This is a Docker image to build Positron in continuous integration via the TaskCluster continuous integration service, using TaskCluster's GitHub integration. It's an automated build available via a Docker Hub listing and
docker pull mykmelez/docker-build-positron.
It starts with Ubuntu 16.04 (Xenial), adds build prerequisites (as determined by Mozilla's bootstrap.py script), and includes taskcluster-vcs (which uses a cache of gecko-dev to reduce the load on GitHub when fetching changes).
The Positron repo triggers TaskCluster builds via .taskcluster.yml. TaskCluster is only available to repositories in the "mozilla" organization on GitHub. But if you have Docker installed locally, then you can use this image to build Positron (and other Mozilla apps with similar prerequisites) locally via something like:
docker pull mykmelez/docker-build-positron docker run -it mykmelez/docker-build-positron /bin/bash git clone --recursive https://github.com/mozilla/positron cd positron ./mach build