Circular Packaging framework with nix Flakes, including ROS support

Warning

still early beta: API will change, things will break, and/or are already broken

flakoboros

Goal

When one package is defined in a flake, we can by default:

• nix build: build the package (and run its tests)
• nix shell: open a shell with the package ready to be used
• nix develop: open a shell without the built package, but with everything required to build it
• nix run: execute the main program from the package

Flakoboros allows to provide the same experience with multiple packages in a flake:

• nix build: build all packages (and run their tests)
• nix shell: open a shell with all packages ready to be used
• nix develop: open a shell without any of the packages, but with everything required to build them all
• nix run: execute the main program from all the packages (eg. a python interpreter with all the python modules available)

To do so, the main API is designed around the idea that your packages are distributed in another more-or-less central repository (eg. nixpkgs or nix-ros-overlay), and you just need my-package.overrideAttrs { src = lib.cleanSource ./. } in the flake of the source.

Circular Packaging ?

That notion of re-using an existing distribution of a package inside its source.

More details in rationale.md

API overview

example for eigenpy:

{
  description = "Bindings between Numpy and Eigen using Boost.Python";

  inputs.flakoboros.url = "github:gepetto/flakoboros";

  outputs =
    inputs:
    inputs.flakoboros.lib.mkFlakoboros (
      { lib, ... }:
      {
        pyOverrideAttrs.eigenpy = {
          src = lib.cleanSource ./.;
        };
      }
    );
}

Behind the scene, this is a shallow wrapper around `flake-parts.lib.mkFlake`, which can be used directly

{
  description = "Bindings between Numpy and Eigen using Boost.Python";

  inputs = {
    flakoboros.url = "github:gepetto/flakoboros";
    flake-parts.follows = "flakoboros/flake-parts";
    systems.follows = "flakoboros/systems";
  };

  outputs =
    inputs:
    inputs.flake-parts.lib.mkFlake { inherit inputs; } (
      { lib, ... }:
      {
        systems = import inputs.systems;
        imports = [
          inputs.flakoboros.flakeModule
          {
            flakoboros.pyOverrideAttrs.eigenpy = {
              src = lib.cleanSource ./.;
            };
          }
        ];
      }
    );
}

(the full list is defined in options.nix)

This will:

• define overlays.flakoboros with this override
• (if you don't opt-out) instanciate pkgs with that overlay
• inherit this in packages.${system}.py-eigenpy
• define packages.${system}.default as a buildEnv including all others packages.${system}.* (for nix build & nix shell)
• define devShells.${system}.default as a mkShell with inputsFrom the same packages.${system}.* (for nix develop / nix-direnv)

ROS

If you have ROS packages, the default package and devShell will use a default ROS distribution (eg. rolling), but the same features are available for other distros, with eg.

• nix build .#ros-humble
• nix shell .#ros-jazzy
• nix develop .#ros-kilted
• nix run .#ros-rolling

Also, standard ROS tools like colcon and ros2cli will be included.

Extend pkgs, aka alternate universes

flakoboros = {
  extends.eigen5 = final: { eigen = final.eigen_5; };
  pyOverrideAttrs.eigenpy = {
    src = lib.cleanSource ./.;
  };
};

This will:

• define pkgs, packages.${system}.py-eigenpy and packages.${system}.default as before
• define pkgs.pkgs-eigen5 as another pkgs instance but where eigen is overriden everywhere by eigen_5
• define packages.${system}.pkgs-eigen5, equivalent to packages.${system}.default but with eigen 5
• add scoped everything else, eg. packages.${system}.pkgs-eigen5.py-eigenpy (technically packages.${system}.pkgs-eigen5.passthru.py-eigenpy)
• define devShells.${system}.pkgs-eigen5

So in your CI, you can build . and .#pkgs-eigen5 to check all your stack with both eigen 3.4.1 and 5.0.1.

Also, you can either echo 'use flake .' > .envrc or echo 'use flake .#pkgs-eigen5' > .envrc, and follow your usual cmake -B build && cmake --build build workflow.