The Docker Swarm architecture

The architecture of a Docker Swarm from a 30,000-foot view consists of two main parts—a raft consensus group of an odd number of manager nodes, and a group of worker nodes that communicate with each other over a gossip network, also called the control plane. The following diagram illustrates this architecture:

Figure 14.1 – High-level architecture of a Docker Swarm

The manager nodes manage the swarm while the worker nodes execute the applications deployed into the swarm. Each manager has a complete copy of the full state of the Swarm in its local raft store. Managers synchronously communicate with each other, and their raft stores are always in sync.

The workers, on the other hand, communicate with each other asynchronously for scalability reasons. There can be hundreds if not thousands of worker nodes in a Swarm.

Now that we have a high-level overview of what a Docker Swarm is, let’s describe all...