A Primer On Contributing To Projects With Git

posted on 2017-03-08 at 14:10 EST

There isn't any shortage of tutorials on this subject, but I haven't seen any that attempt to guide a person that has zero experience with any of it. So, the goal of this article is to give a fresh "newbie" all of the information they need to collaborate on projects that use the Git SCM. This will not be a complete, or even a full introductory, guide to git; you should read other tutorials, and the reference docs for that.

Setup

We will focus on using the command line interface. Thus, to start, we need to setup the environment.

Windows

I am not a Windows person. My day job is a Linux administrator and my full-time desktop environment is Appple macOS. Given that, the easiest environment I have found for Windows is to:

  1. Install msysgit
  2. Install ConEmu
  3. Configure the default "task" for ConEmu to the one that uses the Bash shell provided by msysgit

Linux

This will vary based on the distribution you use. The short of it is that you need to install their package that provides git; typically, the name of the package is simply "git".

If you are using Void Linux (my preference), then I recommend installing both the "git" and "git-perl" packages.

macOS

I prefer using the "git" package from MacPorts. But the easiest way to get started is to simply open a Terminal.app session and execute git:

$ git
  $ # you will be prompted to install the necessary components
  

Speaking of Terminal.app, I recommend switching to iTerm2. It's just better.

Config

With git installed, you should now configure it to know some details about you. These details will be used to identify you on the changes that you make within a project:

$ git config --global user.name 'FirstName Surname'
  $ git config --global user.email 'your.email@example.com'
  

Authentication

We will discuss central repositories shortly, but regardless of how the project you wish to contribute to chooses to centralize, you will need to authenticate yourself when synchronizing your contributions. You have two options:

  1. Communicate with the central repositories over HTTPS
  2. Communicate with the central repositories over SSH

In case #1, you will be prompted for your user credentials each time you work with the remote system. You can minimize this by using a "credential helper." A nice overview of getting such a helper setup is available at http://stackoverflow.com/a/5343146/7979.

As for case #2, you will need to create an SSH key pair for yourself and configure the remote system to recognize it. Given the complexity of this method, we will assume the first method is being used. If you want to learn about the SSH method, then I am sure whichever central system your project uses will have instructions that will help you out.

Collaboration

Now that we have a working git environment, we can learn about how to actually use it to collaborate on a project.

Account Setup

Whether you are working solely within an institution or you are participating in an open source project, you will be working with a central repository. There are many ways a repository can be hosted centrally, but the most common, and the ones we will assume in this article, are provided by the following services:

  1. GitHub
  2. GitLab
  3. Bitbucket

All three offer some form of on-premises solution, public hosted repositories, and private hosted repositories. Regardless of the service provider and its location, you will need an account with the service. Thus, the easiest step is the first -- create an account.

For the rest of this article we will assume you created a GitHub account at github.com.

Git And GitHub

git is a distributed source code management tool. This means that git is intended to be used locally, without a central server. But all of the sites outlined in account setup are centralized server. So we need to think of sites like GitHub as a system that many people have "local" accounts on where they store their git repositories. This allows the users to make their repositories available to other users of the GitHub system, such that those users can create their own copy of other users's repositories. In turn, this allows GitHub to provide features on top of the standard git features.

As a brief overview of the remainder of this article, the workflow created by this setup is as follows:

  1. Bob creates a git repository on his local machine.
  2. Bob copies it to his GitHub account, thus making the real respository the one hosted on the GitHub system.
  3. Alice decides she likes Bob's project and wants to help him with it, so she "forks" (copies) the repository to her own GitHub account.
  4. Alice "clones" her copy of the repository on the GitHub system to her local computer.
  5. Alice tells her local repository about Bob's "upstream" (original) repository so that she can stay up-to-date with Bob's changes.
  6. Alice creates a "branch" on her local repository, makes changes, and "pushes" those changes to her fork on the GitHub system.
  7. Alice uses the GitHub interface to tell Bob about her changes, asking if he'd like to incorprate them into his original repository.
  8. Bob decides he likes the changes, accepts them, and his repository on the the GitHub system is updated.

Fork The Project

For remainder of this article we will assume that you want to collaborate on the awesome Pino project. Our first step is to create a copy of the project in our account on GitHub. So we navigate to [https://github.com/pinojs/pino] in a web browser and click "Fork" button (currently in the upper right corner of the page). GitHub will then show a screen that the process is happening, and then load the Pino repository in your account.

Cloning

Now that Pino has been forked to your account, we will "clone" it to your local machine. Cloning, in this context, is merely copying the repository from your GitHub account to your personal computer. To accomplish this task, we use our terminal and enter:

$ cd ~/Projects # or any place you want to keep a collection of projects
  $ git clone https://github.com/your-username/pino.git
  

At this point you will have a directory: ~/Projects/pino. This directory is your local copy of the repository. This local copy is automatically tied to your copy of the repository on the GitHub system. This link between your two copies is known locally by the name "origin". Within git this is known as a "remote". To see the remotes associated with your local repository, which, at this point, is only "origin", issue the commands:

$ cd ~/Projects/pino
  $ git remote
  

For more information on remotes, read https://git-scm.com/docs/git-remote.

