In other technologies we have clusters, in docker, we have Swarm. Same concept, different name :)

A swarm in docker is set of servers who act as one and each server can be either: Manager or Worked. It is important to note, that manager is also a worked, but the reverse isn't so. Managers manage workers and workers obey, nothing different than clusters.

Below, you can see basic overview of the swarm:

Let's set it up. We will have 5 servers:

• 3 Managers
• 2 Workers