ariejan de vroom

Contributing to Open-Source with Github

9 November 2011

You want to contribute to an open-source project, but are scared away by all the git-complexity involved? This small guide will help you out.

Octocat

Step 1 - Fork, fork, fork

First create a fork of the original project. You can do this easily by clicking the “Fork” button on the top of the Github project page. This will give you your own copy (fork) of the entire repository.

Then, check out your fork:

git clone git@github.com:ariejan/repo-name.git

Step 2 - Contribute

Before you start writing code there are a few tasks you need to perform:

Step 3 - Sharing your contribution

With your contribution done, don’t merge it back into master. master is your way of receiving changes from the original (upstream) repo (see step 4).

First push your branch to Github, so you can share it with others.

git push origin fix_for_this_or_that

You should now see this branch in your Github project page. You’ll also notice there’s a “Pull Request” button at the top. Click it if you want the project maintainer to pull your fix_for_this_or_that branch into the main project.

Step 4 - Keeping up-to-date

Over time the master of your fork will start lagging behind. Because you did not merge any of your code changes into the master of your fork, you can update it easily.

Before you can pull in changes you must add a git remote for it. You can use the Git Read-only URL for this.

git remote add upstream https://github.com/some_one/some-repo.git

Now, for raking in the changes;

git checkout master
git fetch upstream
git merge upstream/master

Step 4.5 - Keeping your feature branch up-to-date

If you pulled in changes from upstream and did not yet share your feature branch, you can rebase your feature branch. This makes sure you have the latest code from master. This also makes merging your pull request easier.

Do not rebase if you already pushed your branch to Github. Read why.

git checkout fix_for_this_or_that
git rebase master

If any conflict arise, fix them. And continue your rebase:

git add conflicting_file
git rebase --continue

You may also abort the rebase:

git rebase --abort

Big picture

This small guide will help you to fork repositories on Github and use them to contribute code. By using the approach you lighten the task of the project maintainer who can easily checkout your specific changes and decide to include them into the main project or not.