Book Image

Docker Orchestration

By : Randall Smith
Book Image

Docker Orchestration

By: Randall Smith

Overview of this book

Docker orchestration is what you need when transitioning from deploying containers individually on a single host to deploying complex multi-container apps on many machines. This book covers the new orchestration features of Docker 1.12 and helps you efficiently build, test, and deploy your application using Docker. You will be shown how to build multi-container applications using Docker Compose. You will also be introduced to the building blocks for multi-host Docker clusters such as registry, overlay networks, and shared storage using practical examples. This book gives an overview of core tools such as Docker Machine, Swarm, and Compose which will enhance your orchestration skills. You’ll learn how to set up a swarm using the decentralized building block. Next, you’ll be shown how to make the most out of the in-built orchestration feature of Docker engine and you’ll use third-party tools such as Kubernetes, Mesosphere, and CoreOS to orchestrate your existing process. Finally, you will learn to deploy cluster hosts on cloud services and automate your infrastructure.
Table of Contents (17 chapters)
Docker Orchestration
About the Author
About the Reviewer
Customer Feedback

Managing applications

A Mesos cluster is managed with the dcos tool and the web interface. Applications in Mesos are handled by the Marathon scheduler and are defined in JSON format.

Running a simple application

Let's start with a simple container that runs Nginx. Create a file named nginx.json that contains the following definition:

  "id" : "simple-nginx", 
  "instances" : 1, 
  "cpus" : 0.25, 
  "mem" : 64.0, 
  "container" : { 
    "type" : "DOCKER", 
    "docker" : { 
      "image" : "nginx:1.11", 
      "network" : "HOST" 

The id tag is the name of the service. It is displayed in the service list. The instances tag tells Marathon that only one instance is needed. It can be increased or decreased as needed later.

The cpus and mem tags are hints to Marathon as to what percentage of CPU and the amount of RAM is needed. They do not actually set resource limits in Docker. However, Marathon may kill tasks that...