So i am trying to use ExternalName service to allow cross namespace application to use the ingress (Application in namespace1 using ingress in namespace2 via ExternalName service type). Here is my original service

metadata:
  annotations:
    cloud.google.com/neg: '{"ingress":true}'
  labels:
    app.kubernetes.io/component: app1
    app.kubernetes.io/instance: app1
  name: app1-svc
  namespace: app1-namespace
spec:
  internalTrafficPolicy: Cluster
  ports:
  - name: http
    port: 8080
    protocol: TCP
    targetPort: 8080
  selector:
    app.kubernetes.io/component: app1
    app.kubernetes.io/instance: app1
  sessionAffinity: None
  type: ClusterIP

The setup in namespace2 include an ingress and a service (Type: ExternalName) as below

apiVersion: v1
kind: Service
metadata:
  name: external-svc-for-app1-svc
  namespace: app2-namespace
  annotations:
    cloud.google.com/neg: '{"ingress": true}'
spec:
  type: ExternalName
  externalName: app1-svc.app1-namespace.svc.cluster.local
  ports:
  - name: http
    port: 80
    protocol: TCP
    targetPort: 80

--------------------------------------------------

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: ingress-ns2
  namespace: app2-namespace
  annotations:
    kubernetes.io/ingress.allow-http: "false"
    cert-manager.io/cluster-issuer: letsencrypt
    kubernetes.io/ingress.class: gce-internal
    kubernetes.io/ingress.regional-static-ip-name: <ip-address>
spec:
  tls:
    - secretName: ingress-ns2-tls
      hosts:
        - <app1.example.com>
  rules:
    - host: <app1.example.com>
      http:
        paths:
          - path: /*
            pathType: ImplementationSpecific
            backend:
              service:
                name: external-svc-for-app1-svc
                port:
                  number: 80

Backend service got created for this external service and so as NEGs, the issue is Network endpoints are not being configured for the external service. I have to manually provide the network endpoints to make it work.

I have tried using nginx ingress as well as gce ingress, it did not work.
Theoretically it should configure the endpoint in NEGs as the External svc points to the actual service via internal DNS <service>.<name-space>.svc.cluster.local and i am able to curl this from any pod in app2-namespace and the traffic routes to the orignal service as well as i mentioned it works when i manually provide the network endpoint for app1.
I looked into some posts but most of them say the traffic routing is not working, it works now with ExternalName service, the only issue is Network endpoint is not being configured.