etherpad_ynh/conf/nginx.conf

location PATHTOCHANGE {
       if ($scheme = http) {
            rewrite ^ https://$server_name$request_uri? permanent;
       }
       rewrite                /PATHTOCHANGE/(.*) /$1 break;
       rewrite                ^/PATHTOCHANGE$ /PATHTOCHANGE/ permanent;
       proxy_pass             http://localhost:9001/;
       proxy_redirect         / /PATHTOCHANGE/;
       proxy_set_header       Host $host;
       proxy_buffering off;
}