flake: rewrite and simplify .#listNixosOptions

common/modules/network-boot/default.nix

@@ -44,6 +44,7 @@ in
       interfaces = lib.mkOption {
         type = lib.types.listOf (lib.types.attrsOf lib.types.str);
         description = "Network interface configurations";
+        default = [ ];
         example = [
           {
             interface = "enp4s0";
@@ -58,7 +59,7 @@ in
       };
 
       username = lib.mkOption {
-        type = lib.types.str;
+        type = lib.types.nullOr lib.types.str;
         description = "Username that is the owner of all files in the tftproot directory";
         example = "myuser";
         default = null;

flake.nix

@@ -169,6 +169,7 @@
           # overlays, I drop the "pkgs" parameter of the perSystem function
           # and initialize it manually.
           pkgs = initNixpkgs inputs.nixpkgs system (builtins.attrValues self.overlays);
+          pkgsUnstable = initNixpkgs inputs.nixpkgs-unstable system (builtins.attrValues self.overlays);
 
           commonNix = {
             # All unit and integration tests as combined derivation.
@@ -219,14 +220,21 @@
 
           formatter = pkgs.nixfmt-rfc-style;
 
-          # Everything under packages can also be run. So I don't quite get
-          # the difference. So, I do not provide the `apps` key for now.
+          # Exported (and runnable) packages.
           #
-          # $ nix build .\#packages.x86_64-linux.<attribute-name>
-          # $ nix run .\#<attribute-name>
-          packages = commonNix.packages // {
-            listNixosOptions = pkgs.callPackage ./utils/list-nixos-options.nix inputs;
-          };
+          # $ nix build|run .\#packages.x86_64-linux.<attribute-name>
+          # $ nix build|run .\#<attribute-name>
+          packages =
+            let
+              listNixosOptions = pkgs.callPackage ./utils/list-nixos-options.nix {
+                inherit (inputs) self;
+                inherit (pkgsUnstable) nixos-option;
+              };
+            in
+            commonNix.packages
+            // {
+              inherit listNixosOptions;
+            };
         };
     };
 }

utils/list-nixos-options.nix

@@ -1,46 +1,17 @@
 # Lists all NixOS options of the common NixOS modules.
 
 {
-  home-manager,
-  nixpkgs,
   self,
 
   ansi,
   lib,
   nixos-option,
   writeShellScriptBin,
-  writeText,
   ...
 }:
 
 let
-  selfModules = builtins.attrValues self.nixosModules;
-  # This add structure is caused by flake-parts.
-  extractModulePath =
-    module: builtins.head (builtins.head (builtins.head module.imports).imports).imports;
-  toModuleImportLine = module: "(import ${extractModulePath module})";
-  combinedConfig = writeText "combined-config" ''
-    {
-      imports = [
-        # Pre-reququisites
-        (import ${home-manager}/nixos)
-        ${builtins.concatStringsSep "\n" (map toModuleImportLine selfModules)}
-      ];
-
-      # Activate all default options
-      phip1611.bootitems.enable = true;
-      phip1611.common.system.enable = true;
-      phip1611.common.user-env.enable = true;
-      phip1611.network-boot.enable = true;
-
-      # Remove some used but not defined errors.
-      phip1611.common.user-env.username = "foobar123";
-      phip1611.common.user-env.git.email = "phip1611n@gmail.com";
-      phip1611.common.user-env.git.username = "Philipp Schuster";
-      phip1611.network-boot.username = "foobar123";
-      phip1611.network-boot.interfaces = [];
-    }
-  '';
+  DEFAULT_HOST = "homepc";
 in
 writeShellScriptBin "list-common-nixos-options" ''
   export PATH="${
@@ -49,11 +20,9 @@ writeShellScriptBin "list-common-nixos-options" ''
       nixos-option
     ]
   }:$PATH"
-  export NIX_PATH="nixpkgs=${nixpkgs}"
-  export NIXOS_CONFIG=${combinedConfig}
 
   echo -ne "$(ansi bold)Printing all configuration options of the phip1611 common module$(ansi reset) "
   echo -e "$(ansi bold)with their default value:$(ansi reset)"
 
-  nixos-option phip1611 -r
+  nixos-option --flake ${self}#${DEFAULT_HOST} phip1611 -r
 ''