This policy validates the labels of generic Kubernetes objects.

The policy rejects all the resources that use one or more labels on the deny list. The deny list is provided at runtime via the policy configuration.

The policy allows users to put constraints on specific labels. The constraints are expressed as regular expression and are provided via the policy settings.

The policy allows users to require specific labels to be part of the resource. The list of mandatory labels is provided at runtime via the policy configuration.

The policy settings look like that:

# List of labels that cannot be used
denied_labels:
- foo
- bar

# List of labels that must be defined
mandatory_labels:
- cost-center

# Labels that are validate with user-defined RegExp
# Failing to comply with the RegExp resuls in the object
# being rejected
constrained_labels:
  priority: "[123]"
  cost-center: "^cc-\\d+$"

Note well: the regular expression must be expressed using Go's syntax.

Given the configuration from above, the policy would reject the creation of this Pod:

apiVersion: v1
kind: Pod
metadata:
  name: nginx
  labels:
    foo: hello world
spec:
  containers:
    - name: nginx
      image: nginx:latest

The policy would also reject the creation of this Ingress resource:

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: minimal-ingress
  labels:
    cost-center: cc-marketing
  annotations:
    nginx.ingress.kubernetes.io/rewrite-target: /
spec:
  rules:
  - http:
      paths:
      - path: /testpath
        pathType: Prefix
        backend:
          service:
            name: test
            port:
              number: 80