Git Filter Repo — Splitting a Subfolder Into A New Repository

Welcome to 2021! This is my first blog post of the new year and I’m excited to get back to writing. Let’s dive right in.

The Task: Pulling a Frontend Repository From a Combined Frontend/Backend Project

I’ve worked on a project for some time that has one GitHub repository containing both the frontend and backend applications.

PROJECT/ .git/ BACKEND/ FRONTEND/

Recently, it finally came time to split these applications apart:

BACKEND/ .git/ APP/ FRONTEND/ .git/ APP/

Preserving Git History

One obviously problem with creating a new repository from a subfolder is preserving git history. Losing years of git history or losing current branches in development would have been a non-starter.

This post shares the exact steps I used to create a new frontend repository from the project while preserving git history. The key here was a tool called git filter-repo. The git CLI itself advised me to use git filter repo instead of the native git filter-branch command.

Instructions

1. Install git-filter-repo

brew install git-filter-repo

2. Change directories to the location where you would like to create the new frontend repository

cd ~

3. Clone down the original PROJECT repository and change directories

git clone git@github.com:[PROJECT]
cd PROJECT

4. Run git filter-repo

git filter-repo --subdirectory-filter FRONTEND/ --tag-rename '':'frontend'

5. Create FRONTEND repository in GitHub

6. Add the remote branch

cd FRONTEND
git remote add origin git@github.com:[FRONTEND]
git branch -M main
git push -u origin main

7. Push all git branches to the remote

git push remote --all

And that’s it! I hope you found this post helpful and thank you for reading.

Resources

• git filter-repo GitHub
• git filter-repo man page
• Pushing all local branches to a remote
• Moving Files and Directories to a New Repository in Git
• Detach (move) subdirectory into separate Git repository
• Splitting sub-folder(s) out into a new Git repository

Originally published at https://www.edezekiel.com.