Scripts that will reliably reproduce an AnyIO.EndOfStream error when using ContextMiddleware

Dockerfile

# Note, I'm not running the docker process directly, instead I'm building the container and bashing in to start 
# `$ python fast_server.py` and `python fast_client.py`. 

FROM python:3.9.7

ARG REQUIREMENTS_FILE=requirements-dev.txt
WORKDIR /code
ADD requirements.txt requirements-*.txt /code/

RUN pip install -r $REQUIREMENTS_FILE
ADD . /code/

VOLUME /code

# CMD ["ddtrace-run", "--profiling", "python", "-m", "fast_app"]

fast_app.py

import time
from fastapi import FastAPI, Request

from starlette.middleware.cors import CORSMiddleware
from starlette_context.middleware import ContextMiddleware
from starlette_context import plugins

app = FastAPI()

# Commenting out line 11 resolves the error:
app.add_middleware(ContextMiddleware, plugins=[plugins.CorrelationIdPlugin()])


@app.middleware("http")
async def middleware(request: Request, call_next):
    return await call_next(request)


@app.get("/")
def read_root():
    time.sleep(4)
    return {"Hello": "World"}

fast_client.py

import requests

count = 0

while True:
    try:
        r = requests.get("http://0.0.0.0:8100/", timeout=2)
    except requests.exceptions.ReadTimeout:
        count += 1
        print(f"{count}")

fast_server.py

if __name__ == "__main__":
    import uvicorn

    uvicorn.run(
        "fast_app:app",
        host="0.0.0.0",
        port=8100,
        reload=False,
        debug=False,
    )

requirements-dev.txt

-r requirements.txt
black==20.8b1
coverage
pydevd-pycharm~=213.5744.248
pdbpp

requirements.txt

fastapi~=0.75.2
pytest==6.2.5
pytest-aiohttp==0.3.0
aiohttp==3.8.1
aiomcache>=0.5.2, < 0.7.0
aiocache[memcached]==0.11.1
aioresponses~=0.7.2
hvac==0.11.2
pydantic==1.9.0
ddtrace==0.59.1
fnc~=0.5.3
mysqlclient==2.0.3
pycryptodome==3.14.1
python-json-logger==2.0.2
requests==2.27.1
okta==2.3.1
okta-jwt-verifier==0.2.3
hvac==0.11.2
sqlalchemy==1.4.26
starlette-context==0.3.3
uvicorn==0.17.3
tenacity~=8.0.1
datadog-api-client[async]==1.10.0

stacktrace

Traceback (most recent call last):
  File "/usr/local/lib/python3.9/site-packages/starlette/middleware/base.py", line 41, in call_next
    message = await recv_stream.receive()
  File "/usr/local/lib/python3.9/site-packages/anyio/streams/memory.py", line 101, in receive
    raise EndOfStream
anyio.EndOfStream

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/local/lib/python3.9/site-packages/uvicorn/protocols/http/h11_impl.py", line 364, in run_asgi
    result = await app(self.scope, self.receive, self.send)
  File "/usr/local/lib/python3.9/site-packages/uvicorn/middleware/proxy_headers.py", line 75, in __call__
    return await self.app(scope, receive, send)
  File "/usr/local/lib/python3.9/site-packages/fastapi/applications.py", line 261, in __call__
    await super().__call__(scope, receive, send)
  File "/usr/local/lib/python3.9/site-packages/starlette/applications.py", line 112, in __call__
    await self.middleware_stack(scope, receive, send)
  File "/usr/local/lib/python3.9/site-packages/starlette/middleware/errors.py", line 181, in __call__
    raise exc
  File "/usr/local/lib/python3.9/site-packages/starlette/middleware/errors.py", line 159, in __call__
    await self.app(scope, receive, _send)
  File "/usr/local/lib/python3.9/site-packages/starlette/middleware/base.py", line 63, in __call__
    response = await self.dispatch_func(request, call_next)
  File "/code/fast_app.py", line 21, in middleware
    return await call_next(request)
  File "/usr/local/lib/python3.9/site-packages/starlette/middleware/base.py", line 45, in call_next
    raise RuntimeError("No response returned.")
RuntimeError: No response returned.