nixos/logrotate: rotate login/logout logs by default

nixos/modules/services/logging/logrotate.nix

@@ -4,6 +4,7 @@ with lib;
 
 let
   cfg = config.services.logrotate;
+  inherit (config.users) groups;
 
   pathOpts = { name, ... }:  {
     options = {
@@ -23,6 +24,8 @@ let
 
       path = mkOption {
         type = with types; either str (listOf str);
+        default = name;
+        defaultText = "attribute name";
         description = ''
           The path to log files to be rotated.
           Spaces are allowed and normal shell quoting rules apply,
@@ -160,6 +163,25 @@ in
       }
     ) cfg.paths;
 
+    services.logrotate = {
+      paths = {
+        "/var/log/btmp" = {
+          frequency = mkDefault "monthly";
+          keep = mkDefault 1;
+          extraConfig = ''
+            create 0660 root ${groups.utmp.name}
+          '';
+        };
+        "/var/log/wtmp" = {
+          frequency = mkDefault "monthly";
+          keep = mkDefault 1;
+          extraConfig = ''
+            create 0664 root ${groups.utmp.name}
+          '';
+        };
+      };
+    };
+
     systemd.services.logrotate = {
       description = "Logrotate Service";
       wantedBy = [ "multi-user.target" ];