Add a jupyter server extension to render desktop/

A mess of a commit, should have been several.

- Finish renaming package from jupyter_desktop to
  jupyter_desktop_server
- Revert 360f9b04c5. Looks like
  websockify gets super confused when you put shell in the middle
  of it and the process it is spawning.
- Add a server extension that renders a slightly modified copy
  of vnc_lite.html as /desktop. This will be modified more and more
  as we go forward. This also helps us remove the mapping present
  in the jupyter server proxy entry

MANIFEST.in

@@ -1 +1,3 @@
-graft jupyter_desktop/share
+graft jupyter_desktop_server/share
+graft jupyter_desktop_server/etc
+graft jupyter_desktop_server/templates

jupyter_desktop_server/__init__.py

@@ -1,17 +1,20 @@
 import os
 import shlex
 import tempfile
+from notebook.utils import url_path_join as ujoin
+from tornado.web import StaticFileHandler
+from .handlers import DesktopHandler
 
 
 HERE = os.path.dirname(os.path.abspath(__file__))
 
-def setup_desktop():
+def setup_vnc():
     # make a secure temporary directory for sockets
     # This is only readable, writeable & searchable by our uid
     sockets_dir = tempfile.mkdtemp()
     sockets_path = os.path.join(sockets_dir, 'vnc-socket')
 
-    vnc_command = ' '.join((shlex.quote(p) for p in [
+    vnc_command = [
         os.path.join(HERE, 'share/tigervnc/bin/vncserver'),
         '-verbose',
         '-xstartup', os.path.join(HERE, 'share/xstartup'),
@@ -20,7 +23,7 @@ def setup_desktop():
         '-rfbunixpath', sockets_path,
         '-fg',
         ':1',
-    ]))
+    ]
     return {
         'command': [
             'websockify', '-v',
@@ -29,10 +32,18 @@ def setup_desktop():
             '5901',
             '--unix-target', sockets_path,
             '--',
-            '/bin/sh', '-c',
-            f'cd {os.getcwd()} && {vnc_command}'
-        ],
+        ] + vnc_command,
         'port': 5901,
         'timeout': 30,
-        'mappath': {'/': '/vnc_lite.html'},
     }
+
+
+def load_jupyter_server_extension(nbapp):
+    # Set up handlers picked up via config
+    base_url = nbapp.web_app.settings['base_url']
+
+    web_path = os.path.join(HERE, 'share/web')
+    nbapp.web_app.add_handlers('.*', [
+        (ujoin(base_url, 'desktop-server/static/(.*)'), StaticFileHandler, {'path': web_path}),
+        (ujoin(base_url, 'desktop'), DesktopHandler)
+    ])

jupyter_desktop_server/etc/jupyter-desktop-server-serverextension.json

@@ -0,0 +1,7 @@
+{
+  "NotebookApp": {
+    "nbserver_extensions": {
+      "jupyter_desktop_server": true
+    }
+  }
+}

jupyter_desktop_server/handlers.py

@@ -0,0 +1,24 @@
+from notebook.base.handlers import IPythonHandler
+import jinja2
+import os
+
+
+class DesktopHandler(IPythonHandler):
+    def initialize(self):
+        super().initialize()
+        # FIXME: Is this really the best way to use jinja2 here?
+        # I can't seem to get the jinja2 env in the base handler to
+        # actually load templates from arbitrary paths ugh.
+        jinja2_env = self.settings['jinja2_env']
+        jinja2_env.loader = jinja2.ChoiceLoader([
+            jinja2_env.loader,
+            jinja2.FileSystemLoader(
+                os.path.join(os.path.dirname(__file__), 'templates')
+            )
+        ])
+
+    def get(self):
+        novnc_base_url = self.base_url + "desktop-server/static/noVNC-1.1.0/"
+        self.write(
+            self.render_template('desktop.html', novnc_base_url=novnc_base_url)
+        )