Earlier this year I spent some time modernizing and improving Balrog's toolchain. One of my goals in doing so was to switch from Travis CI to Taskcluster both to give us more flexibility in our CI configuration, as well as help dogfood Taskcluster-Github. One of the most challenging aspects of this was how to build and push our Docker image, and I'm hoping this post will make it easier for other folks who want to do the same in the future. The Task Definition Let's start by breaking down Task...| Ben Hearsum