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Getting started with Merge Requests

A Merge Request (MR) is the basis of GitLab as a code collaboration and version control.

When working in a Git-based platform, you can use branching strategies to collaborate on code.

A repository is composed by its default branch, which contains the major version of the codebase, from which you create minor branches, also called feature branches, to propose changes to the codebase without introducing them directly into the major version of the codebase.

Branching is especially important when collaborating with others, avoiding changes to be pushed directly to the default branch without prior reviews, tests, and approvals.

When you create a new feature branch, change the files, and push it to GitLab, you have the option to create a Merge Request, which is essentially a request to merge one branch into another.

The branch you added your changes into is called source branch while the branch you request to merge your changes into is called target branch.

The target branch can be the default or any other branch, depending on the branching strategies you choose.

In a merge request, beyond visualizing the differences between the original content and your proposed changes, you can execute a significant number of tasks before concluding your work and merging the merge request.

You can watch our GitLab Flow video for a quick overview of working with merge requests.

How to create a merge request

Learn the various ways to create a merge request.

What you can do with merge requests

When you start a new merge request, you can immediately include the following options, or add them later by clicking the Edit button on the merge request's page at the top-right side:

After you have created the merge request, you can also:

Many of these can be set when pushing changes from the command line, with Git push options.

See also other features associated to merge requests.

Assignee

Choose an assignee to designate someone as the person responsible for the first review of the merge request. Open the drop down box to search for the user you wish to assign, and the merge request will be added to their assigned merge request list.

Multiple assignees (STARTER)

Introduced in GitLab Starter 11.11.

Multiple people often review merge requests at the same time. GitLab allows you to have multiple assignees for merge requests to indicate everyone that is reviewing or accountable for it.

multiple assignees for merge requests sidebar

To assign multiple assignees to a merge request:

  1. From a merge request, expand the right sidebar and locate the Assignees section.
  2. Click on Edit and from the dropdown menu, select as many users as you want to assign the merge request to.

Similarly, assignees are removed by deselecting them from the same dropdown menu.

It is also possible to manage multiple assignees:

Reviewer

WARNING: This feature might not be available to you. Check the version history note above for details.

Requesting a code review is an important part of contributing code. However, deciding who should review your code and asking for a review are no easy tasks. Using the "assignee" field for both authors and reviewers makes it hard for others to determine who's doing what on a merge request.

GitLab Merge Request Reviewers easily allow authors to request a review as well as see the status of the review. By selecting one or more users from the Reviewers field in the merge request's right-hand sidebar, the assigned reviewers will receive a notification of the request to review the merge request.

This makes it easy to determine the relevant roles for the users involved in the merge request, as well as formally requesting a review from a peer.

To request it, open the Reviewers drop-down box to search for the user you wish to get a review from.

Enable or disable Merge Request Reviewers (CORE ONLY)

Merge Request Reviewers is under development but ready for production use. It is deployed behind a feature flag that is enabled by default. GitLab administrators with access to the GitLab Rails console can opt to disable it.

To enable it:

# For the instance
Feature.enable(:merge_request_reviewers)
# For a single project
Feature.enable(:merge_request_reviewers, Project.find(<project id>))

To disable it:

# For the instance
Feature.disable(:merge_request_reviewers)
# For a single project
Feature.disable(:merge_request_reviewers, Project.find(<project id>))

Approval Rule information for Reviewers (STARTER)

WARNING: This feature might not be available to you. Check the version history note above for details.

When editing the Reviewers field in a new or existing merge request, GitLab displays the name of the matching approval rule below the name of each suggested reviewer. Code Owners are displayed as Code Owner without group detail. We intend to iterate on this feature in future releases.

This example shows reviewers and approval rules when creating a new merge request:

Reviewer approval rules in new/edit form

This example shows reviewers and approval rules in a merge request sidebar:

Reviewer approval rules in sidebar

Enable or disable Approval Rule information for Reviewers (STARTER ONLY)

Merge Request Reviewers is under development and ready for production use. It is deployed behind a feature flag that is enabled by default. GitLab administrators with access to the GitLab Rails console can opt to disable it.

To enable it:

# For the instance
Feature.enable(:reviewer_approval_rules)
# For a single project
Feature.enable(:reviewer_approval_rules, Project.find(<project id>))

To disable it:

# For the instance
Feature.disable(:reviewer_approval_rules)
# For a single project
Feature.disable(:reviewer_approval_rules, Project.find(<project id>))

Merge requests to close issues

If the merge request is being created to resolve an issue, you can add a note in the description which sets it to automatically close the issue when merged.

If the issue is confidential, you may want to use a different workflow for merge requests for confidential issues to prevent confidential information from being exposed.

Deleting the source branch

When creating a merge request, select the Delete source branch when merge request accepted option, and the source branch is deleted when the merge request is merged. To make this option enabled by default for all new merge requests, enable it in the project's settings.

This option is also visible in an existing merge request next to the merge request button and can be selected or deselected before merging. It is only visible to users with Maintainer permissions in the source project.

If the user viewing the merge request does not have the correct permissions to delete the source branch and the source branch is set for deletion, the merge request widget displays the Deletes source branch text.

Delete source branch status

Recommendations and best practices for Merge Requests

  • When working locally in your branch, add multiple commits and only push when you're done, so GitLab runs only one pipeline for all the commits pushed at once. By doing so, you save pipeline minutes.
  • Delete feature branches on merge or after merging them to keep your repository clean.
  • Take one thing at a time and ship the smallest changes possible. By doing so, reviews are faster and your changes are less prone to errors.
  • Do not use capital letters nor special chars in branch names.