Create a new Git repository from current HEAD, set it as a remote of the original, and mirror future changes to both repositories?

Question

The current repository has commits

  A -> B -> C
            ^
            |
         HEAD

I want to create a new repository whose master branch begins at commit C (HEAD) of the current repository.

  C
  ^
  |
HEAD

Additionally, if a new commit D is added to the current repository:

  A -> B -> C -> D
                 ^
                 |
                HEAD

The new repository will become:

  C -> D
       ^
       |
      HEAD

On the next push/mirror.

Due to learning to develop software while I committed changes to the project, the repository has gone in size due to large files being added and removed through it's long history (500 commits).

Can this workflow be easily achieved in git? (Using both GitHub and GitLab)

Answer 1

You can easily create a new repo from an existing one, at least locally: just git clone <src repo> [dest dir] (possibly using --depth or similar to save on size, though that comes with caveats, see the manual for details). Making that new repository automatically follow the original's history isn't going to be easy though. The new repo will have its origin setup to point at the original, but updating will require a pull/fetch+merge/whatever as usual. You may be able to set up some post-commit hook in the old repo to automate the cd <new repo> ; git pull ; cd $OLDPWD bit, I'm not well-versed in how git's hooks work. Alternately, you could set up the new repo as a remote in the old one and push to it, though I'm not sure how that'd affect the new repo's working tree (i.e., what's checked out). And making any of this work with a remote provider like GitHub would be an entirely different can of worms.

If you want to try cleaning up your history, you may want to look into rebase and possibly cherry-pick.