Splitting the Pod and establishing communication through Services

Let's take a look at a ReplicaSet definition for a Pod with only the database:

cat svc/go-demo-2-db-rs.yml  

The output is as follows:

apiVersion: apps/v1beta2
kind: ReplicaSet
metadata:
  name: go-demo-2-db
spec:
  selector:
    matchLabels:
      type: db
      service: go-demo-2
  template:
    metadata:
      labels:
        type: db
        service: go-demo-2
        vendor: MongoLabs
    spec:
      containers:
      - name: db
        image: mongo:3.3
        ports:
        - containerPort: 28017  

We'll comment only on the things that changed.

Since this ReplicaSet defines only the database, we reduced the number of replicas to 1. Truth be told, MongoDB should be scaled as well, but that's out of the scope of this chapter (and probably the book as well). For now, we'll pretend that one...