[curun1r]

This is a pretty easy solve...haproxy + consul + consul-template allows you to spin up a new container, register it with consul and have the consul-template watcher regenerate the haproxy config to route to the new port.

It's a little overkill if you're running it on a single machine, but in a real production environment, it's a pretty lightweight solution.

[otterley]

Easy in theory, but in practice, you have to configure and monitor it all. Adding components and orchestration logic is not cost-free.

[coffeemaker]

Well it's not so hard. If there is good document steps for it. It's really abut getting consul working right.