Keep client ip address

> I have the following system:
> - a machine doing NAT that sends all connections of port 9000 (testing
> purposes) to a machine turning nginx 4.14 at 192.168.1.21.
> - This machine sends the requests to 192.168.1.15, a machine running
> apache with mod_python and django.
>
> The forwarding works just great, but I would like the logs of Apache
> to use the client's IP, not 192.168.1.21, in order not to change
> anything for the different sites administrators.
>
> In order to do this, I've this configuration:
>
>    server {
>        listen           80;
>        server_name      www.mysite.com;
>        # vhost specific logs
>        access_log       /var/log/nginx/www.mysite.com.access.log combined;
>
>        #Set the max size for file uploads to 50Mb
>        client_max_body_size  50M;
>
>        location / {
>            proxy_pass   http://192.168.1.15;
>            proxy_redirect          off;
>            proxy_set_header        Host             $host;
>            proxy_set_header        X-Real-IP        $remote_addr;
>            proxy_set_header        X-Forwarded-For  $proxy_add_x_forwarded_for;
>
>            set_real_ip_from   192.168.1.0/24;