Deployment

A Deployment is a Kubernetes object that acts as a wrapper around a ReplicaSet and makes it easier to use. In general, in order to manage replicated services, it's recommended that you use Deployments that, in turn, manage the ReplicaSet and the Pods created by the ReplicaSet.

The major motivation for using a Deployment is that it maintains a history of revisions. Every time a change is made to the ReplicaSet or the underlying Pods, a new revision of the ReplicaSet is recorded by the Deployment. This way, using a Deployment makes it easy to roll back to a previous state or version. Keep in mind that every rollback will also create a new revision for the Deployment. The following diagram provides an overview of the hierarchy of the different objects managing your containerized application:

Figure 7.6: Hierarchy of Deployment, ReplicaSet, Pods, and containers

Deployment Configuration

The configuration of a Deployment is actually very similar...