ASGI lifespan failure on exception (#2627)

sanic/asgi.py

@@ -9,7 +9,7 @@ from sanic.compat import Header
 from sanic.exceptions import ServerError
 from sanic.helpers import Default
 from sanic.http import Stage
-from sanic.log import logger
+from sanic.log import error_logger, logger
 from sanic.models.asgi import ASGIReceive, ASGIScope, ASGISend, MockTransport
 from sanic.request import Request
 from sanic.response import BaseHTTPResponse
@@ -85,13 +85,27 @@ class Lifespan:
     ) -> None:
         message = await receive()
         if message["type"] == "lifespan.startup":
-            await self.startup()
-            await send({"type": "lifespan.startup.complete"})
+            try:
+                await self.startup()
+            except Exception as e:
+                error_logger.exception(e)
+                await send(
+                    {"type": "lifespan.startup.failed", "message": str(e)}
+                )
+            else:
+                await send({"type": "lifespan.startup.complete"})
 
         message = await receive()
         if message["type"] == "lifespan.shutdown":
-            await self.shutdown()
-            await send({"type": "lifespan.shutdown.complete"})
+            try:
+                await self.shutdown()
+            except Exception as e:
+                error_logger.exception(e)
+                await send(
+                    {"type": "lifespan.shutdown.failed", "message": str(e)}
+                )
+            else:
+                await send({"type": "lifespan.shutdown.complete"})
 
 
 class ASGIApp:

tests/test_asgi.py

@@ -8,7 +8,7 @@ import uvicorn
 
 from sanic import Sanic
 from sanic.application.state import Mode
-from sanic.asgi import MockTransport
+from sanic.asgi import ASGIApp, MockTransport
 from sanic.exceptions import BadRequest, Forbidden, ServiceUnavailable
 from sanic.request import Request
 from sanic.response import json, text
@@ -16,6 +16,12 @@ from sanic.server.websockets.connection import WebSocketConnection
 from sanic.signals import RESERVED_NAMESPACES
 
 
+try:
+    from unittest.mock import AsyncMock
+except ImportError:
+    from tests.asyncmock import AsyncMock  # type: ignore
+
+
 @pytest.fixture
 def message_stack():
     return deque()
@@ -558,3 +564,39 @@ async def test_asgi_serve_location(app):
 
     _, response = await app.asgi_client.get("/")
     assert response.text == "http://<ASGI>"
+
+
+@pytest.mark.asyncio
+async def test_error_on_lifespan_exception_start(app, caplog):
+    @app.before_server_start
+    async def before_server_start(_):
+        1 / 0
+
+    recv = AsyncMock(return_value={"type": "lifespan.startup"})
+    send = AsyncMock()
+    app.asgi = True
+
+    with caplog.at_level(logging.ERROR):
+        await ASGIApp.create(app, {"type": "lifespan"}, recv, send)
+
+    send.assert_awaited_once_with(
+        {"type": "lifespan.startup.failed", "message": "division by zero"}
+    )
+
+
+@pytest.mark.asyncio
+async def test_error_on_lifespan_exception_stop(app: Sanic):
+    @app.before_server_stop
+    async def before_server_stop(_):
+        1 / 0
+
+    recv = AsyncMock(return_value={"type": "lifespan.shutdown"})
+    send = AsyncMock()
+    app.asgi = True
+    await app._startup()
+
+    await ASGIApp.create(app, {"type": "lifespan"}, recv, send)
+
+    send.assert_awaited_once_with(
+        {"type": "lifespan.shutdown.failed", "message": "division by zero"}
+    )