Put the temp page under a flag

bootstrap/bootstrap.py

@@ -115,13 +115,13 @@ def serve_forever(server):
         pass
 
 def main():
+    if "--temporary-page" in sys.argv:
         # Serve the loading page until TLJH builds
         index_url="https://raw.githubusercontent.com/GeorgianaElena/the-littlest-jupyterhub/in-progress-page/bootstrap/index.html"
         favicon_url="https://raw.githubusercontent.com/jupyterhub/jupyterhub/master/share/jupyterhub/static/favicon.ico"
         urllib.request.urlretrieve(index_url, "index.html")
         urllib.request.urlretrieve(favicon_url, "favicon.ico")
 
-
         # If the bootstrap is run to upgrade TLJH, then this will raise an "Address already in use" error
         try:
             loading_page_server = HTTPServer(("", 80), LoaderPageRequestHandler)

tljh/installer.py

@@ -486,6 +486,12 @@ def main():
         nargs='*',
         help='Plugin pip-specs to install'
     )
+    argparser.add_argument(
+        '--temporary-page',
+        action='store_true',
+        default=False,
+        help='Serve a temporary page while TLJH is building'
+    )
 
     args = argparser.parse_args()
 
@@ -502,15 +508,17 @@ def main():
     ensure_jupyterlab_extensions()
 
     # Stop the http server with the loading page before traefik starts
+    if args.temporary_page:
+        pidfile = "/loading.pid"
         try:
             with open(pidfile, "r") as f:
                 pid = f.read()
             os.kill(int(pid), signal.SIGINT)
             # Remove the pid file and the temporary html page
-        os.remove('/loading.pid')
+            os.remove(pidfile)
             os.remove('/index.html')
             os.remove('/favicon.ico')
-    except:
+        except Exception as e:
             pass
 
     ensure_jupyterhub_service(HUB_ENV_PREFIX)