nix2workflow is a library for generating GitHub matrices from nix flake outputs.

We offer both a standard library for use in any flake, along with a flake-parts module for easier integration.

You can find an example workflow for use in your own project in ./.github/workflows/example.yaml.

A basic setup might look like this. Please see the module for all options

{self, ...}: {
  imports = [ nix2workflow.flakeModule ];

  nix2workflow = {
    # this will automatically build all standard outputs in self
    root = self;

    overrides = {
      checks.systems = [ "x86_64-linux" ];
    };
  };
}

A full example can be found in ./test/module/flake.nix

The regular library will have a more complicated setup, though it also allows using lower level functions and has no restrictions on what flake outputs are used.

{
  workflowMatrix = let
    platforms = {
      x86_64-linux = {
        os = "ubuntu-latest";
        arch = "x64";
      };

      x86_64-darwin = {
        os = "macos-latest";
        arch = "x64";
      };
    };

    inherit (nix2workflow.lib { inherit platforms; }) mkMatrix;

    jobs = lib.flatten (
      (mkMatrix {
        root = self;
        output = "packages";
      })

      (mkMatrix {
        root = self;
        output = "checks";
        systems = [ "x86_64-linux" ];
      })
    );
  in {
    include = jobs;
  };
}

You can see a full example in ./test/lib/flake.nix

When the matrix is imported, a few variables with added to the matrix context. These can allow you to customize your workflow based on what packages are building - such as enabling QEMU when building for aarch64

• nix-community/nix-github-actions
  • This is the primary inspiration for this project - and I believe also one of the first projects to attempt this, so kudos!
• nix-community/nix-eval-jobs
  • I liked the idea of using hydraJobs (and possibly others) on GitHub Actions, and thought it might be fun to make a direct translation of these attributes in pure nix