{
  inputs = {
    flake-utils = {
      type = "github";
      owner = "numtide";
      repo = "flake-utils";
      ref = "main";
    };
    crane = {
      url = "github:ipetkov/crane";
      inputs.nixpkgs.follows = "nixpkgs";
    };
    nixpkgs = {
      type = "github";
      owner = "nixos";
      repo = "nixpkgs";
      ref = "nixos-unstable";
    };
  };
  outputs = { self, nixpkgs, flake-utils, crane }: let
    supportedSystems = ["aarch64-linux" "x86_64-linux"];
    forAllSystems = f: flake-utils.lib.eachSystem supportedSystems f;
  in {
    nixosModules.default = import ./configuration.nix self;
  } // forAllSystems (system: let
    pkgs = nixpkgs.legacyPackages.${system};
    crane' = crane.mkLib pkgs;

    kittybox = pkgs.callPackage ./kittybox.nix {
      # TODO: this may break cross-compilation. It may be better to
      # inject it as an overlay. However, I am unsure whether Crane
      # can recognize it's being passed a cross-compilation set.
      crane = crane';

      nixosTests = {
        smokeTest = self.checks.${system}.nixos-test;
        postgresSmokeTest = self.checks.${system}.nixos-test-postgres;
      };
    };
  in {
    packages = {
      kittybox = kittybox;
      default = self.packages.${system}.kittybox;
    };

    checks = {
      kittybox = self.packages.${system}.kittybox;

      deps = self.packages.${system}.kittybox.cargoArtifacts;
      clippy = self.packages.${system}.kittybox.clippy;

      distributed-test = pkgs.nixosTest (import ./nixos-tests/distributed-test.nix self);
      nixos-test = pkgs.nixosTest (import ./nixos-tests/smoke-test.nix self);
      nixos-test-postgres = pkgs.nixosTest (import ./nixos-tests/postgres-smoke-test.nix self);
      webmention-test = pkgs.nixosTest (import ./nixos-tests/webmention-test.nix self);

      dockerContainer = pkgs.callPackage ./docker.nix {
        inherit (self.packages.${system}) kittybox;
        rev = self.rev or "development";
        inherit (self) lastModifiedDate;
      };
    };

    devShells.default = pkgs.callPackage ./shell.nix {};
  });
}