Docs: Add example for gunicorn with uvicorn workers

[byte-bot-app]

Add documentation examples for gunicorn w/ uvicorn workers. See the X post below for a user asking a question on this topic.

Ref:

Bad Messages:

Anyone doing gunicorn w/ unicorn workers?
https://x.com/greeduan/status/1732048433408627005?s=46&t=p4oNoKNiN6WSSW5RCWU7_w
@greeduan
@LitestarAPI
do you have any guide for logging when using gunicorn with uvicorn? Spent a few hours and I still can't figure out how to get the app logs out to the gunicorn logs. Meanwhile with Django it's plug-n-play. Not good for prod.

Reported by peter in Discord: <#919193495690936353>:
no but it would be nice to have an example for that

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[JacobCoffee]

This relates to #2609, partially

[peterschutt]

We were specifically talking about logging with gunicorn workers - great to have a full example, but just want to make sure that the logging topic doesn't get lost.

[provinzkraut]

Thinking about this, I'm not sure if this is actually Litestar specific? The logging setup of gunicorn with uvicorn workers will be exactly the same as for any other ASGI apps. Maybe we don't need to re-invent the wheel here and could just link to existing documentation?

[winstxnhdw]

Thinking about this, I'm not sure if this is actually Litestar specific? The logging setup of gunicorn with uvicorn workers will be exactly the same as for any other ASGI apps. Maybe we don't need to re-invent the wheel here and could just link to existing documentation?

Tried doing it the same way as I did it with FastAPI, but any stray exceptions aren't being logged out.

[provinzkraut]

Litestar's logging behaviour of exception is different than FastAPI's, but this is independent of the server being used. Exceptions aren't logged by default if you're not in debug mode. You can configure this by setting log_exceptions="always" in the logging config: https://docs.litestar.dev/latest/reference/logging/config.html#litestar.logging.config.LoggingConfig.log_exceptions

[winstxnhdw]

Litestar's logging behaviour of exception is different than FastAPI's, but this is independent of the server being used. Exceptions aren't logged by default if you're not in debug mode. You can configure this by setting log_exceptions="always" in the logging config: https://docs.litestar.dev/latest/reference/logging/config.html#litestar.logging.config.LoggingConfig.log_exceptions

It still doesn't log anything out.

class TranscribeController(Controller):
    path = '/transcribe'

    @post()
    async def transcribe(self, data: Annotated[UploadFile, Body(media_type=RequestEncodingType.MULTI_PART)]) -> bytes:
        content = await data.read()
        raise Exception(content)
        return content

def initialise() -> Litestar:
    return Litestar(
        logging_config=LoggingConfig(log_exceptions='always'),
        route_handlers=[TranscribeController],
    )

It works fine on Uvicorn though, but with Gunicorn, it disappears.

[provinzkraut]

How are you running gunicorn? I tested it and it works just fine.

---

In any case, as I mentioned before, this isn't unique to Litestar. It has to do with how gunicorn handles logging. See for example this issue which describes the same behaviour you're experiencing, but with FastAPI.

[winstxnhdw]

How are you running gunicorn? I tested it and it works just fine.

In any case, as I mentioned before, this isn't unique to Litestar. It has to do with how gunicorn handles logging. See for example this issue which describes the same behaviour you're experiencing, but with FastAPI.

I am well familiar with that issue and I have worked around it and still managed to get my exceptions printed.

# gunicorn.conf.py

from server import initialise
from server.config import Config

wsgi_app = f'{initialise.__module__}:{initialise.__name__}()'
reload = False
preload_app = True
bind = f'0.0.0.0:{Config.server_port}'
workers = Config.worker_count
worker_class = 'uvicorn.workers.UvicornWorker'
timeout = 300

[provinzkraut]

That's your config but how are you running it? Is it perhaps inside a container (the bind to 0.0.0.0 suggests that)?

[winstxnhdw]

Nope, it's not containerised. Running it in a poetry venv with poetry run gunicorn and that's it.

[provinzkraut]

What platform are you on?

[provinzkraut]

I don't know why but it seems to be the preload_app = True in your gunicorn config. Adding that causes the logs to disappear.

I've found this issue which seems to describe this exact behaviour, but apparently it has been fixed since.

[winstxnhdw]

I have tested on my personal Windows laptop and within a Linux VPS. I'll try disabling preload_app tomorrow but preload_app is quite important IIRC.

[winstxnhdw]

Yeah, I have confirmed that it is indeed preload_app that's causing this issue, and I believe this is on Litestar's end because all my FastAPI applications are completely fine with this setting.

[JacobCoffee]

not familiar with the issue - just interjecting here quickly - but with the advent of process management in Uvicorn, it may help your particular situation? (to swap from Gunicorn)

[provinzkraut]

Yeah, I have confirmed that it is indeed preload_app that's causing this issue, and I believe this is on Litestar's end because all my FastAPI applications are completely fine with this setting.

This seems odd. I'm still not 100% convinced this is a bug on our end, but would you mind opening a separate issue for this? It's not really a documentation thing in any case, because this should work