test complete

Author: sanderegg

packages/service-library/src/servicelib/fastapi/cancellation_middleware.py

@@ -27,9 +27,22 @@ async def _handler(app: ASGIApp, scope: Scope, queue: asyncio.Queue, send: Send)
     return await app(scope, queue.get, send)
 
 
-class CancellationMiddleware:
+class RequestCancellationMiddleware:
+    """ASGI Middleware to cancel server requests in case of client disconnection.
+    Reason: FastAPI-based (e.g. starlette) servers do not automatically cancel
+    server requests in case of client disconnection. This middleware will cancel
+    the server request in case of client disconnection via asyncio.CancelledError.
+
+    WARNING: FastAPI BackgroundTasks will also get cancelled. Use with care.
+    TIP: use asyncio.Task in that case
+    """
+
     def __init__(self, app: ASGIApp) -> None:
         self.app = app
+        _logger.warning(
+            "CancellationMiddleware is in use, in case of client disconection, "
+            "FastAPI BackgroundTasks will be cancelled too!",
+        )
 
     async def __call__(self, scope: Scope, receive: Receive, send: Send) -> None:
         if scope["type"] != "http":

packages/service-library/tests/fastapi/test_cancellation_middleware.py

@@ -9,7 +9,7 @@
 import uvicorn
 from fastapi import APIRouter, BackgroundTasks, FastAPI
 from pytest_simcore.helpers.logging_tools import log_context
-from servicelib.fastapi.cancellation_middleware import CancellationMiddleware
+from servicelib.fastapi.cancellation_middleware import RequestCancellationMiddleware
 from servicelib.utils import unused_port
 from yarl import URL
 
@@ -68,7 +68,7 @@ async def sleep_with_background_task(
 def fastapi_app(fastapi_router: APIRouter) -> FastAPI:
     app = FastAPI()
     app.include_router(fastapi_router)
-    app.add_middleware(CancellationMiddleware)
+    app.add_middleware(RequestCancellationMiddleware)
     return app
 
 

services/storage/src/simcore_service_storage/core/application.py

@@ -10,6 +10,7 @@
 from fastapi.middleware.gzip import GZipMiddleware
 from fastapi_pagination import add_pagination
 from servicelib.fastapi import timing_middleware
+from servicelib.fastapi.cancellation_middleware import RequestCancellationMiddleware
 from servicelib.fastapi.client_session import setup_client_session
 from servicelib.fastapi.openapi import override_fastapi_openapi_method
 from servicelib.fastapi.profiler import ProfilerMiddleware
@@ -103,6 +104,8 @@ def create_app(settings: ApplicationSettings) -> FastAPI:
 
     app.add_middleware(GZipMiddleware)
 
+    app.add_middleware(RequestCancellationMiddleware)
+
     if settings.STORAGE_TRACING:
         initialize_tracing(app, settings.STORAGE_TRACING, APP_NAME)
     if settings.STORAGE_MONITORING_ENABLED: