We have mentioned the Swarm mode briefly in the Chapter 4, Networking and Persistent Storage, when we were learning about multi-host networks. This time, we will look closer to the container clustering features of Docker. The Swarm mode is quite new feature in Docker - it's available in Docker version 1.12 and up. It means, that you can only use this in Linux, which is obvious, but if you run Docker in Windows or Mac, you can use the native Docker for Windows or Docker for Mac application. However, what Swarm is? Let's explain what was the purpose behind including the Swarm in latest Docker versions.
Running a single application in a Docker container is easy. We already did it a number of times. But what about scaling and fail-over? Imagine that you have an application or service that will need to respond swiftly even under heavy load. If a single container cannot handle the load, then you will probably want to run multiple containers. Using Docker Swarm, you...