Your best bet is really to build your base image using debootstrap or similar. The 'official' images are often a joke. For the longest time, the maintainer of the 'official' Ubuntu image had no clear association with either Docker Inc or Canonical.

edit: To clarify, the images themselves are quality, and do get generated from Canonical's rootfs tarball, but the trust path for a huge chunk of binary data now hinges on a single individual, rather than a corporate entity.