{
  inputs = {
    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
  };
  outputs = { self, nixpkgs, ... }: let
    forAllSystems = f: (nixpkgs.lib.genAttrs [ "x86_64-linux" "aarch64-linux" ] (system: let
      pkgs = import nixpkgs { inherit system; };
    in f { inherit pkgs system; } ));
  in {
    packages = forAllSystems ({ pkgs, system, ... }: {
      nixos-exporter = pkgs.rustPlatform.buildRustPackage rec {
        pname = "nixos-exporter";
        version = "0.6.0";

        src = ./.;

        nativeBuildInputs = [
          pkgs.pkg-config
        ];

        buildInputs = [
          pkgs.openssl
        ];

        cargoLock.lockFile = ./Cargo.lock;

      };
      default = self.packages."${system}".nixos-exporter;
    });

    apps = forAllSystems ({ pkgs, system, ... }: {
      nixos-exporter = {
        type = "app";
        program = self.packages."${system}".nixos-exporter + "/bin/nixos-exporter";
      };
      nixos-validator = {
        type = "app";
        program = self.packages."${system}".nixos-exporter + "/bin/nixos-validator";
      };
      default = self.apps."${system}".nixos-exporter;
    });


    nixosModules = {
      nixos-exporter = { config, pkgs, lib, ... }:
      with lib;
      let
        cfg = config.services.nixos-exporter;
      in {
        options = {
          services.nixos-exporter = {
            enable = mkEnableOption "Export NixOS status metrics";
            listen = mkOption {
              type = with types; nullOr str;
              default = null;
              description = "Interface for metrics";
              example = "[::]:2345";
            };
          };
        };

        config = mkIf cfg.enable {
          users.users."nixos-exporter" = {
            isSystemUser = true;
            group = "nixos-exporter";
          };

          users.groups."nixos-exporter" = {};

          systemd.services."nixos-exporter" = {
            wantedBy = [ "multi-user.target" ];
            after = [ "network.target" ];
            serviceConfig = {
              Restart = "always";
              PrivateTmp = true;
              WorkingDirectory = "/tmp";
              RuntimeDirectory = "nixos-exporter";
              User = "nixos-exporter";
              Group = "nixos-exporter";
              ExecStart = ''
                ${self.packages."${config.nixpkgs.system}".nixos-exporter}/bin/nixos-exporter ${optionalString (cfg.listen != null) "--listen ${escapeShellArg cfg.listen}"}
              '';
            };
          };
        };
      };

      nixos-validator = { config, pkgs, lib, ... }:
      with lib;
      let
        cfg = config.services.nixos-validator;
      in {
        options = {
          services.nixos-validator = {
            enable = mkEnableOption "Validate NixOS metrics";
            listen = mkOption {
              type = with types; nullOr str;
              default = null;
              description = "Interface for metrics";
              example = "[::]:2345";
            };
            prometheusUrl = mkOption {
              type = types.str;
              description = "Url for Prometheus";
              example = "https://prometheus.monitoring.clerie.de";
            };
            prometheusQueryTagTemplate = mkOption {
              type = with types; nullOr str;
              default = null;
              description = "Template for Prometheus Query";
              example = "instance=\"{}\"";
            };
            hydraUrl = mkOption {
              type = types.str;
              description = "Url for Hydra";
              example = "https://hydra.clerie.de";
            };
            hydraJobTemplate = mkOption {
              type = with types; nullOr str;
              default = null;
              description = "Template for Hydra Job Url";
              example = "nixfiles/nixfiles/nixosConfigurations.{}";
            };
          };
        };

        config = mkIf cfg.enable {
          users.users."nixos-validator" = {
            isSystemUser = true;
            group = "nixos-validator";
          };

          users.groups."nixos-validator" = {};

          systemd.services."nixos-validator" = {
            wantedBy = [ "multi-user.target" ];
            after = [ "network.target" ];
            serviceConfig = {
              Restart = "always";
              PrivateTmp = true;
              WorkingDirectory = "/tmp";
              RuntimeDirectory = "nixos-validator";
              User = "nixos-validator";
              Group = "nixos-validator";
              ExecStart = ''
                ${self.packages."${config.nixpkgs.system}".nixos-exporter}/bin/nixos-validator ${concatStringsSep " " [
                  (optionalString (cfg.listen != null) "--listen ${escapeShellArg cfg.listen}")
                  "--prometheus-url ${escapeShellArg cfg.prometheusUrl}"
                  (optionalString (cfg.prometheusQueryTagTemplate != null) "--prometheus-query-tag-template ${escapeShellArg cfg.prometheusQueryTagTemplate}")
                  "--hydra-url ${escapeShellArg cfg.hydraUrl}"
                  (optionalString (cfg.hydraJobTemplate != null) "--hydra-job-template ${escapeShellArg cfg.hydraJobTemplate}")
                ]}
              '';
            };
          };
        };
      };

      default = { ... }:
      {
        imports = [
          self.nixosModules.nixos-exporter
          self.nixosModules.nixos-validator
        ];
      };
    };

    hydraJobs = {
      inherit (self)
        packages;
    };
  };
}