modules: system: packages: make it configurable

modules/system/packages.nix

@@ -1,9 +1,16 @@
 # Common packages
-{ config, pkgs, ... }:
-
+{ config, lib, pkgs, ... }:
+let
+  cfg = config.my.system.packages;
+in
 {
-  # List packages installed in system profile. To search, run:
-  # $ nix search wget
+  options.my.system.packages = with lib; {
+    enable = my.mkDisableOption "packages configuration";
+
+    allowUnfree = my.mkDisableOption "allow unfree packages";
+  };
+
+  config = lib.mkIf cfg.enable {
     environment.systemPackages = with pkgs; [
       git
       git-crypt
@@ -12,12 +19,18 @@
       wget
     ];
 
-  programs.vim.defaultEditor = true; # Modal editing is life
-  programs.zsh = {
+    programs = {
+      vim.defaultEditor = true; # Modal editing is life
+
+      zsh = {
         enable = true; # Use integrations
         # Disable global compinit when a user config exists
         enableGlobalCompInit = !config.my.home.zsh.enable;
       };
+    };
 
-  nixpkgs.config.allowUnfree = true; # Because I don't care *that* much.
+    nixpkgs.config = {
+      allowUnfree = cfg.allowUnfree; # Because I don't care *that* much.
+    };
+  };
 }