This answer might be a bit late, but what you need is an automatic reverse proxy. I have used two solutions for that:

• jwilder/nginx-proxy
• Traefik

With time, my preference is to use Traefik. Mostly because it is well documented and maintained, and comes with more features (load balancing with different strategies and priorities, healthchecks, circuit breakers, automatic SSL certificates with ACME/Let’s Encrypt, …).

Using jwilder/nginx-proxy

When running a Docker container Jason Wilder’s nginx-proxy Docker image, you get a nginx server set up as a reverse proxy for your other containers with no config to maintain.

Just run your other containers with the VIRTUAL_HOST environment variable and nginx-proxy will discover their ip:port and update the nginx config for you.

Let say your DNS is set up so that *.test.local maps to the IP address of your Docker host, then just start the following containers to get a quick demo running:

# start the reverse proxy
docker run -d -p 80:80 -v /var/run/docker.sock:/tmp/docker.sock jwilder/nginx-proxy

# start a first container for http://tutum.test.local
docker run -d -e "VIRTUAL_HOST=tutum.test.local" tutum/hello-world

# start a second container for http://deis.test.local
docker run -d -e "VIRTUAL_HOST=deis.test.local" deis/helloworld

Using Traefik

When running a Traefik container, you get a reverse proxy server set up which will reconfigure its forwarding rules given docker labels found on your containers.

Let say your DNS is set up so that *.test.local maps to the IP address of your Docker host, then just start the following containers to get a quick demo running:

# start the reverse proxy
docker run --rm -it -p 80:80 -v /var/run/docker.sock:/var/run/docker.sock traefik:1.7 --docker

# start a first container for http://tutum.test.local
docker run -d -l "traefik.frontend.rule=Host:tutum.test.local" tutum/hello-world

# start a second container for http://deis.test.local
docker run -d -l "traefik.frontend.rule=Host:deis.test.local" deis/helloworld