Start new private project by forking public repository on #GitHub

Let’s assume you found some very interesting public repository on a GitHub that has nice features fitting perfectly into your ideas for the new software as a service project (SaaS). Let’s also assume that you want to make some additional features that you want to keep private, so you can differentiate your SaaS from the others on the market, but you want to keep possibility to sync with original public repository, so you can have the latest development merged into your code and you can contribute some bug fixes and/or features back to public repository.

Assumptions stated above describe viable business model involving open source software as a basis, but I am not going into direction of discussing business case in this post, I want to describe how to do this technically if you are developer using GitHub as a code repository hosting service.

Here is the step by step workflow described:

Create a new repo (let’s call it private-repo) via the Github UI. Then duplicate public repo into your private-repo:

git clone --bare https://github.com/exampleuser/public-repo.git
cd public-repo.git
git push --mirror https://github.com/yourname/private-repo.git
cd ..
rm -rf public-repo.git

Clone the private repo so you can work on it:

git clone https://github.com/yourname/private-repo.git
cd private-repo
make some changes
git commit
git push origin master

To pull new hotness from the public repo:

cd private-repo
git remote add public https://github.com/exampleuser/public-repo.git
git pull public master # Creates a merge commit
git push origin master

Your private repo now has the latest code from the public repo plus your changes.

Finally, to create a pull request private repo -> public repo:

The only way to create a pull request is to have push access to the public repo. This is because you need to push to a branch there (here’s why).

git clone https://github.com/exampleuser/public-repo.git
cd public-repo
git remote add private_repo_yourname https://github.com/yourname/private-repo.git
git checkout -b pull_request_yourname
git pull private_repo_yourname master
git push origin pull_request_yourname

Now simply create a pull request via the Github UI for public-repo, as described here. Once project owners reviewed your pull request, they can merge it. Of course the whole process can be repeated (just leave out the steps where you add remotes).

NOTE: This post is based on Stackowerflow answer that could be seen here.