Kubernetes Deployments

Kubernetes takes the single-responsibility principle very seriously. All Kubernetes objects are designed to do one thing and one thing only, and they are designed to do this one thing very well. In this regard, we must understand Kubernetes ReplicaSets and Deployments. A ReplicaSet, as we have learned, is responsible for achieving and reconciling the desired state of an application service. This means that the ReplicaSet manages a set of pods.

A Deployment augments a ReplicaSet by providing rolling updates and rollback functionality on top of it. In Docker Swarm, the Swarm service incorporates the functionality of both a ReplicaSet and Deployment. In this regard, SwarmKit is much more monolithic than Kubernetes. The following diagram shows the relationship of a Deployment to a ReplicaSet:

Figure 16.21 – Kubernetes Deployment

In the preceding diagram, the ReplicaSet defines and governs a set of identical pods. The main characteristics...