Can we use custom resources for Mutating admission webhook

General Discussions
1

Cluster information:

Kubernetes version:
k3d version v5.3.0
k3s version v1.22.6-k3s1 (default)
Kubernetes version 1.22.6
Cloud being used: (put bare-metal if not on a public cloud) - No (Local Installation)
Host OS: Linux

I am trying to use mutating webhook for custom resources like Istio’s VirtualService.
But my webhook is not getting triggered. i ended up putting * everywhere in webhook yaml to debug but it does not seems to work, So, i am wondering if webhooks are supported for custom resources. ???

Webhook -

apiVersion: admissionregistration.k8s.io/v1
kind: MutatingWebhookConfiguration
metadata:
  name: "mutatingwebhook.mutatingwebhook.svc"
  annotations:
    cert-manager.io/inject-ca-from: mutatingwebhook/selfsigned-crt
webhooks:
- name: "mutatingwebhook.mutatingwebhook.svc"
  namespaceSelector:
    matchLabels:
      webhook: enabled
  rules:
  - apiGroups:   ["*"]
    apiVersions: ["*"]
    operations:  ["*"]
    resources:   ["services", "virtualservices"]
  clientConfig:
    service:
      namespace: "mutatingwebhook"
      name: "mutatingwebhook"
      path: "/api/test-webhook"
  admissionReviewVersions: ["v1", "v1beta1"]

Virtual Service -

apiVersion: networking.istio.io/v1alpha3
kind: Gateway
metadata:
  name: bookinfo-gateway
spec:
  selector:
    istio: ingressgateway # use istio default controller
  servers:
  - port:
      number: 80
      name: http
      protocol: HTTP
    hosts:
    - "*"
---
apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
  name: bookinfo
  annotations:
    test.controller/group: test2
spec:
  hosts:
  - "*"
  gateways:
  - bookinfo-gateway
  http:
  - match:
    - uri:
        exact: /productpage
    - uri:
        prefix: /static
    - uri:
        exact: /login
    - uri:
        exact: /logout
    - uri:
        prefix: /api/v1/products
    route:
    - destination:
        host: productpage
        port:
          number: 9080