quaunaut: I've never used Dokku so I'm not sure if this is helpful, but I've been experimenting with using https://github.com/progrium/buildstep to build containers using buildpacks. I'm finding that it allows for fast builds and a consistent image that I can push/pull to different environments. There is a PR (https://github.com/progrium/buildstep/pull/50) for adding buildpack caching that makes the builds even faster by caching gems and assets (I happen to be using it for a rails project).