This looks like a nice write up guide, was just wondering here, how do you keep docker builds tags from clashing if they're all running on the same Docker instance?
Sadly they have to operate cooperatively. :/ I've taken great pains to prefix all of my builds with "${CI_JOB_ID}" and add a `clean` step at the end to tear down all created images. It's not perfect, but it works well enough in a trusted environment.