app.py

from fastapi import FastAPI, Request
import httpx
from starlette.responses import RedirectResponse

app = FastAPI()

@app.get("/forward/")
async def forward(request: Request):
    # Extract query parameters as a dictionary
    query_params = dict(request.query_params)
    
    # Extract the URL to forward to (param1)
    forward_url = query_params.pop('param1', None)
    
    # Check if the forward URL is present
    if not forward_url:
        return {"error": "param1 (forward URL) is required"}
    
    # Prepare the new URL with remaining query parameters
    # This assumes that the forward URL does not already have query parameters.
    if query_params:  # If there are other parameters to forward
        params_as_str = "&".join([f"{key}={value}" for key, value in query_params.items()])
        forward_url_with_params = f"{forward_url}?{params_as_str}"
    else:
        forward_url_with_params = forward_url
    
    # Forward the request to the new URL using httpx for asynchronous HTTP requests
    async with httpx.AsyncClient() as client:
        response = await client.get(forward_url_with_params)
    
    # For simplicity, we're directly returning the response from the forwarded URL
    # In a real application, you might want to handle different response scenarios
    return response.json()

# To run the server:
# uvicorn app:app --reload