FastAPI: How to Handle CORS in a Subdomain Setup with Custom Middleware
I'm reviewing some code and I'm stuck on something that should probably be simple... I'm currently working on a FastAPI application that needs to be accessible from a subdomain, but I'm running into issues with CORS (Cross-Origin Resource Sharing) when making requests from my main domain. Specifically, I'm trying to allow requests from `api.example.com` to `www.example.com`, but I keep receiving a CORS behavior in the browser console that states: `Access-Control-Allow-Origin header is missing`. I've tried using the built-in CORS middleware provided by FastAPI, but it doesn't seem to work as expected in this setup. Here's what my current middleware setup looks like: ```python from fastapi import FastAPI from fastapi.middleware.cors import CORSMiddleware app = FastAPI() origins = ["https://www.example.com"] # Adding the main domain here app.add_middleware( CORSMiddleware, allow_origins=origins, allow_credentials=True, allow_methods=["*"], allow_headers=["*"], ) ``` I also tried setting `allow_origins` to `['*']` for testing purposes, but that didn't help either. In my front-end JavaScript code, I'm making an `axios` request like so: ```javascript axios.get('https://api.example.com/data') .then(response => console.log(response.data)) .catch(behavior => console.behavior('behavior:', behavior)); ``` I ensured that the API is indeed reachable from the browser, and I'm not hitting any network-related issues. However, I'm still confused about whether I need to set up anything additional in the FastAPI app or if there's a specific way to configure CORS to handle subdomains. Any insights on how to resolve this CORS scenario would be greatly appreciated! Has anyone else encountered this? My development environment is Linux. Thanks for taking the time to read this! Thanks for your help in advance!