This image is SàT backend built without media: if you only use text frontends, you can choose to use this image as backend to save space.
You can find full use instructions on SàT wiki: http://wiki.goffi.org/wiki/Docker/en
More info on the project on the official website: http://salut-a-toi.org
If you have any issue or want to discuss about the projet, you can join us on the XMPP muc room: email@example.com
The dockerfile is available here
You can build get all the dockerfiles and script to manage them with mercurial:
hg clone http://repos.goffi.org/sat_docs
Everything is in "docker" directory.