SentryAsgiMiddleware not compatible with Uvicorn 0.13.0

On December 8th Uvicorn updated from 0.12.3 to 0.13.0. This results in an error at startup, see output with minimal example. When downgrading Uvicorn to 0.12.3 the example runs fine.

Why this error is thrown or which changes resulted in the error, I have no clue. Could you help me with this?

app.py

from sanic import Sanic
from sentry_sdk.integrations.asgi import SentryAsgiMiddleware

app = SentryAsgiMiddleware(Sanic(__name__))

requirements.txt

sanic==20.9.1
sentry-sdk==0.19.4
uvicorn==0.13.0

Command to run:

uvicorn app:app --port 5000 --workers=1 --debug --reload

Output:

INFO:     Uvicorn running on http://127.0.0.1:5000 (Press CTRL+C to quit)
INFO:     Started reloader process [614068] using statreload
Process SpawnProcess-1:
Traceback (most recent call last):
  File "/usr/lib/python3.9/multiprocessing/process.py", line 315, in _bootstrap
    self.run()
  File "/usr/lib/python3.9/multiprocessing/process.py", line 108, in run
    self._target(*self._args, **self._kwargs)
  File "/home/lander/.local/share/virtualenvs/san-iJ5wdX60/lib/python3.9/site-packages/uvicorn/subprocess.py", line 61, in subprocess_started
    target(sockets=sockets)
  File "/home/lander/.local/share/virtualenvs/san-iJ5wdX60/lib/python3.9/site-packages/uvicorn/server.py", line 48, in run
    loop.run_until_complete(self.serve(sockets=sockets))
  File "uvloop/loop.pyx", line 1456, in uvloop.loop.Loop.run_until_complete
  File "/home/lander/.local/share/virtualenvs/san-iJ5wdX60/lib/python3.9/site-packages/uvicorn/server.py", line 55, in serve
    config.load()
  File "/home/lander/.local/share/virtualenvs/san-iJ5wdX60/lib/python3.9/site-packages/uvicorn/config.py", line 319, in load
    elif not inspect.signature(self.loaded_app).parameters:
  File "/usr/lib/python3.9/inspect.py", line 3118, in signature
    return Signature.from_callable(obj, follow_wrapped=follow_wrapped)
  File "/usr/lib/python3.9/inspect.py", line 2867, in from_callable
    return _signature_from_callable(obj, sigcls=cls,
  File "/usr/lib/python3.9/inspect.py", line 2409, in _signature_from_callable
    sig = _signature_from_callable(
  File "/usr/lib/python3.9/inspect.py", line 2242, in _signature_from_callable
    raise TypeError('{!r} is not a callable object'.format(obj))
TypeError: <member '__call__' of 'SentryAsgiMiddleware' objects> is not a callable object

[adamantike]

I think this issue can be closed, after the implemented fixes.

[florimondmanca]

I don’t see how the middleware exposes itself as app factory.

It doesn’t, but due to the __call__ trick the code that Uvicorn was using to decide whether an app was a factory or not was failing. 😃