Put a git repo as a subfolder in another git repo

git-repo-as-subfolder.md

This is a short guide on how to put all files from a Git repository into a folder in another Git repository.

1. Go the subrepo (REPO1), switch to the branch you want to merge, and make a new temporary branch.

   cd REPO1
   git checkout BRANCH_TO_MERGE
   git checkout -b TEMP_BRANCH

2. Move the files you want to relocate into a subdirectory within the same repository.

   mkdir TARGET_SUBFOLDER
   git mv * TARGET_SUBFOLDER
   git commit -m "Move files to the target subfolder"

   The file structure has to represent what the target repo should look like after the merge (only in terms of the merged subrepo).

3. Create a bundle of the branch that contains the moved files.

   git bundle create ../repo1_bundle TEMP_BRANCH

4. In your target repo (REPO2), fetch the bundle and create a new branch from it.

   cd ../REPO2
   git fetch ../repo1_bundle TEMP_BRANCH:NEW_BRANCH

5. Merge the changes from REPO1 into REPO2.

   git checkout master
   git merge NEW_BRANCH --allow-unrelated-histories

6. Clean up by removing the temporary branch and bundle.

   # Clean up REPO2
   git branch -d NEW_BRANCH
   rm ../repo1_bundle
   
   # Clean up REPO1
   cd ../REPO1
   git checkout BRANCH_TO_MERGE
   git branch -d TEMP_BRANCH