Auto-instrument Django with WSGI middleware

ddtrace/contrib/django/patch.py

@@ -360,6 +360,10 @@ def traced_get_response(django, pin, func, instance, args, kwargs):
         log.debug("Failed to trace django request %r", args, exc_info=True)
         return func(*args, **kwargs)
     else:
+        root_span = pin.tracer.current_root_span()
+        if root_span and root_span.name == "wsgi.request":
+            root_span.resource = resource
+            root_span.service = trace_utils.int_service(pin, config.django)
         with pin.tracer.trace(
             "django.request",
             resource=resource,
@@ -553,6 +557,15 @@ def traced_as_view(django, pin, func, instance, args, kwargs):
     return wrapt.FunctionWrapper(view, traced_func(django, "django.view", resource=func_name(view)))
 
 
+@trace_utils.with_traced_module
+def traced_get_wsgi_application(django, pin, func, instance, args, kwargs):
+    from ddtrace.contrib.wsgi import DDWSGIMiddleware
+
+    config.django["distributed_tracing"] = False
+
+    return DDWSGIMiddleware(func(*args, **kwargs))
+
+
 def _patch(django):
     Pin().onto(django)
     trace_utils.wrap(django, "apps.registry.Apps.populate", traced_populate(django))
@@ -584,6 +597,10 @@ def _patch(django):
         import django.views.generic.base
     trace_utils.wrap(django, "views.generic.base.View.as_view", traced_as_view(django))
 
+    if "django.core.wsgi" not in sys.modules:
+        import django.core.wsgi
+    trace_utils.wrap(django, "core.wsgi.get_wsgi_application", traced_get_wsgi_application(django))
+
 
 def patch():
     # DEV: this import will eventually be replaced with the module given from an import hook
@@ -610,6 +627,7 @@ def _unpatch(django):
     for conn in django.db.connections.all():
         trace_utils.unwrap(conn, "cursor")
     trace_utils.unwrap(django.db.connections, "all")
+    trace_utils.unwrap(django.core.wsgi, "get_wsgi_application")
 
 
 def unpatch():

ddtrace/contrib/wsgi/__init__.py

@@ -2,6 +2,14 @@
 The Datadog WSGI middleware traces all WSGI requests.
 
 
+Enabling
+~~~~~~~~
+
+The WSGI instrumentation will be automatically added to a Django or Flask
+application when using :ref:`ddtrace-run<ddtracerun>` or
+:ref:`patch_all()<patch_all>`.
+
+
 Usage
 ~~~~~
 

releasenotes/notes/django-wsgi-e46a93f2fb7966a9.yaml

@@ -0,0 +1,4 @@
+---
+features:
+  - |
+    Auto-instrument Django get_wsgi_application.

riotfile.py

@@ -120,6 +120,9 @@ def select_pys(min_version=min(SUPPORTED_PYTHON_VERSIONS), max_version=max(SUPPO
         Venv(
             name="django",
             command="pytest {cmdargs} tests/contrib/django",
+            pkgs={
+                "WebTest": latest,
+            },
             venvs=[
                 Venv(
                     pys=select_pys(max_version=3.6),

tests/contrib/django/django1_app/settings.py

@@ -1,7 +1,7 @@
 import os
 
 ALLOWED_HOSTS = [
-    "testserver",
+    "*",
 ]
 
 BASE_DIR = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))

tests/contrib/django/django_app/settings.py

@@ -1,7 +1,7 @@
 import os
 
 ALLOWED_HOSTS = [
-    "testserver",
+    "*",
 ]
 
 BASE_DIR = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))

tests/contrib/django/test_django_snapshots.py

@@ -57,6 +57,12 @@ def test_safe_string_encoding(client):
     assert client.get("/safe-template/").status_code == 200
 
 
+@pytest.mark.django_db
+def test_404_exceptions(client):
+    assert client.get("/404-view/").status_code == 404
+
+
+@pytest.mark.django_db
 @snapshot(
     variants={
         "18x": django.VERSION < (1, 9),
@@ -65,5 +71,11 @@ def test_safe_string_encoding(client):
         "": django.VERSION >= (2, 2),
     }
 )
-def test_404_exceptions(client):
-    assert client.get("/404-view/").status_code == 404
+def test_wsgi_app():
+    from django.core.wsgi import get_wsgi_application
+    from webtest import TestApp
+
+    app = TestApp(get_wsgi_application())
+    resp = app.get("/")
+    assert resp.status == "200 OK"
+    assert resp.status_int == 200