[FEATURE] Make swagger-ui and redoc favicon configurable

Is your feature request related to a problem? Please describe. Both documentation viewers loaded by FastAPI currently use https://fastapi.tiangolo.com/img/favicon.png as their favicon with no way to change it. It’s a nice enough favicon and does the job as a default, but it appears to currently be hardcoded in fastapi/openapi/docs.py, which makes it tricky to change.

Describe the solution you’d like Let the user pass a doc_favicon argument to FastAPI on initialization and fallback on the default if none is provided.

Describe alternatives you’ve considered

• Having all static assets served by FastAPI moved to an internal folder (the HTML templates for the doc pages and possibly the JS bundles for Redoc and Swagger UI), with the option to let the user specify a custom path instead. That one would represent more work and would make custom assets into an all-or-nothing deal, though that isn’t to say that having an internal static folder wouldn’t have its benefits.

[Kilo59]

The swagger_favicon_url argument isn’t featured anywhere in the provided example, and would still lead one to think this isn’t possible unless you pulled up the source code.

A minimal example would be even better. Once/if I figure it out, I’ll submit a PR.

https://github.com/tiangolo/fastapi/blob/4e77737a3f7bf2608132ea170e9ff013b5af6732/fastapi/openapi/docs.py#L14

[tiangolo]

Using static assets is documented at https://fastapi.tiangolo.com/advanced/extending-openapi/#self-hosting-javascript-and-css-for-docs

It was added a while ago but I hadn’t commented about it here. 😬

I think that should solve the original problem 🚀 So I’ll close this issue now. But feel free to add more comments or issues.