Expose the inputs and outputs in the openapi.json files

[MatthieuBizien]

Is your feature request related to a problem? Please describe.

Gradio documents the API in the /api route, which is really nice for understanding an API.

Having a machine-readable version of that page would be very useful for automatic verification of the coherency of the gradio, including:

• Do the caller provide all the necessary inputs?
• Are the inputs correctly typed and formatted?
• What are the acceptable values of dropdowns, sliders?
• What are the labels of the inputs and outputs?

Describe the solution you'd like

The standard place for that information would be /openapi.json , that can represent data models, including:

• Integer and Float (incl. minimum, maximum, multipleOf)
• Text
• Enums <-> Dropdown
• Files

The JSON keywords also match most of the options of the Gradio inputs, incl.

• description for label
• minimum, maximum

Additional context

Because Gradio use FastAPI + Pydantic + Swagger, it could be enough to define dynamic Pydantic models and use them when creating the application.

An alternative solution would be to just expose the data of the /api route as json, without using the standard.

[aliabd]

Hey @MatthieuBizien thanks for the detailed notes here! We discussed this suggestion internally and feel it's a bit too early. I'm going to close this issue but we'll take another look at it sometime in the future.

In any case, if you're strongly in favor of this, we would be open for a PR.

[aliabd]

Actually, we decided to keep it open for now :)

[abidlabs]

Same as #2364, closing as there is more activity on that one. Thanks for the request @MatthieuBizien

[abidlabs]

Reopening this. For the client, we already have the ability to programmatically inspect the APIs using the /info routes, but that is a custom json format. Would be good to also have a route, maybe /openapi.json (the standard fastapi route I think) that exposes in openapi format

Slack discussion: https://huggingface.slack.com/archives/C02SPHC1KD1/p1680887663305069?thread_ts=1680694519.500639&cid=C02SPHC1KD1