[regularfry]

If I do an `apt-get install` of the same packages in different containers, with anything different at all before it in the Dockerfiles, there's no way to share a common layer that includes the package contents between those images.

You could volume mount /usr and chunks of /var to help, but I'm not sure that would be sane.

[radicalbyte]

There are storage systems which do this, de-dupe on disk level.