Dropwizard

public class DemoApplication extends Application<DemoConfiguration> {
    public static void main(String[] args) throws Exception {
        new DemoApplication().run(args);
    }

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

    @Override
    public void run(DemoConfiguration configuration,
                    Environment environment) throws Exception {
    }
}

public void initialize(Bootstrap<DemoConfiguration> bootstrap) {
    bootstrap.addBundle(...);
    bootstrap.addCommand(...);
}

public void run(DemoConfiguration configuration,
                Environment environment) throws Exception {
    environment.jersey().register(EchoResource.class);
    environment.lifecycle().manage(...);
    environment.healthChecks().register("demo-health", ...);
    environment.admin().addTask(...);
}

public class DemoConfiguration extends Configuration {
    @NotBlank
    private String customSetting;

    public String getCustomSetting() {
        return customSetting;
    }
}

@Path("/echo")
@Produces(MediaType.TEXT_PLAIN)
public class EchoResource {
    @GET
    @Timed
    public String echo(@QueryParam("message")
                       @NotBlank
                       String message) {
        return message;
    }
}

@ClassRule
public static final ResourceTestRule resources =
        ResourceTestRule.builder()
                .addResource(new PingResource())
                .build();

@Test
public void testPingPong() throws Exception {
    final Pong expectedPong = ImmutablePong.builder()
            .message("pong")
            .build();
    final Pong actualPong = resources.client().target("/ping")
            .request()
            .get(Pong.class);

    assertEquals(expectedPong, actualPong);
}

@ClassRule
public static final DropwizardAppRule<DemoConfiguration> RULE =
        new DropwizardAppRule<>(
                DemoApplication.class,
                ResourceHelpers.resourceFilePath("demo_test.yml"));

@Test
public void testListKittens() throws IOException {
    final Client client = ClientBuilder.newClient();
    final Collection<Kitten> kittens = client
            .target(String.format("http://localhost:%d/kittens/", RULE.getLocalPort()))
            .request(MediaType.APPLICATION_JSON)
            .get(new GenericType<Collection<Kitten>>() {});

    assertEquals(1, kittens.size());
    assertEquals("Findus", Iterables.getOnlyElement(kittens).getName());
}

protected Result check() throws Exception {
    if (store.isRunning()) {
        return Result.healthy("Store is OK.");
    } else {
        return Result.unhealthy("Store is offline.");
    }
}

{
  "deadlocks" : {
    "healthy" : true
  },
  "demo-health" : {
    "healthy" : true,
    "message" : "Everything is fine. :)"
  },
  "store-health" : {
    "healthy" : true,
    "message" : "Store is OK."
  }
}

public void execute(ImmutableMultimap<String, String> parameters,
                    PrintWriter output) throws Exception {
    output.println(parameters);
}

$ curl -X POST \
  'http://localhost:8080/admin/tasks/echo?param=value1&param=value2'
{param=[value1, value2]}

protected void run(Bootstrap<DemoConfiguration> bootstrap,
                   Namespace namespace,
                   DemoConfiguration configuration) throws Exception {
    System.out.format(
            Locale.ENGLISH,
            "Hi! This demo is presented by %s in %d.\n",
            configuration.getSpeakerName(),
            configuration.getYear());
}

$ java -jar build/libs/demo-1.0.0-SNAPSHOT-all.jar greet config.yml
Hi! This demo is presented by Jochen Schalanda in 2017.

$ java -jar build/libs/demo-1.0.0-SNAPSHOT-all.jar check config.yml
INFO  [2017-01-11 15:02:26,269] io.dropwizard.cli.CheckCommand:
Configuration is OK

$ java -jar build/libs/demo-1.0.0-SNAPSHOT-all.jar check config.yml
config.yml has an error:
  * Unrecognized field at: spiekerName
    Did you mean?:
      - speakerName

{
  "com.example.demo.resource.PingResource.pingPong" : {
    "count" : 6,
    "m15_rate" : 1.0,
    "m1_rate" : 1.0,
    "m5_rate" : 1.0,
    "mean_rate" : 0.7386288754923656,
    "units" : "events/second"
  }
}