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========= DC/OS SDK is a collection of tools, libraries, and documentation for easy integration and automation of stateful services, such as databases, message brokers, and caching services.

DC/OS SDK is currently in alpha stage: it can run services, but APIs change regularly, and features are under active development.

Benefits

• Simple and Flexible: The SDK provides the simplicity of a declarative YAML API as well as the flexibility to use the full Java programming language.

• Automate Maintenance: Stateful services need to be maintained. With the SDK, you can automate maintenance routines, such as backup and restore, to simplify operations.

• Available and Durable: When servers fail, you need to reschedule the tasks without data loss or performance impact. With the SDK, you develop automated recovery strategies so services heal themselves.

• Production-Proven: Building reliable services is hard. Uber and Bing platform teams use the SDK for mission-critical databases and message brokers.

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Quick Start

From a workstation with 8G Memory, Git, VirtualBox 5.0.x, and Vagrant 1.8.4, run:

1. Download the DC/OS SDK.

git clone https://github.com/mesosphere/dcos-commons.git

2. Create your local development environment.

cd dcos-commons/ && ./get-dcos-docker.sh

• Visit the DC/OS cluster dashboard to verify your development environment is running.

3. Enter your development environment.

cd tools/vagrant/ && vagrant ssh

4. Build your hello-world example project.

cd /dcos-commons/frameworks/helloworld/ && ./build.sh local

5. Start your hello-world DC/OS service.

dcos package install hello-world

6. Explore your hello-world service.

• Visit the dashboard to see your hello-world service running.
• Click through to one of your tasks (e.g. world-server-1-<uuid>), select the Files tab, select world-container-path, and finally select the output file.

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Understanding the Hello World Service Specification

The service specification declaratively defines the helloworld service:

name: "helloworld"
pods:
  helloworld:
    count: {{COUNT}}
    tasks:
      server:
        goal: RUNNING
        cmd: "echo 'Hello World!' >> helloworld-container-volume/output && sleep 10"
        cpus: {{SERVER_CPU}}
        memory: 32
        volume:
          path: "helloworld-container-volume"
          type: ROOT
          size: 64

In above yaml file, we have:

• Defined a service with the name helloworld
• Configured the service to use ZooKeeper at master.mesos:2181 for storing framework state and configuration.
• Configured the API port using api-port: 8080. By default, each service comes with a default set of useful APIs to enable operationalization.
• Defined a pod specification for our helloworld pod using:

pods:
  helloworld:
    count: {{COUNT}}
    tasks:
      ...

• Declared that we need atleast {{COUNT}} instances of the helloworld pod running at all times, where COUNT is the environment variable that is injected into the scheduler process at launch time via Marathon. It defaults to 1 for this example.
• Defined a task specification for our server task using:

tasks:
  server:
    goal: RUNNING
    cmd: "echo 'Hello World!' >> helloworld-container-volume/output && sleep 10"
    cpus: {{SERVER_CPU}}
    memory: 32

We have configured it to use {{SERVER_CPU}} CPUs (which defaults to 0.5 for this example) and 32 MB of memory.

• And finally, configured a 64 MB persistent volume for our server task where the task data can be persisted using:

volume:
  path: "helloworld-container-volume"
  type: ROOT
  size: 64

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References

• Quick Start Guide - Java
• Developer Guide
• Javadocs

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Contributions

Contributions are welcome! See CONTRIBUTING.

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License

DC/OS SDK is licensed under the Apache License, Version 2.0.