Nix Integration

December 3, 2025 ยท View on GitHub

Mudyla integrates deeply with Nix to provide reproducible execution environments.

How it Works

By default, Mudyla executes Bash actions using nix develop.

  1. Flake Detection: It looks for flake.nix in the project root.
  2. Command construction: 
    nix develop --ignore-environment \
  --keep PASSTHROUGH_VAR \
  --command bash rendered_script.sh
  3. Isolation: --ignore-environment ensures the action runs in a clean environment, inheriting only what is explicitly allowed via passthrough or vars.

Running Without Nix

You can disable Nix integration using --without-nix. This is useful for:

  • Windows (automatically enabled on Windows).
  • Environments without Nix installed (e.g., some Docker containers).
  • Quick local testing when full Nix isolation is not needed.

When disabled, Mudyla uses the system bash (or Git Bash on Windows) and inherits the full parent environment.

Forcing Nix Integration

Even if Mudyla detects an environment where Nix is typically disabled (like Windows), you can force Nix integration using the --force-nix flag. This requires a working Nix installation and is primarily useful for development or debugging Nix-related issues on platforms where it's usually skipped.