Disallow empty Ingress host

 1apiVersion: kyverno.io/v1
 2kind: ClusterPolicy
 3metadata:
 4  name: disallow-empty-ingress-host
 5  annotations:
 6    policies.kyverno.io/title: Disallow empty Ingress host
 7    policies.kyverno.io/category: Best Practices
 8    policies.kyverno.io/severity: medium
 9    policies.kyverno.io/subject: Ingress
10    policies.kyverno.io/description: >-
11      An ingress resource needs to define an actual host name
12      in order to be valid. This policy ensures that there is a
13      hostname for each rule defined.      
14spec:
15  validationFailureAction: enforce
16  background: false
17  rules:
18    - name: disallow-empty-ingress-host
19      match:
20        resources:
21          kinds:
22            - Ingress
23      validate:
24        message: "The Ingress host name must be defined, not empty."
25        deny:
26          conditions:
27            - key: "{{ request.object.spec.rules[].host || `[]` | length(@) }}"
28              operator: NotEquals
29              value: "{{ request.object.spec.rules[].http || `[]` | length(@) }}"