starlette/fastapi: fix error on host-based routing

CHANGELOG.md

@@ -16,6 +16,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - `opentelemetry-instrumentation-botocore` Use `cloud.region` instead of `aws.region` span attribute as per semantic conventions.
   ([#3474](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/3474))
 
+### Fixed
+
+- `opentelemetry-instrumentation-starlette` Fixes a crash when host-based routing is used ([#3507](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/3507/))
+- `opentelemetry-instrumentation-fastapi` Fixes a crash when host-based routing is used ([#3507](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/3507/))
 
 ## Version 1.33.0/0.54b0 (2025-05-09)
 
@@ -44,7 +48,6 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - `opentelemetry-instrumentation-botocore` Capture server attributes for botocore API calls
   ([#3448](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/3448))
 
-
 ## Version 1.32.0/0.53b0 (2025-04-10)
 
 ### Added
@@ -70,7 +73,6 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - `opentelemetry-instrumentation-aiokafka` Fix send_and_wait method no headers kwargs error.
   ([[#3332](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/3332)])
 
-
 ## Version 1.31.0/0.52b0 (2025-03-12)
 
 ### Added

instrumentation/opentelemetry-instrumentation-fastapi/src/opentelemetry/instrumentation/fastapi/__init__.py

@@ -428,7 +428,11 @@ def _get_route_details(scope):
     for starlette_route in app.routes:
         match, _ = starlette_route.matches(scope)
         if match == Match.FULL:
-            route = starlette_route.path
+            try:
+                route = starlette_route.path
+            except AttributeError:
+                # routes added via host routing won't have a path attribute
+                route = scope.get("path")
             break
         if match == Match.PARTIAL:
             route = starlette_route.path

instrumentation/opentelemetry-instrumentation-fastapi/tests/test_fastapi_instrumentation.py

@@ -207,6 +207,7 @@ async def _():
             return {"message": "ok"}
 
         app.mount("/sub", app=sub_app)
+        app.host("testserver2", sub_app)
 
         return app
 
@@ -263,6 +264,10 @@ def test_sub_app_fastapi_call(self):
             span.attributes[SpanAttributes.HTTP_URL],
         )
 
+    def test_host_fastapi_call(self):
+        client = TestClient(self._app, base_url="https://testserver2")
+        client.get("/")
+
 
 class TestBaseAutoFastAPI(TestBaseFastAPI):
     @classmethod

instrumentation/opentelemetry-instrumentation-starlette/src/opentelemetry/instrumentation/starlette/__init__.py

@@ -355,7 +355,11 @@ def _get_route_details(scope: dict[str, Any]) -> str | None:
     for starlette_route in app.routes:
         match, _ = starlette_route.matches(scope)
         if match == Match.FULL:
-            route = starlette_route.path
+            try:
+                route = starlette_route.path
+            except AttributeError:
+                # routes added via host routing won't have a path attribute
+                route = scope.get("path")
             break
         if match == Match.PARTIAL:
             route = starlette_route.path

instrumentation/opentelemetry-instrumentation-starlette/tests/test_starlette_instrumentation.py

@@ -18,7 +18,7 @@
 
 from starlette import applications
 from starlette.responses import PlainTextResponse
-from starlette.routing import Mount, Route
+from starlette.routing import Host, Mount, Route
 from starlette.testclient import TestClient
 from starlette.websockets import WebSocket
 
@@ -140,6 +140,10 @@ def test_sub_app_starlette_call(self):
                 span.attributes[SpanAttributes.HTTP_URL],
             )
 
+    def test_host_starlette_call(self):
+        client = TestClient(self._app, base_url="http://testserver2")
+        client.get("/")
+
     def test_starlette_route_attribute_added(self):
         """Ensure that starlette routes are used as the span name."""
         self._client.get("/user/123")
@@ -298,6 +302,7 @@ def sub_home(_):
                 Route("/user/{username}", home),
                 Route("/healthzz", health),
                 Mount("/sub", app=sub_app),
+                Host("testserver2", sub_app),
             ],
         )