User-Agent based ACL - conditional redirecting rules

server-1.conf

log_format client_ip "$remote_addr";

map $http_user_agent $whitelist_ua {
    default       1;
    "~*curl"      0;
}

server {
  listen 80;

  access_log off;

  if ($whitelist_ua) {
    rewrite ^/.* https://v.mib.cc redirect;
  }

  location / {
    access_log /var/log/nginx/client_ip.log client_ip;

    return 200 "OK\nHello world!\n";
  }
}