Use versioned openedx-translations in deployments

[timmc-edx]

Currently, deployments of edxapp pull the latest from https://github.com/openedx/openedx-translations at build time, and this version is not tracked or managed. This means that we don't have a way to work around a bad translation other than A) rolling back to a sufficiently old deploy, which may not be usable or B) fixing forward, which takes over an hour.

A minimal mitigation would be to include https://github.com/openedx/openedx-translations as a material in the GoCD pipeline and set the REVISION environment variable to match the material when pulling translations.

Notes

• We pull translations during the edxapp build in the configuration repo's playbooks/roles/edxapp/tasks/deploy.yml in task Pull translations using Atlas, which calls make pull_translations. This in turns calls atlas pull which accepts an environment variable ATLAS_OPTIONS.
• Atlas accepts --repository and --revision options.
  • Problem: "Git revision to pull from. Currently only branches and tags are supported." There's an open issue for that. Maybe we can make a PR.
• Under GoCD, we can probably attach a material for openedx-translations and then pass its revision value to the call.

[jristau1984]

Refinement questions...

• Is this worth prioritizing before the containerization workstream is complete?
• Is this something that should be done by Arch-BOM, or a different team (e.g. FedX)?

[timmc-edx]

I took a look at what this would involve and added notes to the ticket. I think it's worth pursuing in GoCD. Should be pretty straightforward.

[timmc-edx]

...I ended up opening a PR for the needed atlas changes: openedx/openedx-atlas#61 Let's see if that gets accepted. Beyond that it should be pretty straightforward.