From a3ff0c13b745d6f3eee9cc4ac00f2f95331933c9 Mon Sep 17 00:00:00 2001
From: Adam Hopkins <adam@amhopkins.com>
Date: Fri, 16 Dec 2022 08:56:07 +0200
Subject: [PATCH] ASGI lifespan failure on exception (#2627)

---
 sanic/asgi.py      | 24 +++++++++++++++++++-----
 tests/test_asgi.py | 44 +++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 62 insertions(+), 6 deletions(-)

diff --git a/sanic/asgi.py b/sanic/asgi.py
index c3d669e73b..d8ab4cfaf7 100644
--- a/sanic/asgi.py
+++ b/sanic/asgi.py
@@ -9,7 +9,7 @@
 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 @@ async def __call__(
     ) -> 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:
diff --git a/tests/test_asgi.py b/tests/test_asgi.py
index e612e3fed5..0c76a67f3c 100644
--- a/tests/test_asgi.py
+++ b/tests/test_asgi.py
@@ -8,7 +8,7 @@
 
 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.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 @@ def _request(request: Request):
 
     _, 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"}
+    )