How to Use the Command 'nixpkgs-review' (with examples)

The nixpkgs-review command is an essential tool for developers working within the NixOS ecosystem. It simplifies the process of reviewing changes in the Nix Packages collection (nixpkgs) by automating the build and review process for pull requests, local commits, and staged changes. When a build is successful, it even initiates a nix-shell with all the built packages, allowing developers to test their packages in isolation.

Use case 1: Building Changed Packages in a Specified Pull Request

Code:

nixpkgs-review pr pr_number|pr_url

Motivation:

The motivation behind building changed packages in a specified pull request is to ensure that the modifications proposed in a pull request do not break existing functionalities and work as intended. By building these packages, developers can verify the changes locally before merging them into the main branch, which helps maintain the integrity and stability of the repository.

Explanation:

• nixpkgs-review: This is the command-line tool used to review changes in the nixpkgs repository.
• pr: This flag specifies that you are targeting a pull request.
• pr_number|pr_url: You can replace this with the actual pull request number or URL you want to review. This tells nixpkgs-review which specific pull request contains the changes you want to build and assess.

Example Output:

$ nixpkgs-review pr 12345
$ git worktree add /path/to/review
$ nix-build /path/to/review
Packages built successfully.
Starting a nix-shell session with built packages...

Use case 2: Building Changed Packages and Posting a Comment with a Report

Code:

nixpkgs-review pr --post-result pr_number|pr_url

Motivation:

This use case is particularly useful for developers who want to automate the process of not only building and testing the changes but also communicating the results back to the pull request. By posting a comment with the report, other collaborators can quickly see the results and act accordingly, streamlining the review process and facilitating better team collaboration.

Explanation:

• nixpkgs-review: Specifies the use of the Nix package review tool.
• pr: Indicates that the command is targeting a pull request.
• --post-result: This option automatically posts the build report as a comment on the pull request. It requires authentication through a token set up in hub, gh, or via the GITHUB_TOKEN environment variable.
• pr_number|pr_url: The specific pull request number or URL of the PR to be reviewed and reported.

Example Output:

$ nixpkgs-review pr --post-result 67890
$ Posting build results to PR...
$ Comment posted with results: success

Use case 3: Building Changed Packages and Printing a Report

Code:

nixpkgs-review pr --print-result pr_number|pr_url

Motivation:

Printing a report upon building the changed packages enables developers to have immediate insights into the results without having to navigate through the GitHub interface. This local feedback loop can be beneficial for quick checks and for those who prefer command-line outputs over a web interface.

Explanation:

• nixpkgs-review: Denotes the use of the Nix package review tool.
• pr: Specifies that the command is directed toward a pull request.
• --print-result: This flag prompts the tool to print the build results directly in the terminal for quick accessibility.
• pr_number|pr_url: The pull request number or URL denoting which set of changes to review and report.

Example Output:

$ nixpkgs-review pr --print-result 24680
$ Build results:
  Success: package1, package2
  Failed: package3

Use case 4: Building Changed Packages in a Local Commit

Code:

nixpkgs-review rev HEAD

Motivation:

This scenario is aimed at developers who want to review changes they’ve made locally before those changes are committed and pushed to a remote repository. It ensures that the local modifications are stable and do not introduce any new bugs or issues, providing an additional layer of quality assurance before making changes publicly available.

Explanation:

• nixpkgs-review: Calls the package review tool.
• rev: Indicates that you are reviewing a particular revision or commit.
• HEAD: The pointer to the latest commit in the current branch, representing the latest state of your changes locally.

Example Output:

$ nixpkgs-review rev HEAD
$ Building packages...
$ All packages built successfully. Entering nix-shell...

Use case 5: Building Changed Packages That Haven’t Been Committed Yet

Code:

nixpkgs-review wip

Motivation:

The need to review work-in-progress (WIP) changes allows a developer to identify potential issues with code that is still under development. By building uncommitted changes, developers can ensure that ongoing development is not causing regressions or new failures in the package ecosystem.

Explanation:

• nixpkgs-review: Initiates the review tool for nixpkgs.
• wip: Stands for “work in progress,” prompting the tool to build current uncommitted changes.

Example Output:

$ nixpkgs-review wip
$ Building WIP changes...
$ Build failed for packageXYZ. Fix errors before committing.

Use case 6: Building Changed Packages That Have Been Staged

Code:

nixpkgs-review wip --staged

Motivation:

This use case targets staged changes, which are those that have been set up in preparation for a commit. Reviewing these changes specifically helps developers ensure that what they’re about to commit and share is well-validated and free from issues, adding a layer of precision and care to the process.

Explanation:

• nixpkgs-review: Engages the nixpkgs review tool.
• wip: Indicates work in progress, capturing all updates.
• --staged: A flag indicating to only consider changes that have been staged for the next commit.

Example Output:

$ nixpkgs-review wip --staged
$ Testing staged changes...
$ Staged packages built successfully. Ready to commit.

Conclusion:

The nixpkgs-review command is a powerful tool that provides various functionalities to ensure high-quality integration of changes into the NixOS package repository. It allows developers to build, test, and report on package changes through multiple versatile options, making the review process more efficient and standardized. Whether you’re dealing with remote pull requests or local changes, nixpkgs-review enhances code integrity and facilitates collaborative development.