kyverno/examples/generate/policy_networkPolicy.yaml

apiVersion: kyverno.io/v1alpha1
kind: Policy
metadata:
  name: "default"
spec:
  rules:
  - name: "deny-all-traffic"
    resource: 
      kinds:
       - Namespace
      name: "*"
    generate: 
      kind: NetworkPolicy
      name: deny-all-traffic
      data:
        spec:
        podSelector:
          matchLabels: {}
          matchExpressions: []
        policyTypes: []
        metadata:
          annotations: {}
          labels:
            policyname: "default"