Before you begin working on your changes it is a good idea to connect your local repository to the original repository. Colloquially, this is known as the "upstream" remote. From within your local repository, issue the following command:

$ git remote add upstream https://github.com/pinojs/pino.git
  

Create A Feature Branch

We are now ready to begin working on some changes to the project. The key to successful collaboration is to request the minimal amount of changes as is necessary to implement your idea (or fix). You should do this on a new branch within your repository. A branch is merely a snapshot of the repository at a specific point in time. By working on a branch you lock the project to the state at which you decided you want to add changes, and it makes it easier for the upstream project owners to review your changes when you submit them.

Typically, you will want to name your branch in such a way that it indicates why the branch was created. So, let's assume we want to make some documentation corrections. Enter the following command from within your local copy of the repository:

$ git checkout -b doc-corrections
  

The above command is a shortcut for the following two commands:

$ git branch doc-corrections
  $ git checkout doc-corrections
  

Every repository has what is known as a master branch. At this point, we have started a new branch, doc-corrections from the current state of the master branch. To see the branches available:

$ git branch
  

Before moving on, let's also create the doc-corrections branch within your copy of the repository on GitHub. To do this, we will "push" our branch:

$ git push -u origin doc-corrections
  

This has done two things:

  1. It has created the doc-corrections branch in your repository on GitHub.
  2. It has configured your local copy of the repository to know that the local doc-corrections corresponds to the doc-corrections in your GitHub copy of the repository. This allows for some shortcuts when issuing certain git commands.

To learn more about branching and pushing, see:

Making Changes

Now that we are on our own branch we can make our changes. For now, let's pretend you have made some typo corrections to the README.md file. Which is to say, you have opened README.md in your text editor, adjusted the text within and saved the document. If you issue the following command:

$ git status
  

You will see that git has recognized that you made changes to the file. At this point git isn't going to do anything with those changes. Files that are tracked by a git repository have two stages: modified and scheduled to be committed. In the "modified" state git merely recognizes that a file has been changed from its initial state. In the "scheduled to be committed" state git will write the changes made to the file into its internal tracking when the git commit command is run. So, let's move our changes from the modified state to the schedule state:

$ git add README.md
  

With the changes scheduled to be committed, let's actually perform the commit:

$ git commit -m 'A short summary of the changes'
  

The above is the equivalent of sending an email with nothing more than the subject line filled in. To write a full commit message, simply issue git commit. This will open the default commit editor, probably a variant of vi. A full commit message should have the following format:

A short summary of the changes
  
  A body describing in further detail your changes.
  The summary line should not exceed 40 to 50 characters, and the body
  lines should not exceed 80 characters. Thes are not hard and fast
  rules, per se, but they widely followed guidelines.
  Some projects have other requirements for commit messages, and
  may refuse changes if they are not followed.
  

With your changes committed to the local repository, it's time to send them to your copy on GitHub:

$ git push
  

We are able to use this short push command since we linked your local doc-corrections branch to your remote doc-corrections branch. If we hadn't, you'd have to issue:

$ git push origin doc-corrections
  

You can learn more about committing at https://git-scm.com/docs/git-commit.

Incorporating Upstream Changes

Prior to sending our corrections to the upstream project, it's a good idea to make sure you have any changes that have occurred upstream into your repository. To do that, we need to switch to the master branch, pull in changes from upstream, and then merge them into your doc-corrections branch:

$ git checkout master
  $ git pull upstream master
  $ git checkout doc-corrections
  $ git merge master
  

At this point git may tell you that there are conflicts. A conflict arises when the same file has been edited in both branches of the merge, master and doc-corrections in this case, such that git can't decide which change should "win." If this happens you will need to fix the conflicts and then issue a git commit.

With all of the changes incorporated, it's time to push them to your copy on GitHub: git push.

You can learn more about resolving conflicts at https://githowto.com/resolving_conflicts.

Sending Your Changes To Upstream

Now that your changes are pushed to your copy of the repository on GitHub, it's time to send them to the upstream repository owner(s) for review and possible inclusion. To do this, open your copy of the repository on GitHub. It'll be at a URL like https://github.com/your-username/pino.

With your repository open on GitHub in your browser, you should see a message suggesting that you send a "Pull Request" (PR) from your doc-corrections branch to the upstream master branch. Simply click the button in that message and you'll be taken to a form where you will can describe your PR. It will default to the last commit message in your branch, but you can change it. When you are happy with the PR message, submit the PR and wait.

GitHub is going to email the authors of the upstream project to let them know about your PR. They will review it and probably start a discussion with you, or just accept it if a discussion isn't necessary. Either way, you will receive emails keeping you informed of the process.

Once the PR has been resolved, you can remove your feature branch:

$ git checkout master
  $ git pull upstream master
  $ git branch -D doc-corrections
  

Summary

While it may seem like a complicated process, and in some ways it is, you should now be able to collaborate on a project that uses the Git SCM. In general, this is how most open source projects work. And once you have gone from fork to PR, the process shortens to simply staying synchronized, creating branches, and submitting PRs.

Don't be afraid to get involved. If the upstream people ask for changes, in most cases they are not insinuating anything about you personally. The simply want your changes to conform to the nature of their project so that your changes can be included. Or they have suggestions for improvement, so that your changes can be included.

A great place to get started with almost any project is with the documentation, just as we did in this article. If there's one thing every project wants it's someone willing to write documentation. As you get more comfortable, you will certainly start branching out from there.

By the way, I'm a maintainer on the Pino project. I look forward to seeing your PRs :)