apiVersion: kyverno.io/v1
kind: ClusterPolicy
metadata:
  name: max-containers
spec:
  validationFailureAction: Enforce
  background: false
  rules:
  - name: max-two-containers
    match:
      any:
      - resources:
          kinds:
          - Pod
    validate:
      message: "A maximum of 2 containers are allowed inside a Pod."
      deny:
        conditions:
          any:
          - key: "{{request.object.spec.containers[] | length(@)}}"
            operator: GreaterThan
            value: "2"