Status 502: [WARNING] Invalid HTTP request received.

I was trying to build a typeahead search API. This API gets called in quick succession, and I am getting an intermittent 502 response.

To Reproduce Not sure how to reproduce this, as normal API calls, when spaced out, are working fine.

Expected behavior - Logs

2019-11-05T06:17:55.447961016Z [2019-11-05 06:17:55 +0000] [16] [INFO] ('100.96.0.56', 50964) - "POST <<URL_NAME>> HTTP/1.1" 200

Noted Intermittent Behaviour - Logs

2019-11-05T06:17:56.459601437Z [2019-11-05 06:17:56 +0000] [16] [WARNING] Invalid HTTP request received.

Environment:

• OS: Debian GNU/Linux 10 (buster)
• FastAPI Version : 0.38.1
• Python version: 3.6
• Server: Gunicorn with 2 Uvicorn workers (see config file below)

bind = "0.0.0.0:4000"
workers = 2
worker_class = "uvicorn.workers.UvicornWorker"
timeout = 300

Additional context

• Added timeout in config after searching on the internet, did not work

[gautamsinghania95]

Hi,

Closing the issue as it was resolved from my end.

Resolution: The deployment platform only accepted HTTP 1.1 calls, but the uvicorn worker class I was using uvicorn.workers.UvicornWorker was sending both types of request. Replacing it with uvicorn.workers.UvicornH11Worker resolved it.

Thanks.

[Saftophobia]

According to https://github.com/tiangolo/uvicorn-gunicorn-docker/pull/38, you can set it as an environment variable now WORKER_CLASS="uvicorn.workers.UvicornH11Worker"