When on_shutdown function raises error, starlette doesn't catch it and uvicorn thinks that lifespan is not supported #1138
Description
Checklist
- The bug is reproducible against the latest release and/or
master. - There are no similar issues or pull requests to fix it yet.
Describe the bug
When one of the on_shutdown functions raises an error
To reproduce
from starlette.applications import Starlette
async def fail():
raise Exception()
app = Starlette(on_shutdown=[fail])(Doesn't matter if the function is async or not)
uvicorn app:app --log-level trace
Expected behavior
The exception is caught, reported, and Starlette shuts down properly
Actual behavior
Logs:
INFO: Started server process [22310]
INFO: Waiting for application startup.
TRACE: ASGI [1] Started scope={'type': 'lifespan', 'asgi': {'version': '3.0', 'spec_version': '2.0'}}
TRACE: ASGI [1] Receive {'type': 'lifespan.startup'}
TRACE: ASGI [1] Send {'type': 'lifespan.startup.complete'}
INFO: Application startup complete.
INFO: Uvicorn running on http://127.0.0.1:8000 (Press CTRL+C to quit)
^C
INFO: Shutting down
INFO: Waiting for application shutdown.
TRACE: ASGI [1] Receive {'type': 'lifespan.shutdown'}
TRACE: ASGI [1] Raised exception
INFO: ASGI 'lifespan' protocol appears unsupported.
INFO: Application shutdown complete.
INFO: Finished server process [22310]
Note that the TRACE messages are hidden, and all that is printed is "ASGI 'lifespan' protocol appears unsupported."
Debugging material
When I run uvicorn with --lifespan on, these logs appear:
Details
INFO: Started server process [22568]
INFO: Waiting for application startup.
TRACE: ASGI [1] Started scope={'type': 'lifespan', 'asgi': {'version': '3.0', 'spec_version': '2.0'}}
TRACE: ASGI [1] Receive {'type': 'lifespan.startup'}
TRACE: ASGI [1] Send {'type': 'lifespan.startup.complete'}
INFO: Application startup complete.
INFO: Uvicorn running on http://127.0.0.1:8000 (Press CTRL+C to quit)
^C
INFO: Shutting down
INFO: Waiting for application shutdown.
TRACE: ASGI [1] Receive {'type': 'lifespan.shutdown'}
TRACE: ASGI [1] Raised exception
ERROR: Exception in 'lifespan' protocol
Traceback (most recent call last):
File "/tmp/issue/env/lib/python3.8/site-packages/uvicorn/lifespan/on.py", line 55, in main
await app(scope, self.receive, self.send)
File "/tmp/issue/env/lib/python3.8/site-packages/uvicorn/middleware/proxy_headers.py", line 45, in __call__
return await self.app(scope, receive, send)
File "/tmp/issue/env/lib/python3.8/site-packages/uvicorn/middleware/message_logger.py", line 65, in __call__
raise exc from None
File "/tmp/issue/env/lib/python3.8/site-packages/uvicorn/middleware/message_logger.py", line 61, in __call__
await self.app(scope, inner_receive, inner_send)
File "/tmp/issue/env/lib/python3.8/site-packages/starlette/applications.py", line 112, in __call__
await self.middleware_stack(scope, receive, send)
File "/tmp/issue/env/lib/python3.8/site-packages/starlette/middleware/errors.py", line 146, in __call__
await self.app(scope, receive, send)
File "/tmp/issue/env/lib/python3.8/site-packages/starlette/exceptions.py", line 58, in __call__
await self.app(scope, receive, send)
File "/tmp/issue/env/lib/python3.8/site-packages/starlette/routing.py", line 569, in __call__
await self.lifespan(scope, receive, send)
File "/tmp/issue/env/lib/python3.8/site-packages/starlette/routing.py", line 540, in lifespan
async for item in self.lifespan_context(app):
File "/tmp/issue/env/lib/python3.8/site-packages/starlette/routing.py", line 483, in default_lifespan
await self.shutdown()
File "/tmp/issue/env/lib/python3.8/site-packages/starlette/routing.py", line 528, in shutdown
handler()
File "./app.py", line 5, in fail
raise Exception()
Exception
INFO: Application shutdown complete.
INFO: Finished server process [22568]
Environment
- OS: Ubuntu 20.04.1 LTS
- Python version: 3.8.5
click==7.1.2
h11==0.12.0
starlette==0.14.2
uvicorn==0.13.3
Additional context
Somebody likely ran into this here: https://stackoverflow.com/q/64512286/7292139