Release script for setting the GitLab image versions.
Action item from chart versioning proposal: https://gitlab.com/charts/gitlab/issues/473
Currently blocked waiting on https://gitlab.com/charts/gitlab/issues/479 and https://gitlab.com/charts/gitlab/issues/481
This script should accept a new Chart version or an existing GitLab Rails version, and use that version to check the rails repository to determine the appropriate Gitaly and Gitlab Shell version to use.
It should use it's version information to find the appropriate stable branch (using branch naming defined in https://gitlab.com/charts/gitlab/issues/474)
If given a rails version instead of a chart version it should check the latest stable branch to see if it is the ideal branch, or to determine if it needs to create a new stable branch. (For the first iteration we will ignore dealing with rails versions that should go in older branches, meaning the whole script is a no-op for now, if we see that the latest stable branch already contains a newer rails version.)
Once it has found the branch, it should update the image versions, and call the bump chart version script from here: https://gitlab.com/charts/gitlab/issues/481, and commit.
If the script was passed a chart version, OR a rails version that was not an RC, it should generate the changelog, and tag the release.
Ideally this script should re-use some of the code from our other release-tools code, but as a seperate rake task. As part of the initial work on this issue, the dev should evaluate creating this script as a task within the release tools repo: https://gitlab.com/gitlab-org/release-tools