nixos/tools: continue cleanup

- remove with lib
- shuffle some things around for readability
- add separate options for each tool

nixos/modules/installer/tools/tools.nix

@@ -3,8 +3,6 @@
 
 { config, lib, pkgs, ... }:
 
-with lib;
-
 let
   makeProg = args: pkgs.substituteAll (args // {
     dir = "bin";
@@ -17,11 +15,6 @@ let
     '';
   });
 
-  inherit (pkgs) nixos-build-vms;
-
-  nixos-install = pkgs.nixos-install.override { nix = config.nix.package; };
-  nixos-rebuild = pkgs.nixos-rebuild.override { nix = config.nix.package.out; };
-
   nixos-generate-config = makeProg {
     name = "nixos-generate-config";
     src = ./nixos-generate-config.pl;
@@ -34,8 +27,6 @@ let
     manPage = ./manpages/nixos-generate-config.8;
   };
 
-  inherit (pkgs) nixos-option;
-
   nixos-version = makeProg {
     name = "nixos-version";
     src = ./nixos-version.sh;
@@ -44,69 +35,18 @@ let
     inherit (config.system) configurationRevision;
     json = builtins.toJSON ({
       nixosVersion = config.system.nixos.version;
-    } // optionalAttrs (config.system.nixos.revision != null) {
+    } // lib.optionalAttrs (config.system.nixos.revision != null) {
       nixpkgsRevision = config.system.nixos.revision;
-    } // optionalAttrs (config.system.configurationRevision != null) {
+    } // lib.optionalAttrs (config.system.configurationRevision != null) {
       configurationRevision = config.system.configurationRevision;
     });
     manPage = ./manpages/nixos-version.8;
   };
 
-  inherit (pkgs) nixos-enter;
+  nixos-install = pkgs.nixos-install.override { nix = config.nix.package; };
-in
+  nixos-rebuild = pkgs.nixos-rebuild.override { nix = config.nix.package; };
 
-{
+  defaultConfigTemplate = ''
-
-  options.system.nixos-generate-config = {
-    configuration = mkOption {
-      internal = true;
-      type = types.str;
-      description = ''
-        The NixOS module that `nixos-generate-config`
-        saves to `/etc/nixos/configuration.nix`.
-
-        This is an internal option. No backward compatibility is guaranteed.
-        Use at your own risk!
-
-        Note that this string gets spliced into a Perl script. The perl
-        variable `$bootLoaderConfig` can be used to
-        splice in the boot loader configuration.
-      '';
-    };
-
-    desktopConfiguration = mkOption {
-      internal = true;
-      type = types.listOf types.lines;
-      default = [];
-      description = ''
-        Text to preseed the desktop configuration that `nixos-generate-config`
-        saves to `/etc/nixos/configuration.nix`.
-
-        This is an internal option. No backward compatibility is guaranteed.
-        Use at your own risk!
-
-        Note that this string gets spliced into a Perl script. The perl
-        variable `$bootLoaderConfig` can be used to
-        splice in the boot loader configuration.
-      '';
-    };
-  };
-
-  options.system.disableInstallerTools = mkOption {
-    internal = true;
-    type = types.bool;
-    default = false;
-    description = ''
-      Disable nixos-rebuild, nixos-generate-config, nixos-installer
-      and other NixOS tools. This is useful to shrink embedded,
-      read-only systems which are not expected to be rebuild or
-      reconfigure themselves. Use at your own risk!
-    '';
-  };
-
-  config = lib.mkMerge [ (lib.mkIf (config.nix.enable && !config.system.disableInstallerTools) {
-
-    system.nixos-generate-config.configuration = mkDefault ''
     # Edit this configuration file to define what should be installed on
     # your system. Help is available in the configuration.nix(5) man page, on
     # https://search.nixos.org/options and in the NixOS manual (`nixos-help`).
@@ -223,26 +163,98 @@ in
 
     }
   '';
+in
+{
+  options.system.nixos-generate-config = {
+    configuration = lib.mkOption {
+      internal = true;
+      type = lib.types.str;
+      default = defaultConfigTemplate;
+      description = ''
+        The NixOS module that `nixos-generate-config`
+        saves to `/etc/nixos/configuration.nix`.
 
