Does FastAPI support subdomains like Flask?

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Example Code

from flask import Flask

app = Flask(__name__)

# Add these definitions to the hosts file:
# local.dev        127.0.0.1
# api.local.dev    127.0.0.1
app.config["SERVER_NAME"] = "local.dev:5000"

@app.route("/")
def home():
    return "Home page"

@app.route("/default-subdomain")
def default_subdomain():
    return "Default subdomain"

@app.route("/", subdomain="api")
def api_home():
    return "API home"

Description

Flask has subdomains for its routes: https://flask.palletsprojects.com/en/2.2.x/api/#url-route-registrations - does FastAPI have something similar? If not, and it has to be done with a Nginx reverse proxy and two separate FastAPI instances (e.g. default subdomain on port 8000 and the api subdomain on port 8001), how would I go about sharing internal state e.g. auth tokens and user id between two different FastAPI apps?

Operating System

Linux, Windows

Operating System Details

No response

FastAPI Version

0.79.0

Python Version

3.10.5

Additional Context

No response

[kieled]

Hi. I am aware it exists in Flask, but I am asking when it will be implemented in FastAPI.

Understand that it will never be implemented. This is not a responsibility that any web framework should have. There are already reverse proxies for this, such as traefik or nginx

Understand that when doing it this way (e.g. using URI paths for different subdomains in nginx/traefik config), all routes from the same web app will become available on both the main domain and any other subdomains you have set up this way. This is the whole reason why almost all other frameworks have support for this.

I don’t understand why you are talking down this feature when all the major and widely used frameworks have this implemented. It has existed for years.

You can do it with reverse proxy. I just think that web framework should perform only the necessary functions. A framework should be fast and lightweight. He should not become a monster trying to capture everything and everywhere, and do the best. We saw what happened to the performance of django, although it brought a lot of things. I hope the original idea of FastAPI stays with him. Why bother with routing if there are already wonderful solutions on the market.

[JarroVGIT]

FastAPI has no support for subdomains. You don’t necessarily have to use two FastAPI instances if you use NGINX. You could just point subdomain.example.com to api.example.com/router/ and example.com to api.example.com. You just have to make sure that all your subdomain paths are properly mapped, so I would suggest you would use a separate APIRouter with a fixed prefix=.

It might get confusing, and also note that when people go to example.com/router/endpoint that it would be a valid request. This solution is just some sugarcoating in that respect.