[Feature Request] Uvicorn integration

[alimcmaster1]

🚀 Feature Request

Firstly thank you for open sourcing this - documentation is excellent too!.

Motivation

Often ASGI/WSGI python webserver frameworks are launched with their own wrapper module such as gunicorn, uvicorn and hypercorn.

Example as per the uvicorn quickstart guide.
(note the run command: uvicorn example:app)

The uvicorn command then runs this main module.

If one wishes to use hydra for configuration management in the uvicorn examples they would need to rewrite some code from the above module perhaps:

import hydra
from uvicorn.supervisors import Multiprocess
from uvicorn.config import Config
from uvicorn.main import Server


async def app(scope, receive, send):
    assert scope['type'] == 'http'
    await send({
        'type': 'http.response.start',
        'status': 200,
        'headers': [
            [b'content-type', b'text/plain'],
        ]
    })
    await send({
        'type': 'http.response.body',
        'body': b'Hello, world!',
    })


@hydra.main()
def run(cfg):
    print(cfg.pretty())

    config = Config(app)
    server = Server(config=config)
    sock = config.bind_socket()
    supervisor = Multiprocess(config)
    supervisor.run(server.run, sockets=[sock])


if __name__ == "__main__":
    run()

Pitch

Describe the solution you'd like

A very open ended question but what are peoples thoughts on developing a way to make these libraries work together

Goals:

• users don't have to duplicate code.
• make it easier to pass the hydra configuration into the uvicorn application

Are you willing to open a pull request?

• Yes

cc. @tomchristie

[omry]

Hi @alimcmaster1.
Thanks for the feature request, and I appreciate your kind words!
I am not a web developer (any longer), and I was not aware of those frameworks (although I did use WSGI as a user at some point).

The execution model is one of the areas where Hydra is not very flexible right now.
I will want to take a closer look at Uvicorn to see what a nice integration might look like.
On the surface this sounds like more a feature request for Uvicorn than to Hydra (To allow accepting an external configuration).

I suggest that you try using Hydra with Uvicorn for a while (even if the integration is not clean) to see what works well and what doesn't work well before we start thinking about what needed to be changed in Hydra to support this better.

[omry]

Generally speaking, Hydra is lower level than traditional frameworks.
Most frameworks in ML (I am not talking about Uvicorn here), are provide - apart from the value in their actual domain - a solution for a common set of problems (Command line interface, configuration files, remote launching, logging etc).
For such frameworks, it's best if they are modified to use Hydra as a base because it can solve all those problems for them.
The extra advantage here is that after doing that, suddenly they can easily be integrated into a Hydra app that may be using some other such frameworks at the same time. something like this would normally be very painful but with Hydra it's a breeze.

I do not have a good mental model of Uvicorn right now.
From the little I see, it seems that they went the way of uvicorn python_mdule as a launching mechanism. this is pretty hard to integrate with for something like Hydra.

Beyond configuring itself, does Uvicorn cocerns itself at all with how the user's web server would configure itself?
I saw that Uvicorn has a simple configuration object.
If this is the extent to which Uvicorn is concerning itself with configuration, it may be pretty straight forward to change (Or wrap) it in a way that takes advantage of Hydra more naturally.

In your example, what I am not seeing is how you use Hydra's config to configure Uvicorn and how you are using it to configure the behavior of the actual app.

[omry]

@hydra.compose API that is planned in #219 might be helpful here.

[omry]

directus-api looks like a pretty solid example of an integration between Hydra and Uvicorn.

https://github.com/devova/directus-api/

[alimcmaster1]

@omry - Thanks for your detailed responses - appreciate it.

Yes agree #219 - looks interesting - will keep an eye out and try this when available.

Thanks very much for the example - that's a neat way of integrating uvicorn and hydra!

[omry]

#219 is now landed (and is available in the Hydra 0.11). I ended up with an experimental API to perform composition.
See this (The website is a bit outdated but should be fixed soon).

It would be great if anyone interested in Uvicorn and Hydra contribute a minimal and educational example of how they think is a good way to integrate them.

[omry]

Closing, this should be possible via the compose API or following the example I pointed to.