https://docs.docker.com/articles/dockerfile_best-practices/
http://crosbymichael.com/dockerfile-best-practices-take-2.html
https://journal.paul.querna.org/articles/2013/10/15/docker-ubuntu-on-rackspace/
https://github.com/phusion/baseimage-docker/blob/master/image/prepare.sh
https://github.com/docker/docker/blob/master/contrib/mkimage/debootstrap
Standard mkinstall below includes initrd fix, dpkg apt speedup and preventing service starting by policy-rc.d and/or upstart
Probably don't need to worry about this:
Replace the 'ischroot' tool to make it always return true. Prevent initscripts updates from breaking /dev/shm. https://journal.paul.querna.org/articles/2013/10/15/docker-ubuntu-on-rackspace/ https://bugs.launchpad.net/launchpad/+bug/974584
dpkg-divert --local --rename --add /usr/bin/ischroot ln -sf /bin/true /usr/bin/ischroot