[nyrikki]

While not as small it is trivial to make an up-to-date debian base image (or Fedora/Arch) any time you want. If you care about security you probably don't want to use random unverified images anyway.

  $ sudo debootstrap stretch mydebian http://mirrors.kernel.org/debian/
  $ cd mydebian
  $ sudo tar -c . | docker import - mydebian

Plus you can add files to the system before taring etc...

If you have significant work to do on an image a Dockerfile can often be far more complex than this method.