Dropwizard-Guice

A simple DropWizard extension for integrating Guice via a bundle. It optionally uses classpath scanning courtesy of the Reflections project to discover resources and more to install into the dropwizard environment upon service start.

Usage

    <dependencies>
        <dependency>
            <groupId>com.hubspot.dropwizard</groupId>
            <artifactId>dropwizard-guice</artifactId>
            <version>${current.version}</version>
        </dependency>
    </dependencies>

A list of available versions can be found at https://github.com/HubSpot/dropwizard-guice/releases

Simply install a new instance of the bundle during your service initialization

public class HelloWorldApplication extends Application<HelloWorldConfiguration> {

  private GuiceBundle<HelloWorldConfiguration> guiceBundle;

  public static void main(String[] args) throws Exception {
    new HelloWorldApplication().run(args);
  }

  @Override
  public void initialize(Bootstrap<HelloWorldConfiguration> bootstrap) {

    guiceBundle = GuiceBundle.<HelloWorldConfiguration>newBuilder()
      .addModule(new HelloWorldModule())
      .setConfigClass(HelloWorldConfiguration.class)
      .build();

    bootstrap.addBundle(guiceBundle);
  }

  @Override
  public String getName() {
    return "hello-world";
  }

  @Override
  public void run(HelloWorldConfiguration helloWorldConfiguration, Environment environment) throws Exception {
    environment.jersey().register(HelloWorldResource.class);
    environment.lifecycle().manage(guiceBundle.getInjector().getInstance(TemplateHealthCheck.class));
  }
}

Auto Configuration

You can enable auto configuration via package scanning.

public class HelloWorldApplication extends Application<HelloWorldConfiguration> {

  public static void main(String[] args) throws Exception {
    new HelloWorldApplication().run(args);
  }

  @Override
  public void initialize(Bootstrap<HelloWorldConfiguration> bootstrap) {

    GuiceBundle<HelloWorldConfiguration> guiceBundle = GuiceBundle.<HelloWorldConfiguration>newBuilder()
      .addModule(new HelloWorldModule())
      .enableAutoConfig(getClass().getPackage().getName())
      .setConfigClass(HelloWorldConfiguration.class)
      .build();

    bootstrap.addBundle(guiceBundle);
  }

  @Override
  public String getName() {
    return "hello-world";
  }

  @Override
  public void run(HelloWorldConfiguration helloWorldConfiguration, Environment environment) throws Exception {
    // now you don't need to add resources, tasks, healthchecks or providers
    // you must have your health checks inherit from InjectableHealthCheck in order for them to be injected
  }
}

Dropwizard Task requires a TaskName. Therefore when Auto Configuring a Task, you need to inject in the TaskName:

@Singleton
public class MyTask extends Task {

    @Inject
    protected MyTask(@Named("MyTaskName") String name) {
        super(name);
    }

    @Override
    public void execute(ImmutableMultimap<String, String> immutableMultimap, PrintWriter printWriter) throws Exception {

    }
}

And bind the TaskName in your module:

bindConstant().annotatedWith(Names.named("MyTaskName")).to("my awesome task");

See the test cases: InjectedTask and TestModule for more details.

Environment and Configuration

If you are having trouble accessing your Configuration or Environment inside a Guice Module, you could try using a provider.

public class HelloWorldModule extends AbstractModule {

  @Override
  protected void configure() {
    // anything you'd like to configure
  }

  @Provides
  public SomePool providesSomethingThatNeedsConfiguration(HelloWorldConfiguration configuration) {
    return new SomePool(configuration.getPoolName());
  }

  @Provides
  public SomeManager providesSomenthingThatNeedsEnvironment(Environment env) {
    return new SomeManager(env.getSomethingFromHere()));
  }
}

Injector Factory

You can also replace the default Guice Injector by implementing your own InjectorFactory. For example if you want to use Governator, you can set the following InjectorFactory (using Java 8 Lambda) when initializing the GuiceBundle:

@Override
public void initialize(Bootstrap<HelloWorldConfiguration> bootstrap) {

  GuiceBundle<HelloWorldConfiguration> guiceBundle = GuiceBundle.<HelloWorldConfiguration>newBuilder()
    .addModule(new HelloWorldModule())
    .enableAutoConfig(getClass().getPackage().getName())
    .setConfigClass(HelloWorldConfiguration.class)
    .setInjectorFactory((stage, modules) -> LifecycleInjector.builder()
        .inStage(stage)
        .withModules(modules)
        .build()
        .createInjector()))
    .build();

 bootstrap.addBundle(guiceBundle);
}

Testing

As of Dropwizard 0.8.x, when writing Integration Tests using DropwizardAppRule, you need to reset jersey2-guice by running:

JerseyGuiceUtils.reset();

Examples

Please fork an example project if you'd like to get going right away.

You may also find more updated and comprehensive examples in the test cases.

Enjoy!

travisp / dropwizard-guice