API Gateway rewrite URL

[typexy]

Hi,

I have an app which calls an external provider which needs a key in the URL. For security reasons I can't include the key in the app to call the external API directly. Therefore I need to proxy this URL / rewrite URL and attach the key in the URL like following:

https://api.xxx.com/maps/3/2/2.png

to

https://api.xxx.com/maps/3/2/2.png?key=xxxxxxxx

Do you have an idea how to solve it with gcp API gateway?