CancelledError being raised when starting app in Argo CD

[ishaan-mehta]

I have a FastAPI app that uses uvicorn, and when I run locally with Docker on colima, I never encounter this error, but when I run that same app in Argo CD, I keep seeing the following error and the app immediately shuts down:

INFO:     Application startup complete.
INFO:     Uvicorn running on http://0.0.0.0:8000 (Press CTRL+C to quit)
ERROR:    Traceback (most recent call last):
  File "/usr/local/lib/python3.12/site-packages/starlette/routing.py", line 700, in lifespan
    await receive()
  File "/usr/local/lib/python3.12/site-packages/uvicorn/lifespan/on.py", line 137, in receive
    return await self.receive_queue.get()
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/asyncio/queues.py", line 158, in get
    await getter
asyncio.exceptions.CancelledError

(This is transient, however — very rarely, the app does manage to get past this and start without issue.)

As far as I can tell, this error is never supposed to actually surface to the user. How can I solve this? Is this an issue with uvicorn? An issue with starlette? (I am not using Ctrl-C or interacting with the app at all, which I have seen suggested on similar discussions online.)

[graingert]

@ishaan-mehta do you have a minimal reproducible example?

or if you just have a paste of your whole app I can try to repro?

cc @Wurstnase @hunter2009pf if you have an MRE or can share your code

[Wurstnase]

Sorry, I could not remember my problem anymore. I think it was something with pytest_asyncio/playwright and uvicorn. But I solved it somehow.