Note: This project is unmaintained and possibly outdated. You can skim through it to get some ideas on how to setup your images, but the Dockerfiles are not guaranteed to work without modification.
An official Docker image currently is available for Bitbucket Server. Find the setup and Dockerfile here: https://bitbucket.org/atlassian/docker-atlassian-bitbucket-server
This experimental project was originally created to record the experiments detailed in article "Docker all the things at Atlassian: automation and wiring" which you can still read at:
http://blogs.atlassian.com/2013/11/docker-all-the-things-at-atlassian-automation-and-wiring/