This project integrates Dropwizard, a Java web service framework, with Apache Helix, a cluster management framework for partitioned and replicated distributed resources.

To include this library in your project, add the following dependency

<dependency>
  <groupId>com.github.brandtg</groupId>
  <artifactId>dropwizard-helix</artifactId>
  <version>0.0.1</version>
</dependency>

A very simple use case is service discovery. In Helix terms, we model each service as a Cluster, and services are Instances within that cluster.

First, add the bundle in your Application's initialize method, e.g.:

public static class SimpleServer extends Application<SimpleServerConfiguration> {

    @Override
    public void initialize(Bootstrap<SimpleServerConfiguration> bootstrap) {
      bootstrap.addBundle(new HelixServiceDiscoveryBundle<SimpleServerConfiguration>() {
        @Override
        protected HelixServiceDiscoveryConfiguration
        getHelixServiceDiscoveryBundleConfiguration(SimpleServerConfiguration configuration) {
          return configuration.getHelix();
        }
      });
    }
    
    ...
}

Finally, add the following to your server config (substituting your zkAddress and clusterName):

helix:
    zkAddress: 'localhost:2181'
    clusterName: 'MY_SERVICE'

The Helix Instance name is derived from the host name the machine is running on, and the first Dropwizard application connector. E.g. myhost-123.mycompany.com_10000

In your client code, you can use HelixServiceDiscoverer to find the application socket addresses:

// Create and start discovery class (connect to ZK)
HelixServiceDiscoverer discoverer = new HelixServiceDiscoverer("localhost:2181", "MY_SERVICE");
discoverer.start();

// Get all services
List<InetSocketAddress> services = discoverer.getServices();

// Get a random service
InetSocketAddress service = discoverer.getService();

// Disconnect from ZK
discoverer.stop();

This class implements Managed, so be sure to add the following in your application's lifecycle:

environment.lifecycle().manage(discoverer);

If this is done, #start and #stop methods do not need to be called.