Add Django template tag for adding sentry tracing information (#2222)

Adding sentry_trace_meta to template context so meta tags including Sentry trace information can be rendered using {{ sentry_trace_meta }} in the Django templates
---------

Co-authored-by: Ivana Kellyerova <[email protected]>

Author: antonpirker

sentry_sdk/integrations/django/templates.py

@@ -1,4 +1,5 @@
 from django.template import TemplateSyntaxError
+from django.utils.safestring import mark_safe
 from django import VERSION as DJANGO_VERSION
 
 from sentry_sdk import _functools, Hub
@@ -88,6 +89,11 @@ def render(request, template_name, context=None, *args, **kwargs):
         if hub.get_integration(DjangoIntegration) is None:
             return real_render(request, template_name, context, *args, **kwargs)
 
+        # Inject trace meta tags into template context
+        context = context or {}
+        if "sentry_trace_meta" not in context:
+            context["sentry_trace_meta"] = mark_safe(hub.trace_propagation_meta())
+
         with hub.start_span(
             op=OP.TEMPLATE_RENDER,
             description=_get_template_name_description(template_name),

tests/integrations/django/myapp/templates/trace_meta.html

@@ -0,0 +1 @@
+{{ sentry_trace_meta }}

tests/integrations/django/myapp/urls.py

@@ -55,6 +55,7 @@ def path(path, *args, **kwargs):
     path("template-exc", views.template_exc, name="template_exc"),
     path("template-test", views.template_test, name="template_test"),
     path("template-test2", views.template_test2, name="template_test2"),
+    path("template-test3", views.template_test3, name="template_test3"),
     path("postgres-select", views.postgres_select, name="postgres_select"),
     path(
         "permission-denied-exc",

tests/integrations/django/myapp/views.py

@@ -175,6 +175,15 @@ def template_test2(request, *args, **kwargs):
     )
 
 
+@csrf_exempt
+def template_test3(request, *args, **kwargs):
+    from sentry_sdk import Hub
+
+    hub = Hub.current
+    capture_message(hub.get_traceparent() + "\n" + hub.get_baggage())
+    return render(request, "trace_meta.html", {})
+
+
 @csrf_exempt
 def postgres_select(request, *args, **kwargs):
     from django.db import connections

tests/integrations/django/test_basic.py

@@ -706,6 +706,26 @@ def test_read_request(sentry_init, client, capture_events):
     assert "data" not in event["request"]
 
 
+def test_template_tracing_meta(sentry_init, client, capture_events):
+    sentry_init(integrations=[DjangoIntegration()], traces_sample_rate=1.0)
+    events = capture_events()
+
+    # The view will capture_message the sentry-trace and baggage information
+    content, _, _ = client.get(reverse("template_test3"))
+    rendered_meta = b"".join(content).decode("utf-8")
+
+    traceparent, baggage = events[0]["message"].split("\n")
+    expected_meta = (
+        '<meta name="sentry-trace" content="%s"><meta name="baggage" content="%s">\n'
+        % (
+            traceparent,
+            baggage,
+        )
+    )
+
+    assert rendered_meta == expected_meta
+
+
 @pytest.mark.parametrize("with_executing_integration", [[], [ExecutingIntegration()]])
 def test_template_exception(
     sentry_init, client, capture_events, with_executing_integration