Replica sets

As discussed earlier, replica sets are the new and improved version of replication controllers. They take advantage of set-based label selection, but they are still considered beta at time of this writing.
Here is an example of a ReplicaSet based on and similar to the ReplicationController in listing 2-4:

apiVersion: extensions/v1beta1 
kind: ReplicaSet 
metadata: 
  name: node-js-rs 
spec: 
  replicas: 3 
  selector: 
    matchLabels: 
      app: node-js-express 
      deployment: test 
    matchExpressions: 
      - {key: name, operator: In, values: [node-js-rs]} 
  template: 
    metadata: 
      labels: 
        name: node-js-rs 
        app: node-js-express 
        deployment: test 
    spec: 
      containers: 
      - name: node-js-rs 
        image: jonbaier/node-express-info:latest 
        ports: 
        - containerPort: 80

Listing 2-6: nodejs-labels-replicaset.yaml