[QUESTION] How can I use Gunicorns SCRIPT_NAME with FastAPI?

First check

• I used the GitHub search to find a similar issue and didn’t find it.
• I searched the FastAPI documentation, with the integrated search.
• I already searched in Google “How to X in FastAPI” and didn’t find any information.

Description

Is it possible to allow routes to be prefixed using Gunicorn’s support for the SCRIPT_NAME env variable? I read the discussion in #461 but could not find any other working solution than manually prepending the prefixed url to each route.

Additional context

What I would like to do is basically have a route prefix by setting: os.environ["SCRIPT_NAME"] = "/a/b/c/d/e" and then allowing Gunicorn to route for example

@app.get("/hello")
def read_root():
    return {"Hello": "World"}

to /a/b/c/d/e/hello.

I tried running the Uvicorn + Gunicorn combination using gunicorn main:app -w 4 -k uvicorn.workers.UvicornWorker to achieve this. It will simply ignore the prefix and keep on routing to /hello instead.

Gunicorn will do this out of the box if the env var is present when serving a Flask or Django app.

[Midnighter]

As shown in my proof-of-concept, you still have to subclass the uvicorn worker similar to the following:

from starlette.config import Config
from uvicorn.workers import UvicornWorker


config = Config()


class ConfigurableWorker(UvicornWorker):
    """
    Define a UvicornWorker that can be configured by modifying its class attribute.
    All of the command line options for uvicorn are potential configuration options
    (see https://www.uvicorn.org/settings/ for the complete list).
    """

    #: dict: Set the equivalent of uvicorn command line options as keys.
    CONFIG_KWARGS = {
        "root_path": config("SCRIPT_NAME", default=""),
        "proxy_headers": True,
    }

[tiangolo]

@Midnighter I think that’s worth a PR to Uvicorn ✔️