kyverno/examples/Validate/check_image_version.yaml

apiVersion : kyverno.nirmata.io/v1alpha1
kind: Policy
metadata:
  name: image-pull-policy
spec:
  rules:
  - name: image-pull-policy
    message: "Image tag ':latest' requires imagePullPolicy 'Always'"
    resource:
      kinds: 
      - Deployment
    overlay:
      template:
        spec:
          containers:              
            - image: "(*:latest)"       # select images which end with :latest            
              imagePullPolicy: "Always" # ensure that the imagePullPolicy is "Always"