replicaset-definition.yml

apiVersion: apps/v1
kind: ReplicaSet
metadata:
  name: myapp-replicaset
  labels:
    app: myapp
    type: front-end
spec:
  # spec defines whats inside this object
  # here the replica set creates multiple instances of a pod
  # we create a template section under spec to provide a pod template
  # ... to be used by the replica set to create replicas
  template:
    # here what we are going to do is to get the metadata and spec sections of the pod-definition file
    metadata:
      name: myapp-pod
      labels:
        app: myapp
        type: front-end
    spec:
      containers:
        - name: nginx-container
          image: nginx
  # inputting the number of  replicas that we need to create from the pod template.
  replicas: 3
  # replicaSet requires a selector sections
  # helps to identify what pods fall under the replica set
  # this is because replica sets can also manage pods that are not created as a part of the replica set creation process
  # for example there might be pods that are created before that replica set creation.
  selector:
    # matchLabels is used to match the labels of the pods
    # all the pods that have the same labels will be managed by the replica set
    matchLabels:
      type: front-end