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Flake basics described using the module system

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Flake Parts

Core of a distributed framework for writing Nix Flakes.

flake-parts provides the options that represent standard flake attributes and establishes a way of working with system. Opinionated features are provided by an ecosystem of modules that you can import.

flake-partsitself has the goal to be a minimal mirror of the Nix flake schema. Used by itself, it is very lightweight.


Why Modules?

Flakes are configuration. The module system lets you refactor configuration into modules that can be shared.

It reduces the proliferation of custom Nix glue code, similar to what the module system has done for NixOS configurations.

Unlike NixOS, but following Flakes' spirit, flake-parts is not a monorepo with the implied goal of absorbing all of open source, but rather a single module that other repositories can build upon, while ensuring a baseline level of compatibility: the core attributes that constitute a flake.


  • Split your flake.nix into focused units, each in their own file.

  • Take care of system.

  • Allow users of your library flake to easily integrate your generated flake outputs into their flake.

  • Reuse project logic written by others

Getting Started

If your project does not have a flake yet:

nix flake init -t github:hercules-ci/flake-parts


Otherwise, add the input,

    flake-parts.url = "github:hercules-ci/flake-parts";

then slide mkFlake between your outputs function head and body,

  outputs = inputs@{ flake-parts, ... }:
    flake-parts.lib.mkFlake { inherit inputs; } {
      flake = {
        # Put your original flake attributes here.
      systems = [
        # systems for which you want to build the `perSystem` attributes
        # ...

Now you can add the remaining module attributes like in the the template.


See the template.


See the examples/ directory.

Projects using flake-parts

Options Reference

See options.