nginx-ingress-external-service.yaml

kind: Service
apiVersion: v1
metadata:
  name: private
spec:
  type: ExternalName
  externalName: private.example.corp
  ports:
  - port: 443
    protocol: TCP
    targetPort: 443
---
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: published-private
  annotations:
    nginx.ingress.kubernetes.io/backend-protocol: "HTTPS"
    nginx.ingress.kubernetes.io/upstream-vhost: "private.example.corp"
spec:
  ingressClassName: nginx
  rules:
  - host: published-private.ext.example.com
    http:
      paths:
      - backend:
          service:
            name: private
            port:
              number: 443
        path: /
        pathType: ImplementationSpecific
  tls:
  - hosts:
    - published-private.ext.example.com