Create a separate script for the hub app

README.md

@@ -61,7 +61,11 @@ The gallery application backend can be run as a standalone server app by executi
 jupyterlab-gallery
 ```
 
-When run in JupyterHub context (with `jupyterhub` package installed), the standalone app will adopt the JupyterHub modifications to the single-user server.
+To run it as a single-user server in the JupyterHub context use:
+
+```bash
+jupyterhub-gallery
+```
 
 ## Requirements
 

jupyterlab_gallery/app.py

@@ -4,19 +4,6 @@
 from .manager import GalleryManager
 
 
-try:
-    from jupyterhub.singleuser.mixins import make_singleuser_app
-except ImportError:
-
-    def make_singleuser_app(cls):
-        return cls
-
-
-class classproperty(property):
-    def __get__(self, owner_self, owner_cls):
-        return self.fget(owner_cls)
-
-
 class GalleryApp(ExtensionApp):
     name = "gallery"
 
@@ -39,22 +26,8 @@ def initialize_settings(self):
     def initialize_handlers(self):
         # setting nbapp is needed for nbgitpuller
         self.serverapp.web_app.settings["nbapp"] = self.serverapp
-
         self.log.info(f"Registered {self.name} server extension")
 
-    @classproperty
-    def serverapp_class(cls):
-        """If jupyterhub is installed, apply the jupyterhub patches,
-
-        but only do this when this property is accessed, which is when
-        the gallery is used as a standalone app.
-        """
-        if cls._server_cls is None:
-            cls._server_cls = make_singleuser_app(ServerApp)
-        return cls._server_cls
-
-    _server_cls = None
-
     @classmethod
     def make_serverapp(cls, **kwargs) -> ServerApp:
         """Instantiate the ServerApp

jupyterlab_gallery/hub.py

@@ -0,0 +1,28 @@
+from jupyterhub.singleuser.mixins import make_singleuser_app
+from jupyter_server.serverapp import ServerApp
+from .app import GalleryApp
+
+
+class classproperty(property):
+    def __get__(self, owner_self, owner_cls):
+        return self.fget(owner_cls)
+
+
+class HubGalleryApp(GalleryApp):
+    # This is in a separate file because traitlets metaclass
+    # will read from each property on start, including serverapp_class,
+    # which will have side effects for the server if run outside of juypterhub
+
+    @classproperty
+    def serverapp_class(cls):
+        """If jupyterhub is installed, apply the jupyterhub patches,
+
+        but only do this when this property is accessed, which is when
+        the gallery is used as a standalone app.
+        """
+
+        if cls._server_cls is None:
+            cls._server_cls = make_singleuser_app(ServerApp)
+        return cls._server_cls
+
+    _server_cls = None

package.json

@@ -1,6 +1,6 @@
 {
     "name": "jupyterlab-gallery",
-    "version": "0.6.1",
+    "version": "0.6.2",
     "description": "A JupyterLab gallery extension for presenting and downloading examples from remote repositories",
     "keywords": [
         "jupyter",

pyproject.toml

@@ -41,6 +41,7 @@ dev = ["ruff==0.4.4"]
 
 [project.scripts]
 jupyterlab-gallery = "jupyterlab_gallery:GalleryApp.launch_instance"
+jupyterhub-gallery = "jupyterlab_gallery.hub:HubGalleryApp.launch_instance"
 
 [tool.hatch.version]
 source = "nodejs"