Group shared system settings

system/shared/nix/default.nix

@@ -0,0 +1,43 @@
+{ pkgs, ... }:
+{
+
+  imports = [
+    ./cachix.nix
+    ./gc.nix
+  ];
+
+  system.autoUpgrade.enable = false;
+
+  nix = {
+    settings = {
+      # enable flakes support
+      experimental-features = [ "nix-command" "flakes" ];
+
+      # Keep the built outputs of derivations in Nix store, even if the package is no longer needed
+      # - prevents the need to rebuild/redownload if it becomes a dependency again
+      # - helps with debugging or reverting to previous state
+      keep-outputs = true;
+      # Keep the derivations themselves too. A derivation describes how to build a package.
+      # - allows inspecting the build process of a package for debugging or educational purposes
+      # - allows rebuilding a package from its exact specification without having to fetch again
+      # - ensures we can reproduce a build even if the original online source goes down/changes
+      keep-derivations = true;
+
+      # Give these users/groups additional rights when connecting to the Nix daemon
+      # like specifying extra binary caches
+      trusted-users = [ "root" "@wheel" ];
+
+      # Tell nix to use xdg base directories
+      # If you're just setting this, you will need to move the directories
+      # manually, nix won't do it for you:
+      # - mv "$HOME/.nix-defexpr" "$XDG_STATE_HOME/nix/defexpr"
+      # - mv "$HOME/.nix-profile" "$XDG_STATE_HOME/nix/profile" 
+      use-xdg-base-directories = true;
+    };
+  };
+
+  nixpkgs.config.allowUnfree = true;
+
+  # Git is needed for flakes
+  environment.systemPackages = [ pkgs.git ];
+}