while you're still busy porting instrumentation over to the Prometheus Java client.

The good news is that integrating the two instrumentation systems is only a few of lines of code. I'll presume you already have both the Prometheus and Dropwizard client libraries setup and working inside your application.

Add the simpleclient_dropwizard module to your pom.xml , or equivalent:

<dependency> <groupId>io.prometheus</groupId> <artifactId>simpleclient_dropwizard</artifactId> <version>0.0.23</version> </dependency>

And then the following code:

import io.prometheus.client.CollectorRegistry; import io.prometheus.client.dropwizard.DropwizardExports; // Inside an initialisation function. CollectorRegistry.defaultRegistry.register(new DropwizardExports(metrics));

Where metrics is a Dropwizard MetricsRegistry . And that's it!

A complete working example can be found on Github.

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