user_key_codebox.py

import requests
import json

# I'll use direct API call, to show the logic of it - I don't want to cloud it with how certain libraries might work

# we check if the user_key was passed to the webhook
user_key = ARGS["POST"].get("user_key","")
if not user_key:
    user_key = ARGS["GET"].get("user_key","")
    
# you this payload when testing inside a codebox
# {"POST": {"user_key":""}, "GET": {}}

api_key = ""
url = "https://api.syncano.io/v1/instances/{instance}/classes/test_class/objects/?api_key={api_key}".format(instance=META["instance"],api_key=api_key)
if user_key:
    url = "{url}&user_key={user_key}".format(url=url,user_key=user_key)
r = requests.get(url)

response = HttpResponse(status_code=200, content=json.dumps(r.json()), content_type='text/json');
set_response(response);