{

  description = "A very basic flake";

  inputs = {
    nixpkgs.url = "github:nixos/nixpkgs/nixos-25.05";
    authentik = {
      url = "github:nix-community/authentik-nix";
    };
    mailserver = {
      url = "git+https://gitlab.com/simple-nixos-mailserver/nixos-mailserver?ref=nixos-25.05";
      inputs = {
        nixpkgs.follows = "nixpkgs";
        nixpkgs-25_05.follows = "nixpkgs";
      };
    };
    sops = {
      url = "github:Mic92/sops-nix";
      inputs.nixpkgs.follows = "nixpkgs";
    };
    disko = {
      url = "github:nix-community/disko";
      inputs.nixpkgs.follows = "nixpkgs";
    };
  };

  outputs =
    {
      self,
      nixpkgs,
      authentik,
      mailserver,
      disko,
      sops,
    }:
    rec {
      formatter.x86_64-linux = nixpkgs.legacyPackages.x86_64-linux.nixfmt-rfc-style;
      packages.x86_64-linux =
        builtins.foldl'
          (
            result: name:
            result
            // {
              iso = nixosConfigurations.${name}.config.system.build.isoImage;
            }
          )
          { }
          ( # filter all nixos configs containing installer
            builtins.filter (item: nixpkgs.lib.hasInfix "installer" item) (
              builtins.attrNames nixosConfigurations
            )
          );

      nixosConfigurations = builtins.foldl' (
        result: input:
        result
        // {
          "${input}" = nixpkgs.lib.nixosSystem {
            system = "x86_64-linux";
            modules = [
              ./hosts/${input}
              ./hosts/${input}/hetzner-disk.nix
              ./default.nix
              disko.nixosModules.disko
              authentik.nixosModules.default
              mailserver.nixosModules.mailserver
            ];
          };

          # build iso image vor every config
          "${input}-installer" = nixpkgs.lib.nixosSystem {
            system = "x86_64-linux";
            modules = [
              ./hosts/${input}
              ./default.nix
              disko.nixosModules.disko
              authentik.nixosModules.default
              mailserver.nixosModules.mailserver
              "${nixpkgs}/nixos/modules/installer/cd-dvd/iso-image.nix"
              {
                users.users.administration.password = "test";
                users.users.root.password = "test";
              }
            ];
          };
        }
      ) { } (builtins.attrNames (builtins.readDir ./hosts));
    };

}