# k8s_docs_deployment-replicas-policy.yaml
apiVersion: admissionregistration.k8s.io/v1
kind: ValidatingAdmissionPolicy
metadata:
  name: "deploy-replica-policy.example.com"
spec:
  paramKind:
    apiVersion: rules.example.com/v1
    kind: ReplicaLimit
  matchConstraints:
    resourceRules:
    - apiGroups:   ["apps"]
      apiVersions: ["v1"]
      operations:  ["CREATE", "UPDATE"]
      resources:   ["deployments"]
  validations:
  - expression: "object.spec.replicas <= params.maxReplicas"
    messageExpression: "'object.spec.replicas must be no greater than ' + string(params.maxReplicas)"
    reason: Invalid