Update app.py

app.py

@@ -9,10 +9,9 @@ from google.oauth2 import service_account
 
 
 def get_token(function_url):
-    with open("cf_key.json", "w") as f:
-        json.dump(json.loads(os.environ.get("CF_KEY")), f, ensure_ascii=False, indent=2)
-    credentials = service_account.IDTokenCredentials.from_service_account_file(
-        "cf_key.json", target_audience=function_url
+    cf_key = json.loads(os.environ.get("CF_KEY"))
+    credentials = service_account.IDTokenCredentials.from_service_account_info(
+        cf_key, target_audience=function_url
     )
     if credentials.valid is False:
         credentials.refresh(Request())