fix(virtualisation): add & extend sub{u,g}id ranges

virtualisation/containers.nix

@@ -7,4 +7,27 @@ _:
     # Create unique User Namespace for the container
     containers.userns = "auto";
   };
+  virtualisation.containers.storage.settings = {
+    # defaults
+    storage = {
+      driver = "overlay";
+      graphroot = "/var/lib/containers/storage";
+      runroot = "/run/containers/storage";
+    };
+
+    # SUB_UID_MAX: https://man7.org/linux/man-pages/man5/login.defs.5.html
+    storage.options.auto-userns-max-size = 600100000;
+  };
+
+  # Increase sub{u,g}id range
+  users.users."root" = {
+    subUidRanges = [{
+      startUid = 60100000;
+      count = 60000000;
+    }];
+    subGidRanges = [{
+      startGid = 60100000;
+      count = 60000000;
+    }];
+  };
 }