{
  description = "Testing mastodon configurations";

  inputs = {
    nixpkgs.url = "github:radvendii/nixpkgs/nixos_rebuild_tests";
    disko.url = "github:nix-community/disko";
  };

  outputs = { self, nixpkgs, disko, ... }:
  let
    system = "x86_64-linux";
    pkgs = nixpkgs.legacyPackages.${system};
  in {

    nixosModules = {

      ## Fediversity modules
      fediversity = import ./fediversity;

      ## VM-specific modules
      inherit (disko.nixosModules) disko;
      disk-layout = import ./vm/disk-layout.nix;
      interactive-vm = import ./vm/interactive-vm.nix;
      mastodon-vm = import ./vm/mastodon-vm.nix;
      peertube-vm = import ./vm/peertube-vm.nix;
      pixelfed-vm = import ./vm/pixelfed-vm.nix;
    };

    nixosConfigurations = {
      mastodon = nixpkgs.lib.nixosSystem {
        inherit system;
        modules = with self.nixosModules; [
          disko
          disk-layout
          fediversity
          interactive-vm
          mastodon-vm
        ];
      };

      peertube = nixpkgs.lib.nixosSystem {
        inherit system;
        modules = with self.nixosModules; [
          disko
          disk-layout
          fediversity
          interactive-vm
          peertube-vm
        ];
      };

      pixelfed = nixpkgs.lib.nixosSystem {
        inherit system;
        modules = with self.nixosModules; [
          disko
          disk-layout
          fediversity
          interactive-vm
          pixelfed-vm
        ];
      };

      all = nixpkgs.lib.nixosSystem {
        inherit system;
        modules = with self.nixosModules; [
          disko
          disk-layout
          fediversity
          interactive-vm
          peertube-vm
          pixelfed-vm
          mastodon-vm
        ];
      };
    };

    # build with
    #     nix build .#installers.<config>
    installers =
      let
        installer = (import ./installer.nix) nixpkgs;
      in
      nixpkgs.lib.mapAttrs (_: config: installer config) self.nixosConfigurations;

    # run with
    #     nix run .#deploy.<machine>
    deploy =
      let
        deployCommand = (pkgs.callPackage ./deploy.nix {});
      in
      nixpkgs.lib.mapAttrs (name: config: deployCommand name config) self.nixosConfigurations;

    checks.${system} = {
      mastodon-garage = import ./tests/mastodon-garage.nix { inherit pkgs; };
      pixelfed-garage = import ./tests/pixelfed-garage.nix { inherit pkgs; };
    };

    devShells.${system}.default = pkgs.mkShell {
      packages = with pkgs; [
        nil
      ];
    };
  };
}