In this chapter, we met the new actors in the Docker ecosystem: SwarmKit and Swarm Mode. We proceeded through a simple implementation of a SwarmKit cluster with Ansible on Amazon AWS. Then, we covered the essential concepts of Swarm Mode, introducing its interface and its internals, including DNS, load balancing, services, replicas, and the promotion/demotion mechanism. Now, it's time to dive into a true Swarm Mode deployment, as we'll see in Chapter 4, Creating a Production-Grade Swarm.