add shared update-diff (#539)

darwin/common/default.nix

@@ -4,6 +4,7 @@
     ./flake.nix
     ./nix.nix
     ./openssh.nix
+    ./update-diff.nix
   ];
 
   # It's the default login shell, and if not enabled, a lot of important configuration is not applied correctly

darwin/common/update-diff.nix

@@ -0,0 +1,12 @@
+{ config, lib, ... }:
+{
+  imports = [
+    ../../shared/common/update-diff.nix
+  ];
+
+  config = lib.mkIf config.srvos.update-diff.enable {
+    system.activationScripts.preActivation = {
+      inherit (config.srvos.update-diff) text;
+    };
+  };
+}

nixos/common/default.nix

@@ -10,7 +10,7 @@
     ./openssh.nix
     ./serial.nix
     ./sudo.nix
-    ./upgrade-diff.nix
+    ./update-diff.nix
     ./well-known-hosts.nix
     ./zfs.nix
   ];

nixos/common/update-diff.nix

@@ -0,0 +1,13 @@
+{ config, lib, ... }:
+{
+  imports = [
+    ../../shared/common/update-diff.nix
+  ];
+
+  config = lib.mkIf config.srvos.update-diff.enable {
+    system.activationScripts.update-diff = {
+      supportsDryActivation = true;
+      inherit (config.srvos.update-diff) text;
+    };
+  };
+}

nixos/common/upgrade-diff.nix → shared/common/update-diff.nix

@@ -7,13 +7,15 @@
 }:
 {
   options.srvos.update-diff = {
-    enable = lib.mkEnableOption "show package diff when updating nixos" // {
+    enable = lib.mkEnableOption "show package diff when updating" // {
       default = true;
     };
+    text = lib.mkOption {
+      type = lib.types.str;
+    };
   };
-  config = lib.mkIf config.srvos.update-diff.enable {
-    system.activationScripts.update-diff = {
-      supportsDryActivation = true;
+  config = {
+    srvos.update-diff = {
       text = ''
         if [[ -e /run/current-system ]]; then
           echo "--- diff to current-system"