Do you have an example how that would work? I unsuccessfully spent quite a while trying to get a docker container running rails to talk to a docker container running postgre. And I wanted to postgre container to persist to the host's disk so I could save state between runs. Maybe that wasn't the best way to do it though?

DB data can be stored in volume and persisted.

There are a lot of dockerfile / compose examples on github.

* https://github.com/docker/awesome-compose * https://github.com/jessfraz/dockerfiles