Dropwizard and Friends

On a Twelve-factor Quest

Sydney MicroServices Meetup April 2015

About Me

• Comp Science Bachelor UNSW
• Applied Finance PostGrad at Macquarie Uni
• ESB driver at Accenture, BGI/BlackRock, Macquarie Group
• Now Microservicing Trunk Platform

yunspace

yunzhilin

yunspace.com

• My opinions does not reflect the view of the company
• Shout out if you have questions, or answers

Why Dropwizard?

Standalone App

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

java -jar build/awesome_api.jar server awesome_api.yml

Builds and runs a Fat Jar

Start Application in a simple Main() method

Who Uses Dropwizard?

• Sky - Fault Tolerant Microservices
• Datasift - dropwizard extra, scala, zeromq
• HubSpot - dropwizard-guice
• Gilt - Production Ready Web Services with Dropwizard
• airbnb - Introducing Airpal
• Riot Games - How we built a Cloud Platform at Riot Games using NetflixOSS
• Bloom Health - Micro-services with Dropwizard

Surely Java without App Server is unstable?

Production Ready

• Ops Friend
• Health Checks
• Metrix

More so than most Enterprise Apps

Plays Well with Others

• More Modules at http://modules.dropwizard.io/

Easy to do the Right Thing

Dropwizard makes it easy to do the right thing, allowing you to concentrate on the essential complexity of a problem rather than the plumbing

ThoughtWorks Technology Radar

High

Performance

techempower.com/benchmarks/

Low

Latency

techempower.com/benchmarks/

Compared to Rails

Dropping Rails for Dropwizard? - Yammer, April 2014

Compared Spring Boot

Java BootStrap: Dropwizard vs SprintBoot - Takipi Blog

Compared to RatPack

public class FooBarFactory implements HandlerFactory {

  @Override
  public Handler create(LaunchConfig launchConfig) throws Exception {
    return Guice.builder(launchConfig)
      .bindings(bindingsSpec -> bindingsSpec.add(new MyModule()))
      .build(chain -> chain
        .handler("foo", context -> context.render("from the foo handler"))
        .handler("bar", context -> context.render("from the bar handler")));
    }
}

public class FooBarApplication extends Application<FooBarConfig> {
  
  public static void main(String[] args) throws Exception {
    new FooBarApplication().run(args);
  }
  
  @Override
  public void run(final FooBarApplication configuration, final Environment environment) throws Exception {
    environment.register(FooResource.class);
    environment.register(BarResrouce.class);
  }
}

@Path("/foo")
@Consumes(APPLICATION_JSON) @Produces(APPLICATION_JSON)
public class FooResource {
  @GET
  public String getFoo() {
    return "from the foo handler";
  }
}

• Dropwizard is more opinionated and explicit

Right Tool for the Right Job

• Not a silver bullet
• We also use Rails to leverage neat Gems
• And AngularJs on HarpJs for Static Sites

Build another "Hello World" App?

Demo

Let's build a Dropwizard Turbo app using LazyBones!

12 Factors

Design Decisions

Iron Fisted

Gradle

Declare and isolate Dependencies (II)

Portable "gradlew" is great for CI & locks gradle version

More than just Dependency Management:

• builds shadow

Configuration

• Configuration using Environment Variables (III)
• Attach Backing Services (IV) with no code change

Modules

• Dropwizard version 0.8.0: Jersey2 major update.
• github.com/dropwizard/dropwizard-java8
• github.com/hubspot/dropwizard-guice
• We are active contributors, get in contact if you have any issues

Used by lazybones-dropwizard-turbo

Swagger.IO

Integration using our own code

New Relic

• Gist: NewRelicTimedApplicationListener
• Register above listener, add newrelic.jar

Dockerfile

FROM errordeveloper/oracle-jre

ENV HOME /root/
WORKDIR /app/

# newrelic
RUN curl -L --silent --retry 3 \
    https://download.newrelic.com/newrelic/java-agent/newrelic-agent/current/newrelic-java.zip -o newrelic-java.zip
RUN unzip newrelic-java.zip && \
    rm newrelic/*.xml newrelic/*.xsd newrelic/*.yml newrelic/newrelic-api*.jar
ADD newrelic/newrelic.yml /app/newrelic/newrelic.yml

# plamasphere
ADD platmasphere-services.yml /app/
ENV PLATMA_VERSION latest
ADD build/platmasphere-services.jar /app/platmasphere-services.jar

# run
EXPOSE 9090
ENTRYPOINT [ "java" ]
CMD ["-javaagent:newrelic/newrelic.jar", "-jar", "platmasphere-services.jar", "server", "platmasphere-services.yml"]

Tips

• Joda DateTime is NOT equivalent to JSR-310 LocalDateTime. Use ZonedDateTime or OffsetDateTime

compile "org.jadira.usertype:usertype.extended:3.2.0.GA"

• Use Governator @LazySingleton if you have issue with Guice eager @Singleton

    compile("com.netflix.governator:governator:${governatorVersion}") {
        exclude group: 'com.google.guava', module: 'guava'
        exclude group: 'commons-lang'
    }

• Multiple Database Schema Support: have a look here

• Jadira UserType Extended for Hibernate JSR-310 support

Continuous Delivery

+

Docker

Snap-CI

Continuous Delivery enables:

• Strictly Separate Build, Release, Run (V)
• Reduced Dev/prod parity (X)

Pact Contract 

{
  "description": "request for getting property 80 CLARENCE ST",
  "provider_state": "property 80 CLARENCE ST exists",
  "request": {
    "method": "get",
    "path": "/properties/1",
    "headers": {
      "Tenant": "trunk",
      "Authorization": "Bearer valid_token"
    }
  },
  "response": {
    "status": 200,
    "headers": {
      "Access-Control-Allow-Origin": "*",
      "Access-Control-Allow-Headers": "origin, content-type, accept, authorization, tenant",
      "Access-Control-Allow-Credentials": "true",
      "Access-Control-Allow-Methods": "GET, POST, PUT, DELETE, OPTIONS, HEAD",
      "Access-Control-Max-Age": "43200"
    },
    "body": {
      "id": 1,
      "addressLine": "80 CLARENCE ST",
      "postcode": "2000",
      "state": "NSW",
      "suburb": "SYDNEY",
      "streamId": 1
    }
  }
}

BinTray and Quay.io

One Codebase, many deploys (I)

• Small Base Image = quicker build time
• Use errordeveloper/oracle-jre (busybox based)
• Only 159 mb

Build Docker Images

Database Migration

Prior to deploying to a Environment, we run DB Migration as Once off Admin Processes (XII) 

./gradlew dbMigrate -Pdb_schema=
./gradlew dbTag -Pdb_schema=

Deploy Docker Container

• Isolation of Stateless Processes (VI) and Port binding (VII)
• Containers are Disposable(IX) and Concurrent(VIII)
• Stream Logs (XI) to LogSpout

Docker Containers takes care of:

Running Containers in Tutum

https://docs.tutum.co/v2/api/