I tried to leave a comment on the author's blog, but it crashed. Instead I will leave one here. We have a number of docker images that we use at DevTable to provide environments for user-hosted software (think: development servers). There was no official way to host them privately, so we built it! Quay.io (
https://quay.io) lets you store your images privately, as well as having a rich access management system to allow you to delegate read, management, and administration privileges.