{
  description = "A highly structured configuration database.";

  nixConfig.extra-experimental-features = "nix-command flakes";
  nixConfig.extra-substituters = "https://nix-dram.cachix.org https://dram.cachix.org  https://nrdxp.cachix.org https://nix-community.cachix.org";
  nixConfig.extra-trusted-public-keys = "nix-dram.cachix.org-1:CKjZ0L1ZiqH3kzYAZRt8tg8vewAx5yj8Du/+iR8Efpg= dram.cachix.org-1:baoy1SXpwYdKbqdTbfKGTKauDDeDlHhUpC+QuuILEMY= nrdxp.cachix.org-1:Fc5PSqY2Jm1TrWfm88l6cvGWwz3s93c6IOifQWnhNW4= nix-community.cachix.org-1:mB9FSh9qf2dCimDSUo8Zy7bkq5CX+/rkCWyvRCYg3Fs=";

  inputs = {
    # Track channels with commits tested and built by hydra
    nixos.url = "github:nixos/nixpkgs/nixos-22.11";
    latest.url = "github:nixos/nixpkgs/nixos-unstable";

    flake-compat.url = "github:edolstra/flake-compat";
    flake-compat.flake = false;

    digga.url = "github:pub-solar/digga/fix/bootstrap-iso";
    digga.inputs.nixpkgs.follows = "nixos";
    digga.inputs.nixlib.follows = "nixos";
    digga.inputs.home-manager.follows = "home";
    digga.inputs.deploy.follows = "deploy";
    digga.inputs.darwin.follows = "darwin";
    digga.inputs.flake-compat.follows = "flake-compat";

    home.url = "github:nix-community/home-manager/release-22.11";
    home.inputs.nixpkgs.follows = "nixos";

    darwin.url = "github:LnL7/nix-darwin";
    darwin.inputs.nixpkgs.follows = "nixos";

    deploy.url = "github:serokell/deploy-rs";
    deploy.inputs.nixpkgs.follows = "nixos";
    deploy.inputs.flake-compat.follows = "flake-compat";

    agenix.url = "github:ryantm/agenix";
    agenix.inputs.nixpkgs.follows = "nixos";
    agenix.inputs.darwin.follows = "darwin";

    nixos-hardware.url = "github:nixos/nixos-hardware";

    nixos-generators.url = "github:nix-community/nixos-generators";

    master.url = "github:nixos/nixpkgs/master";
    pub-solar.url = "github:pub-solar/nixpkgs/fix/use-latest-unstable-yubikey-agent";
    scan2paperless.url = "git+https://git.pub.solar/b12f/scan2paperless.git";
  };

  outputs = {
    self,
    digga,
    nixos,
    home,
    nixos-hardware,
    agenix,
    deploy,
    scan2paperless,
    ...
  } @ inputs:
    digga.lib.mkFlake
    {
      inherit self inputs;

      channelsConfig = {
        allowUnfree = true;
      };

      supportedSystems = ["x86_64-linux" "aarch64-linux"];

      channels = {
        nixos = {
          imports = [(digga.lib.importOverlays ./overlays)];
          overlays = [];
        };
        latest = {};
      };

      lib = import ./lib {lib = digga.lib // nixos.lib;};

      sharedOverlays = [
        (final: prev: {
          __dontExport = true;
          lib = prev.lib.extend (lfinal: lprev: {
            our = self.lib;
          });
        })
        agenix.overlays.default

        (import ./pkgs)
      ];

      nixos = {
        hostDefaults = {
          system = "x86_64-linux";
          channelName = "nixos";
          imports = [(digga.lib.importExportableModules ./modules)];
          modules = [
            {lib.our = self.lib;}
            # FIXME: upstream module causes a huge number of unnecessary
            # dependencies to be pulled in for all systems -- many of them are
            # graphical. should only be imported as needed.
            # digga.nixosModules.bootstrapIso
            digga.nixosModules.nixConfig
            home.nixosModules.home-manager
            agenix.nixosModules.age
          ];
        };

        imports = [(digga.lib.importHosts ./hosts)];
        hosts = {
          /*
          set host specific properties here
          */
          bootstrap = {
            modules = [
              digga.nixosModules.bootstrapIso
            ];
          };
          PubSolarOS = {
            tests = [
              (import ./tests/first-test.nix {
                pkgs = nixos.legacyPackages.x86_64-linux;
                lib = nixos.lib;
              })
            ];
          };
        };
        importables = rec {
          profiles =
            digga.lib.rakeLeaves ./profiles
            // {
              users = digga.lib.rakeLeaves ./users;
            };

          suites = with profiles; rec {
            base = [users.pub-solar users.root];
            iso = base ++ [base-user graphical pub-solar-iso];
            pubsolaros = [full-install base-user users.root];
            anonymous = [pubsolaros users.pub-solar];

            b12f = pubsolaros ++ [users.ben social gaming mobile];
            biolimo = b12f ++ [graphical];
            chocolatebar = b12f ++ [graphical virtualisation];

            yule = pubsolaros ++ [users.yule];
            droppie = yule ++ [];
          };
        };
      };

      home = {
        imports = [(digga.lib.importExportableModules ./users/modules)];
        modules = [];
        importables = rec {
          profiles = digga.lib.rakeLeaves ./users/profiles;
          suites = with profiles; rec {
            base = [direnv git];
          };
        };
        users = let
          default = {suites, ...}: {
            imports = suites.base;
            home.stateVersion = "21.03";
          };
        in {
          pub-solar = default;
          ben = default;
          yule = default;
        };
      };

      devshell = ./shell;

      homeConfigurations = digga.lib.mkHomeConfigurations self.nixosConfigurations;

      deploy.nodes = digga.lib.mkDeployNodes self.nixosConfigurations {
        droppie = {
          sshUser = "yule";
        };
      };
    };
}