Django trace response headers

.github/workflows/test.yml

@@ -6,7 +6,7 @@ on:
     - 'release/*'
   pull_request:
 env:
-  CORE_REPO_SHA: cad261e5dae1fe986c87e6965664b45cc9ab73c3
+  CORE_REPO_SHA: 7b11971c504387341df0c38f5a34d7d1293c7e4f
 
 jobs:
   build:

CHANGELOG.md

@@ -21,6 +21,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   ([#299](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/299))
 - `opentelemetry-instrumenation-django` now supports request and response hooks.
   ([#407](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/407))
+- Add trace response header support for Django.
+  ([#395](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/395))
 
 ### Removed
 - Remove `http.status_text` from span attributes

instrumentation/opentelemetry-instrumentation-django/src/opentelemetry/instrumentation/django/middleware.py

@@ -20,6 +20,9 @@
 
 from opentelemetry.context import attach, detach
 from opentelemetry.instrumentation.django.version import __version__
+from opentelemetry.instrumentation.propagators import (
+    get_global_back_propagator,
+)
 from opentelemetry.instrumentation.utils import extract_attributes_from_object
 from opentelemetry.instrumentation.wsgi import (
     add_response_attributes,
@@ -179,6 +182,11 @@ def process_response(self, request, response):
                 response,
             )
 
+            propagator = get_global_back_propagator()
+            if propagator:
+                propagator.inject(response)
+
+            # record any exceptions raised while processing the request
             exception = request.META.pop(self._environ_exception_key, None)
             if _DjangoMiddleware._otel_response_hook:
                 _DjangoMiddleware._otel_response_hook(  # pylint: disable=not-callable

instrumentation/opentelemetry-instrumentation-django/tests/test_middleware.py

@@ -26,10 +26,19 @@
     DjangoInstrumentor,
     _DjangoMiddleware,
 )
+from opentelemetry.instrumentation.propagators import (
+    TraceResponsePropagator,
+    set_global_back_propagator,
+)
 from opentelemetry.sdk.trace import Span
 from opentelemetry.test.test_base import TestBase
 from opentelemetry.test.wsgitestutil import WsgiTestBase
-from opentelemetry.trace import SpanKind, StatusCode
+from opentelemetry.trace import (
+    SpanKind,
+    StatusCode,
+    format_span_id,
+    format_trace_id,
+)
 from opentelemetry.util.http import get_excluded_urls, get_traced_request_attrs
 
 # pylint: disable=import-error
@@ -41,6 +50,7 @@
     route_span_name,
     traced,
     traced_template,
+    with_response_header,
 )
 
 DJANGO_2_2 = VERSION >= (2, 2)
@@ -52,6 +62,7 @@
     url(r"^excluded_arg/", excluded),
     url(r"^excluded_noarg/", excluded_noarg),
     url(r"^excluded_noarg2/", excluded_noarg2),
+    url(r"^response_header/", with_response_header),
     url(r"^span_name/([0-9]{4})/$", route_span_name),
 ]
 _django_instrumentor = DjangoInstrumentor()
@@ -309,3 +320,55 @@ def response_hook(span, request, response):
         self.assertIsInstance(response_hook_args[1], HttpRequest)
         self.assertIsInstance(response_hook_args[2], HttpResponse)
         self.assertEqual(response_hook_args[2], response)
+
+    def test_trace_response_headers(self):
+        response = Client().get("/span_name/1234/")
+        self.assertNotIn("Server-Timing", response._headers)
+        self.memory_exporter.clear()
+
+        set_global_back_propagator(TraceResponsePropagator())
+
+        response = Client().get("/span_name/1234/")
+        span = self.memory_exporter.get_finished_spans()[0]
+
+        self.assertIn("traceresponse", response._headers)
+        self.assertEqual(
+            response._headers["access-control-expose-headers"][0],
+            "Access-Control-Expose-Headers",
+        )
+        self.assertEqual(
+            response._headers["access-control-expose-headers"][1],
+            "traceresponse",
+        )
+        self.assertEqual(
+            response._headers["traceresponse"][0], "traceresponse"
+        )
+        self.assertEqual(
+            response._headers["traceresponse"][1],
+            "00-{0}-{1}-01".format(
+                format_trace_id(span.get_span_context().trace_id),
+                format_span_id(span.get_span_context().span_id),
+            ),
+        )
+        self.memory_exporter.clear()
+
+    def test_trace_response_header_pre_existing_header(self):
+        set_global_back_propagator(TraceResponsePropagator())
+
+        response = Client().get("/response_header/")
+        span = self.memory_exporter.get_finished_spans()[0]
+        self.assertIn("traceresponse", response._headers)
+        self.assertEqual(
+            response._headers["access-control-expose-headers"][1],
+            "X-Test-Header, traceresponse",
+        )
+        self.assertEqual(
+            response._headers["traceresponse"][1],
+            "abc; val=1, "
+            + "00-{0}-{1}-01".format(
+                format_trace_id(span.get_span_context().trace_id),
+                format_span_id(span.get_span_context().span_id),
+            ),
+        )
+
+        self.memory_exporter.clear()

instrumentation/opentelemetry-instrumentation-django/tests/views.py

@@ -1,5 +1,9 @@
 from django.http import HttpResponse
 
+from opentelemetry.instrumentation.propagators import (
+    _HTTP_HEADER_ACCESS_CONTROL_EXPOSE_HEADERS,
+)
+
 
 def traced(request):  # pylint: disable=unused-argument
     return HttpResponse()
@@ -29,3 +33,10 @@ def route_span_name(
     request, *args, **kwargs
 ):  # pylint: disable=unused-argument
     return HttpResponse()
+
+
+def with_response_header(request):  # pylint: disable=unused-argument
+    response = HttpResponse()
+    response["traceresponse"] = "abc; val=1"
+    response[_HTTP_HEADER_ACCESS_CONTROL_EXPOSE_HEADERS] = "X-Test-Header"
+    return response