Add Default Resources

apiVersion: kyverno.io/v1
kind: ClusterPolicy
metadata:
  name: add-default-resources
  annotations:
    policies.kyverno.io/title: Add Default Resources
    policies.kyverno.io/category: Other
    policies.kyverno.io/severity: medium
    kyverno.io/kyverno-version: 1.10.0-alpha.2
    policies.kyverno.io/minversion: 1.7.0
    kyverno.io/kubernetes-version: "1.26"
    policies.kyverno.io/subject: Pod
    policies.kyverno.io/description: Pods which don't specify at least resource requests are assigned a QoS class of BestEffort which can hog resources for other Pods on Nodes. At a minimum, all Pods should specify resource requests in order to be labeled as the QoS class Burstable. This sample mutates any container in a Pod which doesn't specify memory or cpu requests to apply some sane defaults.
spec:
  background: false
  rules:
    - name: add-default-requests
      match:
        any:
          - resources:
              kinds:
                - Pod
      preconditions:
        any:
          - key: "{{request.operation || 'BACKGROUND'}}"
            operator: AnyIn
            value:
              - CREATE
              - UPDATE
      mutate:
        foreach:
          - list: request.object.spec.[ephemeralContainers, initContainers, containers][]
            patchStrategicMerge:
              spec:
                containers:
                  - (name): "{{element.name}}"
                    resources:
                      requests:
                        +(memory): 100Mi
                        +(cpu): 100m