* Fix bug on creating the testing container for PRs and create a function to
run docker image prune -f that will get run when the script exits cleanly or
uncleanly. This prevent junk containers from building up over time.
* Add in some labels and keys. Add in building containers on master branch.
* Let's also build on main branch for when we eventually move away from master.
* Let's use a previous builder image as a cache as it might speed things up.
* WIP multi-stage container build.
* Move to a multistage build process in the Containerfile.
* Enable testing container
* Finalize the multistage build script and Containerfile. Ooof!
I got blocked for a bit with this bugger:
Step 27/32 : COPY --from=builder --chown=${APP_USER}:${APP_USER} ${APP_HOME} ${APP_HOME}
failed to copy files: failed to copy directory: Error processing tar file(exit status 1): Container ID 100999 cannot be mapped to a host ID
but https://github.com/phusion/passenger-docker/issues/235#issuecomment-636318827
was a good shove in the right direction!
* Fix bugs on container build script.
* Adjust compose files to use multistage builds.
* Add in Buildkite pipeline for building containers.
* Update CODEOWNERS to claim ownership over things that Systems Eng cares about
