June 3, 2024

Mastering CODEOWNERS: Streamline Code Ownership in Your Git Repository

Table of Contents

Key takeaway

The CODEOWNERS file ensures only designated users or teams can approve changes to specific code areas, enhancing security and accountability.

In modern software development workflows, having clear ownership of different sections of your codebase is essential. The CODEOWNERS file streamlines the code review process and enhances security, accountability, and efficiency. In this blog, you'll explore the CODEOWNERS file and discover how it can effectively streamline code ownership in your Git repository.

Understanding the CODEOWNERS File

A CODEOWNERS file is a simple yet powerful configuration file that allows you to declare the users or teams responsible for specific files or directories within your Git repository. This file helps ensure that code changes are reviewed by the appropriate stakeholders. In a monorepo setting, CODEOWNERS is particularly valuable as it helps manage ownership and review processes across multiple projects within a single repository, ensuring the right teams are accountable for their respective code areas.

In a CODEOWNERS file for Harness Code Repository and Gitness, you specify file patterns along with the email address associated with the Harness user profile of the code owners. These patterns can include wildcard characters to match multiple files or directories, providing flexibility in defining ownership across your codebase.

Why you need CODEOWNERS file

Defining CODEOWNERS establishes a safeguard, ensuring that only designated users or teams can approve changes to specific areas of the codebase, enhancing security.

In the case of the Harness Code Repository, for example, code owners aren't automatically added as reviewers on your pull requests (PRs). Although CODEOWNERS are linked to PRs, they're not automatically assigned as reviewers. This approach is designed to prevent reviewer spam, particularly for changes that may not require review from all CODEOWNERS. This balance between associating CODEOWNERS with PRs and manual addition as reviewers provides flexibility while maintaining control over the review process.

You have the flexibility to request reviews from individual CODEOWNERS as needed. If a CODEOWNER independently chooses to review a PR, they are added as a reviewer for record-keeping purposes, similar to any independent review. Additionally, if you've enabled the CODEOWNER branch rule, where review from code owners is required, CODEOWNERS are treated as a policy checked against PR reviewers. If none of the reviewers are CODEOWNERS, merging is blocked. 

Here is an example of a CODEOWNERS branch rule. In the next part of this blog series, there will be a deeper dive on branch rules.

Image: Branch Rules for CODEOWNERS File

Syntax and Usage

Store your CODEOWNERS file in the root of your code repo, at docs/CODEOWNERS, or under .harness. Let's break down the structure using some examples for the Harness Code Repository:

Global Owner: Assign a global owner for all files in the repository.

# Harness ---

# Assign a global owner for all files
* @email

Specific File Owners: Specify multiple owners for a particular file by listing their email addresses or usernames.

# Specify multiple owners for a specific file
Gemfile.lock @email1 @email2

Subdirectory Owners: Define ownership for entire subdirectories by specifying the directory path followed by the owner's email address or username.

# Define owners for subdirectories
/some_directory/ @email
/some_directory_2/ @email1 @email2

Workspace Owner: Assign ownership for a specific workspace file.

# Assign an owner for a workspace file
WORKSPACE @email

Wildcards: Utilize wildcards to assign ownership to files matching specific patterns, such as all files within the "src" directory or files with a ".lock" extension.

# Utilize wildcards for flexible ownership
**/src/** @email
*.lock @email

NOTE: CODEOWNERS syntax for your particular Git provider might vary so edits might be necessary when migrating your repository to Harness Code.

By leveraging this syntax, you can effectively manage ownership across your codebase, ensuring that the right individuals or teams are responsible for reviewing changes in relevant areas.

Best Practices

To make the most out of the CODEOWNERS file in your Git repository, consider the following best practices:

  • Granularity: Define ownership at an appropriate level of granularity to ensure effective code review coverage without overwhelming reviewers.
  • Consistency: Maintain consistency in the file patterns and ownership assignments to avoid confusion among contributors.
  • Documentation: Document the purpose and structure of the CODEOWNERS file within your repository to guide contributors on its usage.
  • Testing: Regularly test and validate the CODEOWNERS file to ensure that ownership assignments are accurate and up-to-date.

Next Steps

The CODEOWNERS file is a valuable asset for managing code ownership and streamlining the code review process in your Git repository. By leveraging its capabilities and adhering to best practices, you can ensure that changes are reviewed by the right people, fostering collaboration and maintaining code quality. Start mastering CODEOWNERS, repository security, and other best practices for Harness Code Repository by visiting the documentation.

Code Repository
Gitness