ReplicaSet fails with invalid: spec.template.metadata.labels

Question

I am trying to do some research on replicaSet for my learning purpose. I was able to create a replicaSet successfully with matchLabels. To test the matchExpression selector, I c

Answer 1

Can you try with the following by changing the label in template section.

apiVersion: apps/v1
kind: ReplicaSet
metadata:
  name: replicaset-2
spec:
  replicas: 2
  selector:
    matchExpressions:
      - {key: tier, operator: In, values: [frontend1]}
  template:
    metadata:
      labels:
        tier: frontend1
    spec:
      containers:
      - name: nginx
        image: nginx

Answer 2

To make pod fall into newly created ReplicaSet's scope using matchExpressions you have to either use the same labels in RS as defined in already created pod or you have to add additional label in the expression so it looks like following:

apiVersion: apps/v1
kind: ReplicaSet
metadata:
  name: replicaset-2
spec:
  replicas: 2
  selector:
    matchExpressions:
    - key: tier
      operator: In
      values:
      - frontend1
      - nginx
  template:
    metadata:
      labels:
        tier: nginx
    spec:
      containers:
      - name: nginx
        image: nginx

This way RS will recognize already existing pod as its own and create only one more pod to meet the requirements defined in replicas field.