Using renovate to update Nix flakes

Renovate is an essential tool for managing dependencies automatically. Integrating Renovate with your Nix Flake-based project ensures timely updates, maintains security, and keeps your project streamlined. Here’s how to onboard your repository and configure Renovate effectively.

Step-by-Step Configuration

Enable Renovate in GitHub:

• Navigate to the Renovate GitHub App and enable it for your repository.

• Prepare the Configuration File:

  • Create a configuration file named renovate.json.

  • For better repository clarity, place it within the .github folder, which prevents clutter by hiding this configuration at the repository root.

My example Configuration (.github/renovate.json)

{
  "$schema": "https://docs.renovatebot.com/renovate-schema.json",
  "extends": [
    "config:recommended",
    ":semanticCommitTypeAll(chore)"
  ],
  "lockFileMaintenance": {
    "enabled": true,
    "extends": [
      "schedule:weekly"
    ]
  },
  "nix": {
    "enabled": true
  },
  "ignoreDeps": [
    "stable",
    "wallpapers-nix"
  ]
}

Configuration Explained

• config:recommended: This base configuration applies sensible defaults, enabling dependency updates and grouping rules for easier management.

• :semanticCommitTypeAll(chore): Renovate commits will consistently use chore, aiding in clear and predictable commit histories.

• Lockfile Maintenance: Weekly lockfile updates ensure dependencies stay fresh without overwhelming maintainers.

• Nix-Specific Configuration: Explicitly enabling Nix support ensures Renovate correctly manages Nix Flake dependencies.

• Ignoring Problematic Dependencies: Ignoring specific dependencies (for me it was stable) avoids known Renovate issues. Renovate incorrectly attempts to update stable to version tags like v208, causing update failures such as: WARN: Error updating branch: update failure (branch="renovate/stable-208.x")

Explicitly listing these dependencies in ignoreDeps circumvents this problem. Furthermore, I only want to bump stable inputs, for example from 24.05 to 24.11 when I’m ready to upgrade my system.

If you want to do so, you can use renovate packagerules to carefully filter your updates.

Conclusion

By using Renovate with a carefully tuned configuration, you benefit from automated dependency management tailored specifically to Nix Flakes. This approach improves project maintainability, reduces manual overhead, and helps prevent dependency-related security issues.