This is an interesting idea. It might be useful to have a high level architecture diagram to illustrate what is happening between the containers.

A couple issues:

1. Using localhost seems like a bad idea (I have the expectation that traffic is local to the instance if using localhost). 2. Managing more then a couple instances of this will be unmaintainable if done manually. There will need to be some controller logic happening.

Maybe I am missing something, but why not add a second dedicated virtual ethernet adapter where all your containers can talk (works across containers and across servers)? This is traditionally how you would handle something like this. We have dedicated nonroutable reserved address space configured to handle all this internal datacenter traffic.