[shriphani]

The bit about turning a dockerfile into a rootfs. A docker image is just a tarball of tarballs. We do something like this:

- you can dump the image using `docker save <name>`. - you can then get a list of the tarballs in this image by extracting this tarball and reading the file `manifest.json`; `Config` -> `Layers` will give you a list of tarballs (see undocker for how to do this: https://github.com/larsks/undocker) - Untar these in a directory and use linux tools to convert this dir to a rootfs.