kyverno/samples/best_practices/trusted_image_registries.yaml

apiVersion : kyverno.io/v1alpha1
kind: ClusterPolicy
metadata:
  name: trusted-registries
spec:
  rules:
  - name: trusted-registries
    match:
      resources:
        kinds:
        - Pod
    validate:
      message: "Deny untrusted registries"
      pattern:
        spec:
          containers:
          - image: "k8s.gcr.io/* | gcr.io/*"