Whether you're trying to give back to the open source community or collaborating on your own projects, knowing how to properly fork and generate pull requests is essential. Unfortunately, it's quite easy to make mistakes or not know what you should do when you're initially learning the process. I know that I certainly had considerable initial trouble with it, and I found a lot of the information on GitHub and around the internet to be rather piecemeal and incomplete - part of the process described here, another there, common hangups in a different place, and so on.
In an attempt to coallate this information for myself and others, this short tutorial is what I've found to be fairly standard procedure for creating a fork, doing your work, issuing a pull request, and merging that pull request back into the original project.
Steps (details below):
- Create issue if it doesn't exist
- Pull the latest
upstream/develop
into your fork - Create feature branch in your fork
- Code it up
- Commit the changes (can put multiple commits since you'll be basing the PR off the branch)
- Push the changes to
origin/develop
(your fork) - Create PR on Code4Romania repo basing
develop
<-your fork/your feature branch
- Enjoy success
Detailed instructions below.
Just head over to the GitHub page and click the "Fork" button. It's just that simple. Once you've done that, you can use your favorite git client to clone your repo or just head straight to the command line:
# Clone your fork to your local machine
git clone [email protected]:USERNAME/FORKED-PROJECT.git
While this isn't an absolutely necessary step, if you plan on doing anything more than just a tiny quick fix, you'll want to make sure you keep your fork up to date by tracking the original "upstream" repo that you forked. To do this, you'll need to add a remote:
# Add 'upstream' repo to list of remotes
git remote add upstream https://github.com/code4romania/monitorizare-vot-ios.git
# Verify the new remote named 'upstream'
git remote -v
Whenever you want to update your fork with the latest upstream changes, you'll need to first fetch the upstream repo's branches and latest commits to bring them into your repository:
# Fetch from upstream remote
git fetch upstream
# View all branches, including those from upstream
git branch -va
From this point onward, it's important to know that we use the develop
branch for work and we only merge in master
final releases. You can disregard the master
branch completely for the purpose of contributing to the project. So checkout the develop
branch and merge the upstream develop
branch.
# Checkout your master branch and merge upstream
git checkout develop
git merge upstream/develop
If there are no unique commits on the local branch, git will simply perform a fast-forward. However, if you have been making changes on develop (in the vast majority of cases you probably shouldn't be - see the next section, you may have to deal with conflicts. When doing so, be careful to respect the changes made upstream.
Now, your local develop branch is up-to-date with everything modified upstream.
Whenever you begin work on a new feature or bugfix, it's important that you create a new branch. Not only is it proper git workflow, but it also keeps your changes organized and separated from the master branch so that you can easily submit and manage multiple pull requests for every task you complete.
To create a new branch and start working on it:
# Checkout the master branch - you want your new branch to come from master
git checkout develop
# Create a new branch named newfeature (give your branch its own simple informative name)
git branch newfeature
# Switch to your new branch
git checkout newfeature
Now, go to town hacking away and making whatever changes you want to.
IMPORTANT: Prior to submitting your pull request, you might want to do a few things to clean up your branch and make it as simple as possible for the original repo's maintainer to test, accept, and merge your work.
If any commits have been made to the upstream master branch, you should rebase your development branch so that merging it will be a simple fast-forward that won't require any conflict resolution work.
# Fetch upstream master and merge with your repo's master branch
git fetch upstream
git checkout develop
git merge upstream/develop
# If there were any new commits, rebase your development branch
git checkout newfeature
git rebase develop
Optionally it may be desirable to squash some of your smaller commits down into a small number of larger more cohesive commits. You can do this with an interactive rebase:
# Rebase all commits on your development branch
git checkout
git rebase -i master
This will open up a text editor where you can specify which commits to squash.
Fetch from upstream/develop
(the main repository's develop), commit and push to origin/develop
(your fork's develop), then PR into code4romania/develop
<- <your_username>/newfeature
.
Always fetch/merge upstream/develop
into origin/newfeature
before submitting the PR. This ensures that the reviewer will be able to merge your PR if approved.
Also, keep an eye on any changes the reviewer might ask and don't delay their integration very much, otherwise your PR will become stale and it won't be merged anymore if it's too old and obsolete.
Once you've committed and pushed all of your changes to GitHub, go to the page for your fork on GitHub, select your development branch, and click the pull request button. If you need to make any adjustments to your pull request, just push the updates to GitHub. Your pull request will automatically track the changes on your development branch and update.
Make sure you're creating the PR so that your feature
branch will be merged into the upstream's develop
branch. Again, do not base it on master, but rather the develop
branch.
Take note that unlike the previous sections which were written from the perspective of someone that created a fork and generated a pull request, this section is written from the perspective of the original repository owner who is handling an incoming pull request. Thus, where the "forker" was referring to the original repository as upstream
, we're now looking at it as the owner of that original repository and the standard origin
remote.
Open up the .git/config
file and add a new line under [remote "origin"]
:
fetch = +refs/pull/*/head:refs/pull/origin/*
Now you can fetch and checkout any pull request so that you can test them:
# Fetch all pull request branches
git fetch origin
# Checkout out a given pull request branch based on its number
git checkout -b 999 pull/origin/999
Keep in mind that these branches will be read only and you won't be able to push any changes.
In cases where the merge would be a simple fast-forward, you can automatically do the merge by just clicking the button on the pull request page on GitHub.
To do the merge manually, you'll need to checkout the target branch in the source repo, pull directly from the fork, and then merge and push.
# Checkout the branch you're merging to in the target repo
git checkout master
# Pull the development branch from the fork repo where the pull request development was done.
git pull https://github.com/forkuser/forkedrepo.git newfeature
# Merge the development branch
git merge newfeature
# Push master with the new feature merged into it
git push origin master
Now that you're done with the development branch, you're free to delete it.
git branch -d newfeature
Copyright
Copyright 2017, Chase Pettit
MIT License, http://www.opensource.org/licenses/mit-license.php
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