How to rebase main git branch into a feature branch

Rebasing in Git means transferring the base of one branch onto another. When you rebase the feature branch with the main branch, you're moving the entire feature branch to begin on the tip of the main branch, incorporating all the new commits in the main. This can help resolve conflicts early and makes the history of your project linear and easier to follow.

Prerequisites

Before rebasing, make sure you have a clean working directory. This means that you don't have any files either untracked by Git (meaning that they exist locally but aren't tracked by Git), or have any uncommitted changes to existing files (meaning that you have changes to files locally but they haven't been added to the staging area, or pushed to the remote repository yet). Check this by running git status. If there are uncommitted changes, either commit them or stash them using git stash.

This command will temporarily stash these files for later use. Once you've rebased successfully and are satisfied with the changes, you can restore these stashed files back to the working directory by running git stash pop.

Step-by-step guide to rebase a feature branch with main

Now that we have a clean working directory, let's start the rebase.

Step 1: Update your local main branch

Purpose The goal here is to ensure that your local main branch is synchronized with the remote main branch. This is important because it ensures that any changes you're integrating into your feature branch are based on the latest version of your project, avoiding conflicts and simplifying the integration of new features.

Commands

git checkout main
git pull origin main

git checkout main

• What it does: This command switches your current working directory to the main branch. It updates your project files to reflect the state of the main branch, setting the stage for you to sync it with the remote repository.
• Under the hood: The checkout command adjusts the HEAD pointer to point to the main branch and updates the working directory to match the snapshot of the project at the latest commit on that branch.

git pull origin main

• What it does: This command fetches the latest changes from the main branch of the remote repository (typically called origin) and merges them into your local main branch.
• Under the hood: git pull is a compound command that first executes git fetch with the given branch (fetching updated data from your remote repository), followed by git merge, which integrates the remote main branch into your local main branch.

Step 2: Switch to your feature branch

Purpose Switching to your feature branch prepares you to rebase it onto the updated main branch. This is where you're developing new features or changes, isolated from the main branch until they're ready.

Commands

git checkout feature-branch

git checkout feature-branch

• What it does: Moves you from the main branch (or any other branch you might be on) to your feature branch.
• Under the Hood: Similar to the checkout to main, this changes your working directory and updates the files to reflect the state of feature-branch at its latest commit. It also adjusts the HEAD pointer to reference the feature-branch.

Step 3: Perform the rebase

Purpose Rebasing is a powerful tool for maintaining a clean project history. It allows you to take all the changes that were committed on one branch and replay them on another branch.

Commands

git rebase main

git rebase main

• What it does: This repositions the feature-branch to begin at the tip of the main branch. Essentially, it moves the starting point of feature-branch to the end of main, then applies each change made on the feature-branch one by one.
• Under the hood: git rebase changes the base of your feature branch from its current base to whatever main is now. This operation can be complex if there are conflicting changes between main and feature-branch. Git will pause the rebase and ask you to resolve any conflicts manually. Once all conflicts are resolved and all changes are applied, the feature branch will appear as if it was created based on the current end of the main branch.

Step 4: Resolve conflicts (if any)

During rebase, you may encounter conflicts. Git will stop at the first commit that causes conflict and give you the chance to resolve it. You can identify the files with conflicts using git status.

• Open the conflicted files and make the necessary changes.

• After resolving conflicts in a file, add it to the index using:

  Terminal

  git add <filename>
  
  

• Once all conflicts are resolved, continue the rebase process with:

  Terminal

  git rebase --continue
  
  

Repeat this process until all conflicts are resolved and the rebase is complete.

5. If needed, abort the rebase: If you find that the rebase is too complex or not going as planned, you can abort and return your branch to the state it was in before rebasing started:

   Terminal

   git rebase --abort
   
   

6. Push the changes: After the rebase is completed successfully, you'll need to push your changes to the remote feature branch. Since rebase changes the branch's history, you might need to use force push:

   Terminal

   git push origin feature-branch --force
   
   

   Caution: Be careful with force pushing, as it can overwrite changes in the remote branch. Ensure that no one else is working on the feature branch or that all team members are aware of the rebase.

Benefits of rebasing

• Simplified history: Rebasing creates a linear project history, which makes it easier to understand changes without the complexities of merge commits.
• Early conflict detection: By regularly rebasing the main branch into your feature branch, conflicts are detected and resolved sooner rather than later.

For further reading on git rebase see the official Git documentation.

Automatic rebasing with Graphite

The Graphite CLI automates the rebasing process, streamlining the management of stacked pull requests. Here's how it enhances your Git workflow:

• Automatic restacking of dependent branches: When you modify a commit on a parent branch, Graphite automatically restacks the child branches to maintain the correct sequence and dependencies.

• Seamless handling of partial merges: Upon partially merging a stack of pull requests, Graphite initiates a job that automatically rebases the remaining upstack branches onto the updated base. This ensures consistency and accurate code diffs on platforms like GitHub.

• Simplified local synchronization: To synchronize updates with your local repository, running gt sync pulls in the rebased branches from the remote and applies the changes locally, keeping your development environment aligned with the latest updates.

By automating these processes, Graphite CLI reduces manual intervention, minimizes the risk of conflicts, and allows you to focus more on coding rather than managing branch dependencies. For more information on the Graphite CLI, check out the documentation here.