How to cache image urls with query strings?

[0liver]

We don't explicitly set the proxy_cache_key - we use the default value
provided by NGINX.

>From the docs at
http://nginx.org/en/docs/http/ngx_http_proxy_module.html#proxy_cache_key I
understood that the query string is part of the cache key - I'm reaching out
for help because it doesn't work as I'd expect.

Posted at Nginx Forum: https://forum.nginx.org/read.php?2,272608,272611#msg-272611