Unique ingress host

This policy prevents the creation of Ingress resources that have host rules conflicting with the Ingress objects already defined inside of the cluster.

Note: this policy does not handle hostname wildcards.

Access to Kubernetes resources

This policy requires access to networking.k8s.io/Ingress objects. Access has to be granted at deployment time by setting the contextAwareResources attribute of the ClusterAdmissionPolicy.

Note: context aware policies cannot be deployed using the AdmissionPolicy custom resource.

Refer to the context aware documentation for more details.

Settings

This policy does not take any configuration value.

This is a Gatekeeper policy that prevents the creation of Ingress resources with duplicated hosts.

Example

Assume the following Ingress object already exists inside of the cluster:

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: already-exists
spec:
  rules:
    - host: "example.com"
      http:
        paths:
          - pathType: Prefix
            path: "/foo"
            backend:
              service:
                name: service1
                port:
                  number: 80

The policy would allow the creation of this new Ingress object:

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: new-one
spec:
  rules:
    - host: "esempio.it"
      http:
        paths:
          - pathType: Prefix
            path: "/foo"
            backend:
              service:
                name: service2
                port:
                  number: 80

While it would deny the creation of this one:

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: not-valid
spec:
  rules:
    - host: "example.com"
      http:
        paths:
          - pathType: Prefix
            path: "/foo"
            backend:
              service:
                name: service3
                port:
                  number: 80

The latter object is not allowed because its host rule overlaps with the one of the already-exists Ingress.

Implementation details

The policy is a 1:1 copy of this one, it's meant to show how Kubewarden supports Gatekeeper policies that make use of context aware data (also called "replicating data" by Gatekeeper).