Routing subdomains to services

As I understand, kubernetes will no longer require a proxy as DNS is built right in. Does a strategy exist in Rancher 2.0 which allows telling the system to which service to route an incoming request?

I would like to be able to specify a subdomain which a container wants to receive (e.g. in Dockerfile) which then automatically makes the routing entries when the service is started and removes these when the service is stopped. How will this work with Rancher 2.0?

More info:

We currently use Docker Cloud which will soon be shut down. I believe Docker Cloud uses HAProxy in a similar way as older Rancher versions where the service links into the proxy upon startup and tells it the routing for a given subdomain.

For example, on Docker Cloud we can tell HAProxy in the Dockerfile of the container associated with a Service, requests of which subdomain it wants to receive.

This is basically the idea of the ingress controller:

There are also third-party things that watch for certain labels/annotations on pods and update the config of balancer/router container.