So in the places i've been, someone has usually managed to deploy ingress-nginx in Kubernetes. And usually that means an "external" and an "internal" deployment.
Most people only seem to figure out the external part: Setup DNS to point to your cloud load balancer, configure Ingress objects to match those external DNS names.
But what about the internal one? You could:
Rewrite an external name or serve up a new internal domain with the resolved address being that of internal ingress'es Service virtual IP. Demonstrated by this coredns blogpost.
Or... you could set http_proxy in your clients to point at the internal ingress.
There is a bit of difference in the requests,
but it shouldn't really matter for routing.
Note that this only really works with plain HTTP
as HTTPS is going to get a CONNECT request instead to tunnel through to the target.
Plain request:
GET /foo HTTP/1.1
Host: example.com
User-Agent: curl/8.1.2
Accept: */*
Proxy request
GET http://example.com/foo HTTP/1.1
Host: example.com
User-Agent: curl/8.1.2
Accept: */*
Proxy-Connection: Keep-Alive