[Python] FastAPI / uvicorn (or hypercorn): where is my root-path?

Based on a few FastAPI tutorials, including this, I made a simple FastAPI app:

from fastapi import FastAPI, Request
app = FastAPI() # also tried FastAPI(root_path="/api/v1")

@app.get("/app")
def read_main(request: Request):
return {"message": "Hello World", "root_path": request.scope.get("root_path")}


Which I want to have at a path other than root (e.g. /api/vi). Again based on most tutorials and common sense, I tried to start it with e.g.:

uvicorn main:app --root-path /api/v1


The service comes up ok (on http://127.0.0.1:8000), however, the root-path seems to be ignored, i.e., any GET request to http://127.0.0.1:8000/ gives:

message "Hello World"
root_path "/api/v1"


and any GET request to http://127.0.0.1:8000/api/v1 gives:

detail "Not Found"


I would expect the requests to produce the reverse outcomes. What is going on here?!

I also tried initializing FastAPI with FastAPI(root_path="/api/v1"), as well as switching to hypercorn without avail.

Details of the versions of apps (I might have tried a few others as well, though these should be the latest tried):

python 3.9.7 hf930737_3_cpython conda-forge
fastapi 0.85.1 pyhd8ed1ab_0 conda-forge
uvicorn 0.20.0 py39h06a4308_0
hypercorn 0.14.3 py39hf3d152e_1 conda-forge

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