Add SUBTREE support to Gitlab

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Release notes

There are many cross repo version control strategies that are used in development that include the use of GIT utilities like submodules. Indeed, Gitlab actively supports submodules via its gitmodules interface. However, GIT Subtrees have their added advantages and use cases as well. I am proposing that support for Git Subtrees be added to Gitlab either as an additional component of gitmodules , as its own bespoke Gitlab interface or at the minimum a visual alert on the presence of a Git Subtree in Merge Request UI/UX sessions.

Problem to solve

As of the creation of this proposal, when development teams attempt to incorporate traditional Git subtrees within a Gitlab repo which makes use of CI/CD, the process can be a very cumbersome one:

• The Gitlab Repo's .git does not correctly distinguish externally derived subtrees as subtrees; Git Submodules are treated far better.
  • MR/PR sessions are littered with extra subtree content that clutters actionable code changes related to the local repo itself, as the .git playhead picks up all changes by default, even externally sourced ones.
  • As a result, changes that are exclusive to the subtree'd repo appear to be local changes to the repo within the subtree exists and are tracked by the git HEAD as such.
• Multiple git boilerplate commands must be used to update , create and rebase a typical subtree while much of the heavy lifting complexity of submodules is quietly simplified for the user via the gitmodules interface.

Intended users

All Gitlab users who:

• Make use of Git Subtrees rather than or in addition to Git Submodules via gitmodules
• Would like to ensure their users/teams can have an easy at-a-glance delineation of where code is sourced from when no changes are made to a subtrees content in a local repo.

User experience goal

At minimum, A user who has used a Git Subtree in their Gitlab repo should have

• Their .git not hard track changes of a subtree unless a change was made to the contents of the subtree in the local repo it's been pulled into
  • I acknowledge this may be difficult to do.
• At minimum, the ability to flag an added subtree (e.g. git remote add -f [my-subtree] ``git@gitlab.com``:My/remote/repo/to/add.git && git subtree add --prefix [my-subtree] ... ) for Gitlab Merge Request UI/UX de-cluttering.
  • Something like a simple bit of iconography or prompting text (like what is used to distinguish LFS files in a Gitlab Repo) would help to cite this for the code reviewer
  • Pre-folding/collapsing subtree code that was added which have NO LOCAL Changes within the local repo (e.g. auto-hide noisy code).

Available Tier

Ideally, this sort of functionality should exist at the same level of tier that the current gitmodules interface exists at.

What is the competitive advantage or differentiation for this feature?

No other Version Control System that uses GIT as its base currently does this as far as I know.

Links / references