{
  description = "NixOS server base system configuration";

  inputs = {
    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";

    home-manager = {
      url = "github:nix-community/home-manager";
      inputs.nixpkgs.follows = "nixpkgs";
    };
    agenix.url = "github:ryantm/agenix";

    disko = {
      url = "github:nix-community/disko";
      inputs.nixpkgs.follows = "nixpkgs";
    };
  };
  outputs = {
    self,
    nixpkgs,
    home-manager,
    agenix,
    disko,
  } @ inputs: let
    system = "x86_64-linux";

    # hostnames
    # hosts = ["s1901" "s1902" "s1903" "s1904" "s1905" "s1906" ]; 
    hosts = ["s1901"]; 

    baseModule = {lib, ...}: {
      imports = [
        home-manager.nixosModules.default
        agenix.nixosModules.default
        disko.nixosModules.disko
      ];
      system.configurationRevision = lib.mkIf (self ? rev) self.rev;
      environment.systemPackages = [
        agenix.packages.${system}.default
      ];
    };

    mkHost = name: {
      name = name;
      value = nixpkgs.lib.nixosSystem {
        modules = [
          baseModule
          ./hosts/${name}/configuration.nix
        ];
      };
    };
  in {
    nixosConfigurations = builtins.listToAttrs (map mkHost hosts);
  };
}