Do not mark Django HTTP 404 response spans as errors (#294)

Author: Andrey Slotin

instana/instrumentation/django/middleware.py

@@ -59,7 +59,6 @@ def process_response(self, request, response):
                 request.iscope.span.set_tag(ext.HTTP_STATUS_CODE, response.status_code)
                 tracer.inject(request.iscope.span.context, ot.Format.HTTP_HEADERS, response)
                 response['Server-Timing'] = "intid;desc=%s" % request.iscope.span.context.trace_id
-
         except Exception:
             logger.debug("Instana middleware @ process_response", exc_info=True)
         finally:
@@ -69,6 +68,11 @@ def process_response(self, request, response):
             return response
 
     def process_exception(self, request, exception):
+        from django.http.response import Http404
+
+        if isinstance(exception, Http404):
+            return None
+
         if request.iscope is not None:
             request.iscope.span.log_exception(exception)
 

tests/apps/app_django.py

@@ -7,7 +7,7 @@
 import opentracing.ext.tags as ext
 
 from django.conf.urls import url
-from django.http import HttpResponse
+from django.http import HttpResponse, Http404
 
 filepath, extension = os.path.splitext(__file__)
 os.environ['DJANGO_SETTINGS_MODULE'] = os.path.basename(filepath)
@@ -91,6 +91,10 @@ def another(request):
     return HttpResponse('Stan wuz here!')
 
 
+def not_found(request):
+    raise Http404('Nothing here')
+
+
 def complex(request):
     with opentracing.tracer.start_active_span('asteroid') as pscope:
         pscope.span.set_tag(ext.COMPONENT, "Python simple example app")
@@ -118,5 +122,6 @@ def complex(request):
     url(r'^$', index, name='index'),
     url(r'^cause_error$', cause_error, name='cause_error'),
     url(r'^another$', another),
+    url(r'^not_found$', not_found, name='not_found'),
     url(r'^complex$', complex, name='complex')
 ]

tests/frameworks/test_django.py

@@ -77,7 +77,7 @@ def test_synthetic_request(self):
         headers = {
             'X-Instana-Synthetic': '1'
         }
-        
+
         with tracer.start_active_span('test'):
             response = self.http.request('GET', self.live_server_url + '/', headers=headers)
 
@@ -155,6 +155,28 @@ def test_request_with_error(self):
         self.assertEqual('This is a fake error: /cause-error', django_span.data["http"]["error"])
         self.assertIsNone(django_span.stack)
 
+    def test_request_with_not_found(self):
+        with tracer.start_active_span('test'):
+            response = self.http.request('GET', self.live_server_url + '/not_found')
+
+        assert response
+        self.assertEqual(404, response.status)
+
+        spans = self.recorder.queued_spans()
+        spans = drop_log_spans_from_list(spans)
+
+        span_count = len(spans)
+        if span_count != 3:
+            msg = "Expected 3 spans but got %d" % span_count
+            fail_with_message_and_span_dump(msg, spans)
+
+        filter = lambda span: span.n == 'django'
+        django_span = get_first_span_by_filter(spans, filter)
+        assert(django_span)
+
+        self.assertIsNone(django_span.ec)
+        self.assertEqual(404, django_span.data["http"]["status"])
+
     def test_complex_request(self):
         with tracer.start_active_span('test'):
             response = self.http.request('GET', self.live_server_url + '/complex')