NixOS modules: Difference between revisions

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+==== Passing custom values to modules ====
+The [[NixOS:config_argument|<code>config</code>]], <code>options</code>, <code>lib</code>, <code>pkgs</code>, and <code>modulesPath</code> arguments are passed automatically to modules, when the module is imported.
+For example, in the following Nix flake, the `./configuration.nix` file will be provided with the default set of arguments listed above, plus `extraArg`, which was set in the `specialArgs` argument to the `nixosGenerate` function.<syntaxhighlight lang="nix">
+{
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-23.11";
+    nixos-generators = {
+      url = "github:nix-community/nixos-generators";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
+    xc = {
+      url = "github:joerdav/xc";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
+  };
+  outputs = { nixpkgs, nixos-generators, xc, ... }:
+    let
+      pkgsForSystem = system: import nixpkgs {
+        inherit system;
+        overlays = [
+          (final: prev: { xc = xc.packages.${system}.xc; })
+        ];
+      };
+      allVMs = [ "x86_64-linux" "aarch64-linux" ];
+      forAllVMs = f: nixpkgs.lib.genAttrs allVMs (system: f {
+        inherit system;
+        pkgs = pkgsForSystem system;
+      });
+    in
+    {
+      packages = forAllVMs ({ system, pkgs }: {
+        vm = nixos-generators.nixosGenerate {
+          system = system;
+          specialArgs = {
+            extraArg = "foobar";
+          };
+          modules = [
+            ./configuration.nix
+          ];
+          format = "raw";
+        };
+      });
+    };
+}
+</syntaxhighlight>
 ==== modulesPath ====