1 files changed, 27 insertions, 0 deletions
diff --git a/modules/nixos/traits/nvd-diff.nix b/modules/nixos/traits/nvd-diff.nix
new file mode 100644
index 0000000..4c59287
--- /dev/null
+++ b/modules/nixos/traits/nvd-diff.nix
@@ -0,0 +1,27 @@
+{
+  config,
+  lib,
+  pkgs,
+  ...
+}:
+let
+  cfg = config.traits.nvd-diff;
+in
+{
+  options.traits.nvd-diff = {
+    enable = lib.mkEnableOption "showing configuration diffs with NVD on upgrade" // {
+      default = true;
+    };
+  };
+
+  config = lib.mkIf cfg.enable {
+    system.activationScripts."upgrade-diff" = {
+      supportsDryActivation = true;
+      text = ''
+        ${lib.getExe pkgs.nvd} \
+          --nix-bin-dir=${config.nix.package}/bin \
+          diff /run/current-system "$systemConfig"
+      '';
+    };
+  };
+}