-    environment.systemPackages =
+        This is an internal option. No backward compatibility is guaranteed.
-      [ nixos-build-vms
+        Use at your own risk!
-        nixos-install
+
-        nixos-rebuild
+        Note that this string gets spliced into a Perl script. The perl
-        nixos-generate-config
+        variable `$bootLoaderConfig` can be used to
-        nixos-option
+        splice in the boot loader configuration.
-        nixos-version
+      '';
-        nixos-enter
+    };
+
+    desktopConfiguration = lib.mkOption {
+      internal = true;
+      type = lib.types.listOf lib.types.lines;
+      default = [];
+      description = ''
+        Text to preseed the desktop configuration that `nixos-generate-config`
+        saves to `/etc/nixos/configuration.nix`.
+
+        This is an internal option. No backward compatibility is guaranteed.
+        Use at your own risk!
+
+        Note that this string gets spliced into a Perl script. The perl
+        variable `$bootLoaderConfig` can be used to
+        splice in the boot loader configuration.
+      '';
+    };
+  };
+
+  options.system.disableInstallerTools = lib.mkOption {
+    internal = true;
+    type = lib.types.bool;
+    default = false;
+    description = ''
+      Disable nixos-rebuild, nixos-generate-config, nixos-installer
+      and other NixOS tools. This is useful to shrink embedded,
+      read-only systems which are not expected to be rebuild or
+      reconfigure themselves. Use at your own risk!
+    '';
+  };
+
+  imports = let
+    mkToolModule = { name, package ? pkgs.${name} }: { config, ... }: {
+      options.system.tools.${name}.enable = lib.mkEnableOption "${name} script" // {
+        default = true;
+        internal = true;
+      };
+
+      config = lib.mkIf config.system.tools.${name}.enable {
+        environment.systemPackages = [ package ];
+      };
+    };
+  in [
+    (mkToolModule { name = "nixos-build-vms"; })
+    (mkToolModule { name = "nixos-enter"; })
+    (mkToolModule { name = "nixos-generate-config"; package = nixos-generate-config; })
+    (mkToolModule { name = "nixos-install"; package = nixos-install; })
+    (mkToolModule { name = "nixos-option"; })
+    (mkToolModule { name = "nixos-rebuild"; package = nixos-rebuild; })
+    (mkToolModule { name = "nixos-version"; package = nixos-version; })
   ];
 
+  config = lib.mkMerge [
+    (lib.mkIf config.system.disableInstallerTools {
+      system.tools = {
+        nixos-build-vms.enable = false;
+        nixos-enter.enable = false;
+        nixos-generate-config.enable = false;
+        nixos-install.enable = false;
+        nixos-option.enable = false;
+        nixos-rebuild.enable = false;
+        nixos-version.enable = false;
+      };
+    })
+    {
       documentation.man.man-db.skipPackages = [ nixos-version ];
 
-  })
-
       # These may be used in auxiliary scripts (ie not part of toplevel), so they are defined unconditionally.
-  ({
       system.build = {
-      inherit nixos-install nixos-generate-config nixos-option nixos-rebuild nixos-enter;
+        inherit nixos-generate-config nixos-install nixos-rebuild;
+        nixos-option = lib.warn "Accessing nixos-option through `config.system.build` is deprecated, use `pkgs.nixos-option` instead." pkgs.nixos-option;
+        nixos-enter = lib.warn "Accessing nixos-enter through `config.system.build` is deprecated, use `pkgs.nixos-enter` instead." pkgs.nixos-enter;
       };
-  })];
+    }
-
+  ];
 }