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    Ongoing observations by End Point Dev people

    How to split Git repositories into two

    By Wojtek Ziniewicz
    August 14, 2017

    Ever wondered how to split your Git repo into two repos?

    First you need to find out what files and directories you want to move to separate repos. In the above example we’re moving dir3, dir4, and dir7 to repo A, and dir1, dir2, dir5, and dir8 to repo B.

    Steps

    What you need to do is to go through each and every commit in git history for every branch and filter out commits that modify directories that you dont care about in your new repo. The only flaw of this method is that it will leave those empty, filtered out commits in the history.

    Track all branches

    First we need to start tracking all branches locally:

    for i in $(git branch -r | grep -vE "HEAD|master" | sed 's/^[ ]\+//');
      do git checkout --track $i
    done
    

    Then copy your original repo to two separate dirs: repo_a and repo_b.

    cp -a source_repo repo_a
    cp -a source_repo repo_b
    

    Filter the history

    Following command will delete all dirs that exclusively belong to repo B, thus we create repo A. Filtering is not limited to directories. You can provide relative paths to files, dirs etc.

    cd repo_a
    git filter-branch --index-filter 'git rm --cached -r dir8 dir2 || true' -- --all
    
    cd repo_b
    git filter-branch --index-filter 'git rm --cached -r dir3 dir4 dir7 || true' -- --all
    

    Note that the || true prevents git from failing to filter our dirs mentioned in the rm clause in early stages of the git history where the dirs did not yet exist.

    Look at the list of branches once again (in both repos):

    git branch -l
    

    Set new origins and push

    In every repo, we need to remove the old origin and set up new origin. After it’s done, we’re ready to push.

    Remove old origin:

    git remote rm origin
    

    Add new origin:

    git remote add origin git@github.com:YourOrg/repo_a.git
    

    Push all tracked branches:

    git push origin --all
    

    That’s it!

    git


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