12 Collaboration across Branches

Let’s say you’re on a team of coders and you all have access to the same GitHub repo. (One person on the team owns the repo, and they’ve added you all as collaborators¹⁶.)

I’m going to use the term collaborator to mean “someone to whom you have granted write access to your repo”.

How can you all structure your work so that you’re minimizing conflicts?

There are a number of ways to do this.

• Everyone is a collaborator on the repo, and:
  • Everyone uses the same branch, probably main, or:
  • Everyone uses their own remote tracking branch and periodically merges with the main branch, or:
  • Everyone uses their own remote tracking branch and periodically merges with a development branch, which itself is periodically merged into main for each official release.
• Or everyone has their own repo (and are not collaborators on the same repo), and:
  • Everyone uses pull requests or other synchronization methods to get their repos merged into the other devs’.

We’ll look at the first few ways in this chapter, but we’ll save pull requests for later.

There’s no one-size-fits-all approach to teamwork with Git, and the methods outlined below can be mixed and matched with local topic branches, or people having multiple remote tracking branches, or whatever. Often management will have an approach they want to use for collaboration which might be one of the ones in this section, or maybe it’s a variant, or maybe its something completely different.

In any case, the best strategy for you, the learner, is to just be familiar with the tools (branching, merging, conflict resolution, pushing, pulling, remote tracking branches) and use them for effect where it makes the most sense.

And when you’re first starting out, your intuition about “where it makes the most sense” might not be dead-on, but it probably won’t be lethal and you’ll figure it out in the school of hard knocks.

“Oh great. Another f—ing learning experience.”
       —Actual quote from my mother

12.1 Communication and Delegation

Git can’t save you from poor communication. The only way to minimize conflicts in a shared project to communicate with your team and clearly assign different tasks to people in a non-conflicting way.

Two people shouldn’t generally be editing the same part of the same file, or even any part of the same file. That’s more of a guideline than a rule, but if you follow it, you will never have a merge conflict.

As we’ve seen, it’s not the end of the world if there is a merge conflict, but life sure is easier if they’re just avoided.

Takeaway: without good communication and a good distribution of work on your team, you’re doomed. Make a plan where no one is stepping on toes, and stick to it.

12.2 Approach: Everyone Uses One Branch

This is really easy. Everyone has push access to the repo and does all their work on the main branch.

Benefits:

• Super simple to set up.
• Conceptually not much to juggle.
• All work instantly available to all collaborators upon push.

Drawbacks:

• More potential for merge conflicts.
• Unless you’re rebasing (more on that later), you’ll have a lot of merge commits.
• You can’t push non-working code since it will break everything for everyone else.

Initial setup:

• One person makes the GitHub repo
• The owner of the GitHub repo adds all the team members as collaborators.
• Everyone clones the repo.

Workflow:

• Work is delegated to all collaborators. The work should be as non-overlapping as possible.
• Everyone periodically pulls main and resolves any merge conflicts.
• Everyone pushes their work to main.

In real life, this approach is probably only used on very small teams, e.g. three people at most, with frequent and easy communication between all members. If you’re working on a small team in school, it could very well be enough, but I’d still recommend trying a different approach just for the experience.

The other approaches are not that much more complex, and give you a lot more flexibility.

12.3 Approach: Everyone Uses Their Own Branch

In this scenario, we treat main as the working code, and we treat contributors’ branches as where work is done. When a contributor gets their code working, they merge it back into main.

Benefits:

• You get to work on your own branch without worrying about messing up other people’s work.
• You can commit non-working code since no one else can see it. (You might be wrapping up the work day and want to push some incomplete code for a backup, for example.)
• Less merge conflict potential since fewer merges are happening than if everyone were committing to main.

Drawbacks:

• If your branch diverges too far from main, merging might become painful.
• Unless you’re rebasing, the incremental work on your branch might “pollute” the commit history on main with a lot of tiny commits.

Initial setup:

• One person makes the GitHub repo
• The owner of the GitHub repo adds all the team members as collaborators.
• Everyone clones the repo.
• Everyone makes their own branch, possibly naming it after themselves.
• Everyone pushes their branch to GitHub, making them remote-tracking branches. (We do this so that your work is effectively backed up on GitHub when you push it.)

Workflow:

• Work is delegated to all collaborators. The work should be as non-overlapping as possible.
• As collaborators finish their tasks, they will:
  • Test everything on their branch.
  • Merge the latest main into their branch; do a pull to make sure you have it. (The collaborator might already have the latest main if no one else has merged into it, which will cause Git to say there’s nothing to do. This is fine.)
  • Test everything, and fix it if necessary.
  • Merge their functioning branch into main.
  • Push.
    • If someone else has modified main while you were testing, Git will complain that you have to pull before you can push. If there’s a conflict at this point, you’ll have to resolve, test, and push it. And you’ll have to merge main back into your branch so that your branch is up-to-date.

The result will look something like Figure 12.1 to start, where all the collaborators have made their own branches off of main.

Let’s say Chris (on branch chris) finishes up their work and wants other contributors to be able to see it. It’s time to merge into main, as we graphically see in Figure 12.2.

After that, other contributors looking at main will see the changes.

12.4 Approach: Everyone Merges to the Dev Branch

In this scenario, we treat main as the published code that we’re going to distribute, often tagged with a release version number, and we treat a dev branch as the working, unreleased code. And, as in the previous scenario, everyone has their own branches they’re developing on.

The idea is basically we’re going to have two versions of the working code:

1. The public, released version that’s on main.
2. The private, internal version that’s on dev.

And then, of course, we’ll have one branch per collaborator.

Another way of thinking about it is that we’re going to have our internal build on dev that is good for testing and then, when it’s all ready, we’ll “bless” it and merge it into main.

So there will be a lot of merges into dev from all the developer branches, and then every so often there will be a merge from dev into main.

The developers will never directly merge into main! Usually that is performed by someone in a managerial role.

Overall the process works as in Figure 12.3. This is a busy image, but notice how Bob and Alice are only merging their work into the dev branch, and then every so often, their manager merges the dev branch into main and tags that commit with a release number. (More on tagging later.)

Benefits:

• All the benefits of everyone having their own branch.
• You have an internal branch from which you can make complete builds for internal or external testing.

Drawbacks:

• A little more complexity and management.
• If your branch diverges too far from dev, merging might become painful.
• Unless you’re rebasing, the incremental work on your branch might “pollute” the commit history on dev with a lot of tiny commits.

Initial setup:

• One person makes the GitHub repo
• The owner of the GitHub repo adds all the team members as collaborators.
• Everyone clones the repo.
• Everyone makes their own branch, possibly naming it after themselves.
• Everyone pushes their branch to GitHub, making them remote-tracking branches. (We do this so that your work is effectively backed up on GitHub when you push it.)

Workflow:

• Work is delegated to all collaborators. The work should be as non-overlapping as possible.
• As collaborators finish their tasks, they will:
  • Test everything on their branch.
  • Merge the latest dev into their branch; do a pull to make sure you have it. (The collaborator might already have the latest dev if no one else has merged into it, which will cause Git to say there’s nothing to do. This is fine.)
  • Test everything, and fix it if necessary.
  • Merge their functioning branch into dev.
  • Push.
    • If someone else has modified dev while you were testing, Git will complain that you have to pull before you can push. If there’s a conflict at this point, you’ll have to resolve, test, and push it. And you’ll have to merge dev back into your branch so that your branch is up-to-date.

Managerial Workflow:

• Coordinate with all devs to get a candidate release in dev tested out and ready.
• Merge that candidate release (some commit) from dev into main.
• Tag the main commit with some version number, optionally.