learn-flakes-the-fun-way/flake.nix

{
  inputs.nixpkgs.url = "nixpkgs/nixos-24.05";
  outputs = {
    self,
    nixpkgs,
    ...
  }: let
    systems = ["aarch64-linux" "aarch64-darwin" "x86_64-darwin" "x86_64-linux"];
    pkgsFor = func: (nixpkgs.lib.genAttrs systems (system: (func (import nixpkgs {inherit system;}))));
  in {
    packages = pkgsFor (pkgs: {
      default = pkgs.callPackage ./what-is-my-ip.nix {};
      container = pkgs.dockerTools.buildImage {
        name = "what-is-my-ip-container";
        config = {
          Cmd = ["${self.outputs.packages.${pkgs.system}.default}/bin/what-is-my-ip"];
        };
      };
    });

    devShells = pkgsFor (pkgs: {
      default = pkgs.mkShell {
        packages = [self.outputs.packages.${pkgs.system}.default];
        shellHook = ''
          echo "Hello, Nix!"
        '';
      };
    });

    nixosConfigurations = let
      system = "x86_64-linux";
    in {
      default = nixpkgs.lib.nixosSystem {
        inherit system;
        modules = [
          {
            users.users.alice = {
              isNormalUser = true;
              # enable sudo
              extraGroups = ["wheel"];
              packages = [
                self.outputs.packages.${system}.default
              ];
              initialPassword = "swordfish";
            };
            system.stateVersion = "24.05";
          }
        ];
      };
    };
  };
}