Use fastapi routes for metrics (#467)

backend/bracket/models/metrics.py

@@ -8,6 +8,7 @@
 from pydantic import BaseModel
 
 from bracket.utils.http import HTTPMethod
+from bracket.utils.starlette import get_route_path
 from bracket.utils.types import EnumAutoStr
 
 if TYPE_CHECKING:
@@ -28,7 +29,7 @@ class RequestDefinition(BaseModel):
     @staticmethod
     def from_request(request: Request) -> RequestDefinition:
         return RequestDefinition(
-            url=str(request.url.path),
+            url=get_route_path(request),
             method=HTTPMethod(request.method),
         )
 

backend/bracket/utils/starlette.py

@@ -0,0 +1,31 @@
+from starlette.requests import Request
+from starlette.routing import Match, Route
+
+
+def _get_route_for_request(request: Request) -> Route | None:
+    """
+    Determine FastAPI route for a starlette Request
+
+    Based on: https://stackoverflow.com/a/76203889
+    """
+
+    route: Route | None = getattr(request.state, "__route_cached__", None)
+    if route is not None:
+        return route
+
+    for route in request.app.routes:
+        match, _ = route.matches(request.scope)
+        if match is Match.FULL:
+            request.state.__route_cached__ = route
+            return route
+
+    return None
+
+
+def get_route_path(request: Request) -> str:
+    if (route := _get_route_for_request(request)) is not None:
+        msg = f"Expected `str` for `route.path`, got: {type(route.path).__name__}"
+        assert isinstance(route.path, str), msg
+        return route.path
+
+    return f"unhandled:{request.url.path}"