Resolve Image to Digest

 1apiVersion: kyverno.io/v1
 2kind: ClusterPolicy
 3metadata:
 4  name: resolve-image-to-digest
 5  annotations:
 6    policies.kyverno.io/title: Resolve Image to Digest
 7    policies.kyverno.io/category: Other
 8    policies.kyverno.io/severity: medium
 9    kyverno.io/kyverno-version: 1.6.0
10    policies.kyverno.io/minversion: 1.6.0
11    kyverno.io/kubernetes-version: "1.23"
12    policies.kyverno.io/subject: Pod
13    policies.kyverno.io/description: >-
14      Image tags are mutable and the change of an image can result in the same tag.
15      This policy resolves the image digest of each image in a container and replaces
16      the image with the fully resolved reference which includes the digest rather than tag.
17spec:
18  background: false
19  rules:
20  - name: resolve-to-digest
21    match:
22      any:
23      - resources:
24          kinds:
25          - Pod
26    preconditions:
27      all:
28      - key: "{{request.operation || 'BACKGROUND'}}"
29        operator: NotEquals
30        value: DELETE
31    mutate:
32      foreach:
33      - list: "request.object.spec.containers"
34        context:
35          - name: resolvedRef
36            imageRegistry:
37              reference: "{{ element.image }}"
38              jmesPath: "resolvedImage"
39        patchStrategicMerge:
40          spec:
41            containers:
42            - name: "{{ element.name }}"           
43              image: "{{ resolvedRef }}"