appenligth: make it optional if library is not installed

rhodecode/lib/middleware/appenlight.py

@@ -25,18 +25,10 b' import logging'
 
 log = logging.getLogger(__name__)
 
-appenlight_installed = False
-
-try:
-    from appenlight_client import make_appenlight_middleware
-    from appenlight_client.exceptions import get_current_traceback
-    from appenlight_client.wsgi import AppenlightWSGIWrapper
-    appenlight_installed = True
-except ImportError:
-    log.info('Appenlight packages not present, skipping appenlight setup')
-
 
 def track_exception(environ):
+    from appenlight_client.exceptions import get_current_traceback
+
     if 'appenlight.client' not in environ:
         return
 
@@ -44,7 +36,8 b' def track_exception(environ):'
     environ['appenlight.__traceback'] = get_current_traceback(
         skip=1,
         show_hidden_frames=True,
-        ignore_system_exceptions=True)
+        ignore_system_exceptions=True
+    )
 
 
 def track_extra_information(environ, section, value):
@@ -72,13 +65,21 b' def wrap_in_appenlight_if_enabled(app, s'
        This is in use to support our setup of the vcs related middlewares.
 
     """
-    if appenlight_installed and settings['appenlight']:
+    if settings['appenlight']:
+        try:
+            from appenlight_client import make_appenlight_middleware
+            from appenlight_client.wsgi import AppenlightWSGIWrapper
+        except ImportError:
+            log.info('Appenlight packages not present, skipping appenlight setup')
+            return app, appenlight_client
+
         app = RemoteTracebackTracker(app)
         if not appenlight_client:
             app = make_appenlight_middleware(app, settings)
             appenlight_client = app.appenlight_client
         else:
             app = AppenlightWSGIWrapper(app, appenlight_client)
+
     return app, appenlight_client