Chapter 6 Docker Swarm

As of Docker 1.12, the Docker Engine provides features to simplify and improve container orchestration for environments deploying multiple identical containers across multiple hosts through a built-in clustering facility. This provides mechanisms to improve load handling and availability. It also helps to reduce or avoid downtime as services are upgraded or replaced, and makes it possible to roll back changes with minimum effort. The engine provides all of the features required to set up a swarm, add and remove nodes to and from the swarm and deploy containers to the swarm. Round-robin load balancing is automatically implemented and failover is handled directly by the swarm.


The Docker Swarm functionality is released as a technology preview for Oracle Linux. As a technology preview, this feature is still under development but is made available for testing and evaluation purposes.

Full documentation for swarm mode within the Docker Engine is provided at

In this chapter, we provide a brief introduction to show how you can start using Docker swarm mode to take advantage of these features immediately. A swarm consists of multiple hosts, each running Docker Engine 1.12 or later. All hosts must be accessible to each other across the same network.