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Code Owners (STARTER)

Introduction

When contributing to a project, it can often be difficult to find out who should review or approve merge requests. Additionally, if you have a question over a specific file or code block, it may be difficult to know who to find the answer from.

GitLab Code Owners is a feature to define who owns specific files or paths in a repository, allowing other users to understand who is responsible for each file or path.

Why is this useful?

Code Owners allows for a version controlled single source of truth file outlining the exact GitLab users or groups that own certain files or paths in a repository. Code Owners can be utilized in the merge request approval process which can streamline the process of finding the right reviewers and approvers for a given merge request.

In larger organizations or popular open source projects, Code Owners can also be useful to understand who to contact if you have a question that may not be related to code review or a merge request approval.

How to set up Code Owners

You can use a CODEOWNERS file to specify users or shared groups that are responsible for certain files in a repository.

You can choose and add the CODEOWNERS file in three places:

  • To the root directory of the repository
  • Inside the .gitlab/ directory
  • Inside the docs/ directory

The CODEOWNERS file is scoped to a branch, which means that with the introduction of new files, the person adding the new content can specify themselves as a code owner, all before the new changes get merged to the default branch.

When a file matches multiple entries in the CODEOWNERS file, the users from last pattern matching the file are displayed on the blob page of the given file. For example, you have the following CODEOWNERS file:

README.md @user1

# This line would also match the file README.md
*.md @user2

The user that would show for README.md would be @user2.

Approvals by Code Owners

Once you've set Code Owners to a project, you can configure it to be used for merge request approvals:

NOTE: Note: Developer or higher permissions are required in order to approve a merge request.

Once set, Code Owners are displayed in merge requests widgets:

MR widget - Code Owners

While the CODEOWNERS file can be used in addition to Merge Request Approval Rules it can also be used as the sole driver of merge request approvals (without using Approval Rules). To do so, create the file in one of the three locations specified above and set the code owners as required approvers for protected branches. Use the syntax of Code Owners files to specify the actual owners and granular permissions.

Using Code Owners in conjunction with Protected Branches Approvals will prevent any user who is not specified in the CODEOWNERS file from pushing changes for the specified files/paths, even if their role is included in the Allowed to push column. This allows for a more inclusive push strategy, as administrators don't have to restrict developers from pushing directly to the protected branch, but can restrict pushing to certain files where a review by Code Owners is required.

The syntax of Code Owners files

Files can be specified using the same kind of patterns you would use in the .gitignore file followed by the @username or email of one or more users or by the @name of one or more groups that should be owners of the file. Groups must be added as members of the project, or they will be ignored.

Starting in GitLab 13.0, you can now specify groups or subgroups from the project's group hierarchy as potential code owners.

For example, consider the following hierarchy for a given project:

group >> sub-group >> sub-subgroup >> myproject >> file.md

Any of the following groups would be eligible to be specified as code owners:

  • @group
  • @group/sub-group
  • @group/sub-group/sub-subgroup

In addition, any groups that have been invited to the project using the Members tool will also be recognized as eligible code owners.

The order in which the paths are defined is significant: the last pattern that matches a given path will be used to find the code owners.

Starting a line with a # indicates a comment. This needs to be escaped using \# to address files for which the name starts with a #.

Example CODEOWNERS file:

# This is an example of a code owners file
# lines starting with a `#` will be ignored.

# app/ @commented-rule

# We can specify a default match using wildcards:
* @default-codeowner

# We can also specify "multiple tab or space" separated codeowners:
* @multiple @code @owners

# Rules defined later in the file take precedence over the rules
# defined before.
# This will match all files for which the file name ends in `.rb`
*.rb @ruby-owner

# Files with a `#` can still be accessed by escaping the pound sign
\#file_with_pound.rb @owner-file-with-pound

# Multiple codeowners can be specified, separated by spaces or tabs
# In the following case the CODEOWNERS file from the root of the repo
# has 3 code owners (@multiple @code @owners)
CODEOWNERS @multiple @code @owners

# Both usernames or email addresses can be used to match
# users. Everything else will be ignored. For example this will
# specify `@legal` and a user with email `[email protected]` as the
# owner for the LICENSE file
LICENSE @legal this_does_not_match [email protected]

# Group names can be used to match groups and nested groups to specify
# them as owners for a file
README @group @group/with-nested/subgroup

# Ending a path in a `/` will specify the code owners for every file
# nested in that directory, on any level
/docs/ @all-docs

# Ending a path in `/*` will specify code owners for every file in
# that directory, but not nested deeper. This will match
# `docs/index.md` but not `docs/projects/index.md`
/docs/* @root-docs

# This will make a `lib` directory nested anywhere in the repository
# match
lib/ @lib-owner

# This will only match a `config` directory in the root of the
# repository
/config/ @config-owner

# If the path contains spaces, these need to be escaped like this:
path\ with\ spaces/ @space-owner