Before we move on, let's take a look at these three concepts in action. Kubernetes ships with a number of examples installed, but we will create a new example from scratch to illustrate some of the concepts.

We already created a pod definition file, but as you learned, there are many advantages to running our pods via replication controllers. Again, using the book-examples/02_example folder we made earlier, we will create some definition files and start a cluster of Node.js servers using a replication controller approach. Additionally, we'll add a public face to it with a load-balanced service.

Use your favorite editor to create the following file:

apiVersion: v1 
kind: ReplicationController 
metadata: 
  name: node-js 
  labels: 
    name: node-js 
spec: 
  replicas: 3 
  selector: 
    name: node-js 
  template: 
    metadata: 
      labels: 
        name: node-js 
    spec: 
     ...