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

Scaling down nodes

One of the benefits of cloud computing is the ability to scale down the number of hosts when they are no longer needed. For example, a web store may increase the number of hosts during the Christmas shopping season and then scale them down in January. How that happens will, again, depend on the orchestration solution chosen and the platform it is running on.

Most orchestration systems have a command that will shut down containers on a specific node and reschedule them elsewhere in the cluster. This gives the orchestration tool a chance to cleanly move services around the cluster before a node is removed. Services such as Docker Cloud and GKE take care of that automatically.

The command to change the node's availability could be added to the shut down scripts. However, care must be made to ensure that all of the containers have stopped before the system is shutdown. In most cases, another command will need to be run to permanently remove a node from the cluster. Again, the...