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Product Overview of Gerrit
Gerrit is a web-based, open-source code review tool built on top of the Git version control system. It is designed to streamline the code review process, ensuring high-quality code and fostering collaboration among developers.
What Gerrit Does
Gerrit allows developers to push commits into a special review process rather than directly pushing them to a repository. This approach enables thorough code reviews before changes are merged into the main codebase. Originally developed at Google, Gerrit has been open-sourced for broader adoption and is now used by numerous organizations, including Android, Eclipse, and the Wikimedia Foundation.
Key Features and Functionality
Code Review Process
Gerrit facilitates a structured code review process where developers can upload changes, and peers can review these changes using a web-based interface. The process involves:
- Pushing Changes: Developers push their commits to Gerrit using special references (e.g., `refs/for/
`), which creates a change in the Gerrit UI. - Review and Feedback: Reviewers can view changes side-by-side or in a unified diff view, add inline comments, and provide feedback. Comments can be saved as drafts and edited before publication.
- Approval and Merging: Changes are approved or rejected based on review feedback. A change can be updated iteratively by the developer, creating multiple patch sets until it meets the required standards. Once approved, the change is merged into the target branch.
Patch-Based Review
Gerrit treats each commit as a proposed patch set, which can be updated iteratively. This allows for continuous improvement of the code based on feedback from reviewers.
Inline and Side-by-Side Diffs
Reviewers can view changes in side-by-side or unified diff views, making it easier to compare and comment on the code. Inline comments can be added directly to specific lines of code.
Gatekeeping and Approval Labels
Gerrit uses a label-based approval system, such as `Code-Review` and `Verified`, to ensure that only rigorously vetted code is merged. Labels like 2, 1, 0, -1, and -2 help in categorizing the level of approval or rejection. For example, 2 indicates approval, while -2 is a strong veto.
Integration with CI/CD Systems
Gerrit integrates seamlessly with Continuous Integration/Continuous Deployment (CI/CD) systems like Jenkins. This automation helps in verifying builds, tests, code coverage, and style checks, reducing the manual workload for reviewers.
Fine-Grained Access Control
Gerrit offers a granular permission model, allowing administrators to set permissions at both the project and branch levels. This ensures that only authorized contributors can merge changes or give final approvals.
Repository and Branch Management
Gerrit can manage multiple repositories and branches within each project. It stores changes as references in the `refs/changes/` namespace, allowing for efficient tracking and management of pending changes.
Collaboration and Knowledge Sharing
The code review process in Gerrit fosters collaboration and knowledge sharing among team members. Newcomers can learn from experienced developers by reviewing their code, promoting shared code ownership and enhancing overall code quality and consistency.
Additional Capabilities
- Web Frontend: Gerrit provides a lightweight web-based interface for reviewing every commit, eliminating the need for additional command-line tools.
- Plugins and Hooks: Gerrit has a wide ecosystem of plugins and hooks that can add custom functionality, such as replication to external Git servers and custom automation.
- SSH Support: Gerrit includes SSH support using Apache Mina SSHD software, facilitating secure connections.
In summary, Gerrit is a powerful tool for code review and repository management, integrating tightly with Git to ensure high-quality code and efficient collaboration among developers. Its robust features and flexible architecture make it an essential component of many DevOps workflows.
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