Uses variable in proxy_pass for normal proxy hosts

docker/rootfs/etc/nginx/conf.d/include/proxy.conf

@@ -1,8 +1,9 @@
+set              $upstream $forward_scheme://$server:$port$request_uri;
 add_header       X-Served-By $host;
 proxy_set_header Host $host;
 proxy_set_header X-Forwarded-Scheme $scheme;
 proxy_set_header X-Forwarded-Proto  $scheme;
 proxy_set_header X-Forwarded-For    $remote_addr;
 proxy_set_header X-Real-IP          $remote_addr;
-proxy_pass       $forward_scheme://$server:$port;
+proxy_pass       $upstream;