Update FastAPI implementation

Author: macieyng

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

@@ -227,7 +227,7 @@ def instrument_app(
             app.add_middleware(
                 OpenTelemetryMiddleware,
                 excluded_urls=excluded_urls,
-                default_span_details=_get_route_details,
+                default_span_details=_get_default_span_details,
                 server_request_hook=server_request_hook,
                 client_request_hook=client_request_hook,
                 client_response_hook=client_response_hook,
@@ -300,7 +300,7 @@ def __init__(self, *args, **kwargs):
         self.add_middleware(
             OpenTelemetryMiddleware,
             excluded_urls=_InstrumentedFastAPI._excluded_urls,
-            default_span_details=_get_route_details,
+            default_span_details=_get_default_span_details,
             server_request_hook=_InstrumentedFastAPI._server_request_hook,
             client_request_hook=_InstrumentedFastAPI._client_request_hook,
             client_response_hook=_InstrumentedFastAPI._client_response_hook,
@@ -316,26 +316,49 @@ def __del__(self):
 
 
 def _get_route_details(scope):
-    """Callback to retrieve the fastapi route being served.
-
+    """
+    Function to retrieve Starlette route from scope.
+    
     TODO: there is currently no way to retrieve http.route from
     a starlette application from scope.
-
     See: https://github.com/encode/starlette/pull/804
+    
+    Args:
+        scope: A Starlette scope
+    Returns:
+        A string containing the route or None
     """
     app = scope["app"]
     route = None
+
     for starlette_route in app.routes:
         match, _ = starlette_route.matches(scope)
         if match == Match.FULL:
             route = starlette_route.path
             break
         if match == Match.PARTIAL:
             route = starlette_route.path
-    # method only exists for http, if websocket
-    # leave it blank.
-    span_name = route or scope.get("method", "")
+    return route
+    
+
+def _get_default_span_details(scope):
+    """
+    Callback to retrieve span name and attributes from scope.
+
+    Args:
+        scope: A Starlette scope
+    Returns:
+        A tuple of span name and attributes
+    """
+    route = _get_route_details(scope)
+    method = scope.get("method", "")
     attributes = {}
     if route:
         attributes[SpanAttributes.HTTP_ROUTE] = route
+    if method and route: # http
+        span_name = f"{method} {route}"
+    elif route: # websocket
+        span_name = route
+    else: # fallback
+        span_name = method
     return span_name, attributes

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

@@ -106,7 +106,7 @@ def test_instrument_app_with_instrument(self):
         spans = self.memory_exporter.get_finished_spans()
         self.assertEqual(len(spans), 3)
         for span in spans:
-            self.assertIn("/foobar", span.name)
+            self.assertIn("GET /foobar", span.name)
 
     def test_uninstrument_app(self):
         self._client.get("/foobar")
@@ -138,15 +138,15 @@ def test_basic_fastapi_call(self):
         spans = self.memory_exporter.get_finished_spans()
         self.assertEqual(len(spans), 3)
         for span in spans:
-            self.assertIn("/foobar", span.name)
+            self.assertIn("GET /foobar", span.name)
 
     def test_fastapi_route_attribute_added(self):
         """Ensure that fastapi routes are used as the span name."""
         self._client.get("/user/123")
         spans = self.memory_exporter.get_finished_spans()
         self.assertEqual(len(spans), 3)
         for span in spans:
-            self.assertIn("/user/{username}", span.name)
+            self.assertIn("GET /user/{username}", span.name)
         self.assertEqual(
             spans[-1].attributes[SpanAttributes.HTTP_ROUTE], "/user/{username}"
         )