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tech 10 September 2026

Review a Pull Request by Booting It

Discover how trynix-preview allows you to test and validate a pull request directly in your browser. Say goodbye to complex clones and builds.

Article inspired by the original source
Review a pull request by booting it ↗ fzakaria.com

Introduction

In the world of software development, every minute counts. When it comes to reviewing a pull request (PR), the process can often be long and tedious, especially if you have to manually clone, build, and test the code. But imagine a world where you could simply "boot" a PR to test it directly in your browser. That's exactly what trynix-preview, a revolutionary GitHub action, offers.

What is trynix-preview?

Trynix-preview is a GitHub action that, when integrated into your workflow, comments a link on a PR. This link allows you to boot the PR's build in your browser via [trynix.dev](https://trynix.dev). No servers required, just your browser. It's a paradigm shift that drastically simplifies PR review.

Real-World Example

Take the sqlelf project, for instance. When a PR is submitted, trynix-preview leaves a comment containing a link. Click it, and a Linux machine boots in your tab with the PR's code already on PATH. No need to clone, build, or configure servers.

How Does It Work?

To use trynix-preview, you first need to ensure the path is already built and cached. Integrating the action is simple: just a few lines in your GitHub workflow file.

```yaml # Set up Cachix as our Nix cache.

  • uses: cachix/cachix-action@v17

with: name: sqlelf authToken: ${{ secrets.CACHIX_AUTH_TOKEN }}

# Build the pull request's code and push it to the cache.

  • run: nix build .#default
  • uses: fzakaria/trynix@v1

with: cache: https://sqlelf.cachix.org publicKey: sqlelf.cachix.org-1:MLnjolA9AsKscTOJKDSA+ZAcgIK8BwZA574j4+Cs2bg= attrs: .#default ```

The action builds nothing and publishes nothing. It simply provides the store paths via nix eval and hands the cache's URL and public key to the browser.

Security and Best Practices

For security reasons, enable allow-unsafe-pr-checkout: true in the actions/checkout step because the workflow runs on a fork's PR. It is also recommended to use a private, segregated cache for PR builds to prevent a fork from pushing to your main cache.

Current Limitations

Though trynix-preview is a significant advancement, it's not yet ready to replace all existing CI products. Performance for large binaries can be poor, with boot times of 1 to 2 minutes in some cases.

Conclusion

Trynix-preview transforms how we review PRs by eliminating tedious steps and enabling quick validation directly from the browser. Ready to revolutionize your code review? [Let's discuss your project in 15 minutes.](#)

References and Resources

  • [trynix.dev](https://trynix.dev)
  • [Cachix](https://cachix.org)
GitHub actions trynix-preview pull request code review automation
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