✨ Add support for setting transaction name to path in FastAPI

sentry_sdk/integrations/asgi.py

@@ -37,6 +37,8 @@
 
 _DEFAULT_TRANSACTION_NAME = "generic ASGI request"
 
+TRANSACTION_STYLE_VALUES = ("endpoint", "url")
+
 
 def _capture_exception(hub, exc):
     # type: (Hub, Any) -> None
@@ -68,10 +70,10 @@ def _looks_like_asgi3(app):
 
 
 class SentryAsgiMiddleware:
-    __slots__ = ("app", "__call__")
+    __slots__ = ("app", "__call__", "transaction_style")
 
-    def __init__(self, app, unsafe_context_data=False):
-        # type: (Any, bool) -> None
+    def __init__(self, app, unsafe_context_data=False, transaction_style="endpoint"):
+        # type: (Any, bool, str) -> None
         """
         Instrument an ASGI application with Sentry. Provides HTTP/websocket
         data to sent events and basic handling for exceptions bubbling up
@@ -87,6 +89,12 @@ def __init__(self, app, unsafe_context_data=False):
                 "The ASGI middleware for Sentry requires Python 3.7+ "
                 "or the aiocontextvars package." + CONTEXTVARS_ERROR_MESSAGE
             )
+        if transaction_style not in TRANSACTION_STYLE_VALUES:
+            raise ValueError(
+                "Invalid value for transaction_style: %s (must be in %s)"
+                % (transaction_style, TRANSACTION_STYLE_VALUES)
+            )
+        self.transaction_style = transaction_style
         self.app = app
 
         if _looks_like_asgi3(app):
@@ -179,12 +187,21 @@ def event_processor(self, event, hint, asgi_scope):
             event.get("transaction", _DEFAULT_TRANSACTION_NAME)
             == _DEFAULT_TRANSACTION_NAME
         ):
-            endpoint = asgi_scope.get("endpoint")
-            # Webframeworks like Starlette mutate the ASGI env once routing is
-            # done, which is sometime after the request has started. If we have
-            # an endpoint, overwrite our generic transaction name.
-            if endpoint:
-                event["transaction"] = transaction_from_function(endpoint)
+            if self.transaction_style == "endpoint":
+                endpoint = asgi_scope.get("endpoint")
+                # Webframeworks like Starlette mutate the ASGI env once routing is
+                # done, which is sometime after the request has started. If we have
+                # an endpoint, overwrite our generic transaction name.
+                if endpoint:
+                    event["transaction"] = transaction_from_function(endpoint)
+            elif self.transaction_style == "url":
+                # FastAPI includes the route object in the scope to let Sentry extract the
+                # path from it for the transaction name
+                route = asgi_scope.get("route")
+                if route:
+                    path = getattr(route, "path", None)
+                    if path is not None:
+                        event["transaction"] = path
 
         event["request"] = request_info
 

tests/integrations/asgi/test_fastapi.py

@@ -0,0 +1,46 @@
+import sys
+
+import pytest
+from fastapi import FastAPI
+from fastapi.testclient import TestClient
+from sentry_sdk import capture_message
+from sentry_sdk.integrations.asgi import SentryAsgiMiddleware
+
+
+@pytest.fixture
+def app():
+    app = FastAPI()
+
+    @app.get("/users/{user_id}")
+    async def get_user(user_id: str):
+        capture_message("hi", level="error")
+        return {"user_id": user_id}
+
+    app.add_middleware(SentryAsgiMiddleware, transaction_style="url")
+
+    return app
+
+
+@pytest.mark.skipif(sys.version_info < (3, 7), reason="requires python3.7 or higher")
+def test_fastapi_transaction_style(sentry_init, app, capture_events):
+    sentry_init(send_default_pii=True)
+    events = capture_events()
+
+    client = TestClient(app)
+    response = client.get("/users/rick")
+
+    assert response.status_code == 200
+
+    (event,) = events
+    assert event["transaction"] == "/users/{user_id}"
+    assert event["request"]["env"] == {"REMOTE_ADDR": "testclient"}
+    assert event["request"]["url"].endswith("/users/rick")
+    assert event["request"]["method"] == "GET"
+
+    # Assert that state is not leaked
+    events.clear()
+    capture_message("foo")
+    (event,) = events
+
+    assert "request" not in event
+    assert "transaction" not in event

tox.ini

@@ -212,6 +212,7 @@ deps =
 
     asgi: starlette
     asgi: requests
+    asgi: fastapi
 
     sqlalchemy-1.2: sqlalchemy>=1.2,<1.3
     sqlalchemy-1.3: sqlalchemy>=1.3,<1.4