Forks

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Whenever possible, it's recommended to work in a common Git repository and use branching strategies to manage your work. However, if you do not have write access for the repository you want to contribute to, you can create a fork.

A fork is a personal copy of the repository and all its branches, which you create in a namespace of your choice. Make changes in your own fork and submit them through a merge request to the repository you don't have access to.

The forked project uses a deduplication strategy to have a potentially smaller storage space than the source project. Forked projects can access the object pool connected to the source project.

Create a fork

Introduced in GitLab 16.6.

To fork an existing project in GitLab:

On the project's homepage, in the upper-right corner, select Fork ({fork}):
Optional. Edit the Project name.
For Project URL, select the namespace your fork should belong to.
Add a Project slug. This value becomes part of the URL to your fork. It must be unique in the namespace.
Optional. Add a Project description.
Select one of the Branches to include options:
- All branches (default).
- Only the default branch. Uses the --single-branch and --no-tags Git options.
Select the Visibility level for your fork. For more information about visibility levels, read Project and group visibility.
Select Fork project.

GitLab creates your fork, and redirects you to the new fork's page.

Update your fork

A fork can fall out of sync with its upstream repository, and require an update:

Ahead: Your fork contains new commits not present in the upstream repository. To sync your fork, create a merge request to push your changes to the upstream repository.
Behind: The upstream repository contains new commits not present in your fork. To sync your fork, pull the new commits into your fork.
Ahead and behind: Both the upstream repository and your fork contain new commits not present in the other. To fully sync your fork, create a merge request to push your changes up, and pull the upstream repository's new changes into your fork.

To sync your fork with its upstream repository, update it from the GitLab UI or the command line. GitLab Premium and Ultimate tiers can also automate updates by configuring forks as pull mirrors of the upstream repository.

From the UI

Introduced in GitLab 15.11 with a flag named synchronize_fork. Disabled by default, but enabled for projects in the gitlab-org/gitlab and gitlab-com/www-gitlab-com namespaces only.

Generally available in GitLab 16.0. Feature flag synchronize_fork removed.

Prerequisites:

The fork must be created from an unprotected branch in upstream repository.

To update your fork from the GitLab UI:

On the left sidebar, select Search or go to.
Select View all my projects.
Select the fork you want to update.
Below the dropdown list for branch name, find the Forked from ({fork}) information box to determine if your fork is ahead, behind, or both. In this example, the fork is behind the upstream repository:
If your fork is ahead of the upstream repository, select Create merge request to propose adding your fork's changes to the upstream repository.
If your fork is behind the upstream repository, select Update fork to pull changes from the upstream repository.
If your fork is ahead and behind the upstream repository, you can update from the UI available only if no merge conflicts are detected:
- If your fork contains no merge conflicts, you can select Create merge request to propose pushing your changes to the upstream repository, Update fork to pull changes down to your fork, or both. The type of changes in your fork determine which actions are appropriate.
- If your fork contains merge conflicts, update your fork from the command line.

From the command line

To update your fork from the command line, first ensure that you have configured an upstream remote repository for your fork:

Clone your fork locally, if you have not already done so. For more information, see Cloning Git repositories.
View the remotes configured for your fork:
```
git remote -v
```

If your fork does not have a remote pointing to the original repository, use one of these examples to configure a remote called upstream:

# Use this line to set any repository as your upstream after editing <upstream_url>
git remote add upstream <upstream_url>

# Use this line to set the main GitLab repository as your upstream
git remote add upstream https://gitlab.com/gitlab-org/gitlab.git

After ensuring your local copy has the extra remote configured, you are ready to update your fork.

In your local copy, ensure you have checked out the default branch, replacing main with the name of your default branch:
```
git checkout main
```
If Git identifies unstaged changes, commit or stash them before continuing.
Fetch the changes to the upstream repository:
```
git fetch upstream
```
Pull the changes into your fork, replacing main with the name of the branch you are updating:
```
git pull upstream main
```
Push the changes to your fork repository on the server (GitLab.com or self-managed):
```
git push origin main
```

With repository mirroring

DETAILS: Tier: Premium, Ultimate Offering: GitLab.com, Self-managed, GitLab Dedicated

A fork can be configured as a mirror of the upstream if all these conditions are met:

Your subscription is Premium or Ultimate.
You create all changes in branches (not main).
You do not work on merge requests for confidential issues, which requires changes to main.

Repository mirroring keeps your fork synced with the original repository. This method updates your fork once per hour, with no manual git pull required. For instructions, read Configure pull mirroring.

WARNING: With mirroring, before approving a merge request, you are asked to sync. You should automate it.

Merge changes back upstream

When you are ready to send your code back to the upstream project, create a merge request. For Source branch, choose your forked project's branch. For Target branch, choose the original project's branch.

NOTE: When creating a merge request, if the forked project's visibility is more restrictive than the parent project (for example the fork is private, the parent is public), the target branch defaults to the forked project's default branch. This prevents potentially exposing the private code of the forked project.

Then you can add labels, a milestone, and assign the merge request to someone who can review your changes. Then select Submit merge request to conclude the process. When successfully merged, your changes are added to the repository and branch you're merging into.

Unlink a fork

Removing a fork relationship unlinks your fork from its upstream project. Your fork then becomes an independent project.

Prerequisites:

You must be a project owner to unlink a fork.

WARNING: If you remove a fork relationship, you can't send merge requests to the source. If anyone has forked your project, their fork also loses the relationship. To restore the fork relationship, use the API.

To remove a fork relationship:

On the left sidebar, select Search or go to and find your project.
Select Settings > General.
Expand Advanced.
In the Remove fork relationship section, select Remove fork relationship.
To confirm, enter the project path and select Confirm.

When you unlink a fork that uses a hashed storage pool to share objects with another repository:

All objects are copied from the pool into your fork.
After the copy process completes, no further updates from the storage pool are propagated to your fork.

Troubleshooting

Error: `An error occurred while forking the project. Please try again`

This error can be due to a mismatch in instance runner settings between the forked project and the new namespace. See Forks in the Runner documentation for more information.

Removing fork relationship fails

If removing the fork through the UI or API is not working, you can attempt the fork relationship removal in a Rails console session:

p = Project.find_by_full_path('<project_path>')
u = User.find_by_username('<username>')
Projects::UnlinkForkService.new(p, u).execute