Deploying an Application

Using the kubectl create command, we can quickly deploy an application. We have looked at the Pods created running the application, like nginx. Looking closer, you will find that a Deployment was created, which manages a ReplicaSet, which then deploys the Pod.

Let's take a closer look at each object.

Objects

Deployment

It is a controller which manages the state of ReplicaSets and the pods within. The higher level control allows for more flexibility with upgrades and administration. Unless you have a good reason, use a deployment.

ReplicaSet

Orchestrates individual pod lifecycle and updates. These are newer versions of Replication Controllers, which differ only in selector support.

Pod

As we've already mentioned, it is the lowest unit we can manage; it runs the application container, and possibly support containers.