Merge pull request #489 from instana/django-header-capture

Django: capture responseHeadersOnEntrySpans

Author: GSVarsha

instana/instrumentation/django/middleware.py

@@ -29,19 +29,29 @@ def __init__(self, get_response=None):
         super(InstanaMiddleware, self).__init__(get_response)
         self.get_response = get_response
 
+    def _extract_custom_headers(self, span, headers, format):
+        if agent.options.extra_http_headers is None:
+            return
+
+        try:            
+            for custom_header in agent.options.extra_http_headers:
+                # Headers are available in this format: HTTP_X_CAPTURE_THIS
+                django_header = ('HTTP_' + custom_header.upper()).replace('-', '_') if format else custom_header
+
+                if django_header in headers:
+                    span.set_tag("http.header.%s" % custom_header, headers[django_header])
+
+        except Exception:
+            logger.debug("extract_custom_headers: ", exc_info=True)
+
     def process_request(self, request):
         try:
             env = request.environ
 
             ctx = tracer.extract(ot.Format.HTTP_HEADERS, env)
             request.iscope = tracer.start_active_span('django', child_of=ctx)
 
-            if agent.options.extra_http_headers is not None:
-                for custom_header in agent.options.extra_http_headers:
-                    # Headers are available in this format: HTTP_X_CAPTURE_THIS
-                    django_header = ('HTTP_' + custom_header.upper()).replace('-', '_')
-                    if django_header in env:
-                        request.iscope.span.set_tag("http.header.%s" % custom_header, env[django_header])
+            self._extract_custom_headers(request.iscope.span, env, format=True)
 
             request.iscope.span.set_tag(ext.HTTP_METHOD, request.method)
             if 'PATH_INFO' in env:
@@ -75,7 +85,9 @@ def process_response(self, request, response):
                         path_tpl = None
                 if path_tpl:
                     request.iscope.span.set_tag("http.path_tpl", path_tpl)
+
                 request.iscope.span.set_tag(ext.HTTP_STATUS_CODE, response.status_code)
+                self._extract_custom_headers(request.iscope.span, response.headers, format=False)
                 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:

tests/apps/app_django.py

@@ -125,10 +125,19 @@ def complex(request):
     return HttpResponse('Stan wuz here!')
 
 
+def response_with_headers(request):
+    headers = {
+        'X-Capture-This-Too': 'this too',
+        'X-Capture-That-Too': 'that too'
+    }
+    return HttpResponse('Stan wuz here with headers!', headers=headers)
+
+
 urlpatterns = [
     re_path(r'^$', index, name='index'),
     re_path(r'^cause_error$', cause_error, name='cause_error'),
     re_path(r'^another$', another),
     re_path(r'^not_found$', not_found, name='not_found'),
-    re_path(r'^complex$', complex, name='complex')
+    re_path(r'^complex$', complex, name='complex'),
+    re_path(r'^response_with_headers$', response_with_headers, name='response_with_headers')
 ]