nixos-mods/improvedDefaults: auto authorize root if no other user is

nix/nixos-modules/improvedDefaults/default.nix

@@ -12,6 +12,7 @@ in
   imports = [
     ./command-not-found.nix
     ./powertop-tlp.nix
+    ./sshAuthorize.nix
     ./wayland.nix
   ];
 

nix/nixos-modules/improvedDefaults/sshAuthorize.nix

@@ -0,0 +1,71 @@
+{ config
+, lib
+, pkgs
+, ...
+}:
+let
+  myOpts = config.x-banananetwork;
+  cfg = config.x-banananetwork.improvedDefaults;
+in
+{
+
+
+  options = {
+
+    x-banananetwork.improvedDefaults = {
+
+      autoSshAuthorizeRoot = lib.mkEnableOption ''
+        automatically add option{x-banananetwork.sshPublicKeys} to root’s authorized keys
+        and enable option{services.openssh.settings.PermitRootLogin}
+        if no other user has "wheel" power & SSH authorized keys defined.
+
+        Also, option{services.openssh.settings.PermitRootLogin} will be disabled
+        if this module does not require it.
+      '' // { default = true; };
+
+    };
+
+  };
+
+
+  config = lib.mkIf
+    (lib.lists.all (x: x) [
+      cfg.enable
+      cfg.autoSshAuthorizeRoot
+      config.services.openssh.enable
+    ]
+    )
+    (
+      let
+        inherit (lib.attrsets) attrValues filterAttrs;
+        inherit (lib.lists) any;
+        # variables
+        users = config.users.users;
+        wheelUsers = lib.trivial.pipe users [
+          (filterAttrs (n: v: n != "root"))
+          (filterAttrs (n: v: builtins.elem "wheel" v.extraGroups))
+        ];
+        areKeysSet = authKeysOpts: any (x: true) (authKeysOpts.keys ++ authKeysOpts.keyFiles);
+        isUserAuthed = userOpts: areKeysSet userOpts.openssh.authorizedKeys;
+        # used facts
+        isNonRootAuthed = any isUserAuthed (attrValues wheelUsers);
+        isRootAuthed = isUserAuthed users."root";
+        doRootAuth = !isNonRootAuthed;
+      in
+      {
+
+        services.openssh.settings.PermitRootLogin = if isRootAuthed then true else lib.mkDefault false;
+
+        users.users.root.openssh.authorizedKeys = lib.mkIf doRootAuth (lib.mkDefault myOpts.sshPublicKeys);
+        warnings = lib.mkIf doRootAuth [
+          ''
+            root’s authorized keys were automatically configured
+            because no other user with wheel permission has authorized keys configured
+          ''
+        ];
+
+      }
+    );
+
+
+}