Merge pull request #3928 from yuvipanda/auto-backport-of-pr-3919-on-2.x

Auto backport of pr 3919 on 2.x

jupyterhub/singleuser/mixins.py

@@ -182,6 +182,7 @@ page_template = """
 
 <span>
     <a href='{{hub_control_panel_url}}'
+       id='jupyterhub-control-panel-link'
        class='btn btn-default btn-sm navbar-btn pull-right'
        style='margin-right: 4px; margin-left: 2px;'>
         Control Panel
@@ -640,7 +641,8 @@ class SingleUserNotebookAppMixin(Configurable):
         if default_url:
             self.config[self.__class__.__name__].default_url = default_url
         self._log_app_versions()
-        return super().initialize(argv)
+        super().initialize(argv)
+        self.patch_templates()
 
     def start(self):
         self.log.info("Starting jupyterhub-singleuser server version %s", __version__)
@@ -711,7 +713,6 @@ class SingleUserNotebookAppMixin(Configurable):
 
         # apply X-JupyterHub-Version to *all* request handlers (even redirects)
         self.patch_default_headers()
-        self.patch_templates()
 
     def page_config_hook(self, handler, page_config):
         """JupyterLab page config hook
@@ -744,19 +745,30 @@ class SingleUserNotebookAppMixin(Configurable):
         )
         self.jinja_template_vars['hub_host'] = self.hub_host
         self.jinja_template_vars['hub_prefix'] = self.hub_prefix
-        env = self.web_app.settings['jinja2_env']
+        self.jinja_template_vars[
+            'hub_control_panel_url'
+        ] = self.hub_host + url_path_join(self.hub_prefix, 'home')
 
-        env.globals['hub_control_panel_url'] = self.hub_host + url_path_join(
+        settings = self.web_app.settings
-            self.hub_prefix, 'home'
+        # patch classic notebook jinja env
-        )
+        jinja_envs = []
+        if 'jinja2_env' in settings:
+            # default jinja env (should we do this on jupyter-server, or only notebook?)
+            jinja_envs.append(settings['jinja2_env'])
+        if 'notebook_jinja2_env' in settings:
+            # when running with jupyter-server, classic notebook (nbclassic server extension)
+            # gets its own jinja env, which needs the same patch
+            jinja_envs.append(settings['notebook_jinja2_env'])
 
-        # patch jinja env loading to modify page template
+        # patch jinja env loading to get modified template, only for base page.html
         def get_page(name):
             if name == 'page.html':
                 return page_template
 
-        orig_loader = env.loader
+        for jinja_env in jinja_envs:
-        env.loader = ChoiceLoader([FunctionLoader(get_page), orig_loader])
+            jinja_env.loader = ChoiceLoader(
+                [FunctionLoader(get_page), jinja_env.loader]
+            )
 
     def load_server_extensions(self):
         # Loading LabApp sets $JUPYTERHUB_API_TOKEN on load, which is incorrect

jupyterhub/tests/test_singleuser.py

@@ -5,9 +5,11 @@ from contextlib import contextmanager
 from subprocess import CalledProcessError
 from subprocess import check_output
 from unittest import mock
+from urllib.parse import urlencode
 from urllib.parse import urlparse
 
 import pytest
+from bs4 import BeautifulSoup
 
 import jupyterhub
 from .. import orm
@@ -16,6 +18,7 @@ from .mocking import public_url
 from .mocking import StubSingleUserSpawner
 from .utils import async_requests
 from .utils import AsyncSession
+from .utils import get_page
 
 
 @contextmanager
@@ -225,3 +228,22 @@ def test_singleuser_app_class(JUPYTERHUB_SINGLEUSER_APP):
     else:
         assert '--ServerApp.' in out
         assert '--NotebookApp.' not in out
+
+
+async def test_nbclassic_control_panel(app, user):
+    # use StubSingleUserSpawner to launch a single-user app in a thread
+    app.spawner_class = StubSingleUserSpawner
+    app.tornado_settings['spawner_class'] = StubSingleUserSpawner
+
+    # login, start the server
+    await user.spawn()
+    cookies = await app.login_user(user.name)
+    next_url = url_path_join(user.url, "tree/")
+    url = '/?' + urlencode({'next': next_url})
+    r = await get_page(url, app, cookies=cookies)
+    r.raise_for_status()
+    assert urlparse(r.url).path == urlparse(next_url).path
+    page = BeautifulSoup(r.text, "html.parser")
+    link = page.find("a", id="jupyterhub-control-panel-link")
+    assert link, f"Missing jupyterhub-control-panel-link in {page}"
+    assert link["href"] == url_path_join(app.base_url, "hub/home")