[atbell]

I'm extremely surprised that Packer (http://www.packer.io) hasn't received more attention in the Docker arena. Its Docker builder, coupled with any of its provisioners, makes it a pretty attractive alternative to the simplistic layout and limitations of Dockerfiles.

[mtalantikite]

Packer currently doesn't snapshot the build at each step, so you don't get a history that you can checkout or push from. It's a feature that's on the way, but it's a pretty big one that some teams need.

We use packer for a lot of other things though and it's great.