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The article demonstrates how to proxy to an external domain or a different app in ingress-nginx using a service of type ExternalName and the following annotations:

• https://kubernetes.github.io/ingress-nginx/user-guide/nginx-configuration/annotations/#rewrite
• https://kubernetes.github.io/ingress-nginx/user-guide/nginx-configuration/annotations/#custom-nginx-upstream-vhost

and optionally:

• nginx.ingress.kubernetes.io/backend-protocol
• https://kubernetes.github.io/ingress-nginx/user-guide/nginx-configuration/annotations/#server-snippet

Assume you have an app running at existing.com. And you’d like to publish one of the pages in that website as a different website. Let’s say the page is at existing.com/separate-page. Now you want to publish that page as a completely different website at new.com. First you need to create a Service resource of type ExternalName as following:

kind: Service
metadata:
  name: myservice
spec:
  externalName: plus-website.shopifycloud.com
  type: ExternalName

Then edit the Ingress resource for the same app and add the following annotations:

ingress.kubernetes.io/rewrite-target: "/separate-page"
ingress.kubernetes.io/upstream-vhost: "existing.com"

So your Ingress should look something like

kind: Ingress
metadata:
  annotations:
    nginx.ingress.kubernetes.io/rewrite-target: "/commerceplus"
    nginx.ingress.kubernetes.io/upstream-vhost: "existing.com"
  name: google-ingress
spec:
  rules:
  - host: new.com
    http:
      paths:
      - backend:
          serviceName: myservice
          servicePort: 80
        path: /

If you want to proxy over HTTPS then in the Ingress definition above you should set servicePort to 443 (or whatever the upstream listening for HTTPS requests on), nginx.ingress.kubernetes.io/backend-protocol to https and also include the following configuratoin

nginx.ingress.kubernetes.io/server-snippet: |
    proxy_ssl_name existing.com;
    proxy_ssl_server_name on;

if the upstream requires SNI.

Now whenever you access new.com Nginx will serve content from existing.com/separate-page.