use nginx proxy to local port application.

nginx-proxy-port.conf

location / {
  proxy_pass          http://localhost:3000;
  
  proxy_set_header    Host             $host;
  proxy_set_header    X-Real-IP        $remote_addr;
  proxy_set_header    X-Forwarded-For  $proxy_add_x_forwarded_for;

  # websocket support
  # proxy_set_header    Upgrade          $http_upgrade;
  # proxy_set_header    Connection       "upgrade";
  # proxy_http_version  1.1;
 
  # ssl support
  # proxy_set_header    X-Client-Verify  SUCCESS;
  # proxy_set_header    X-Client-DN      $ssl_client_s_dn;
  # proxy_set_header    X-SSL-Subject    $ssl_client_s_dn;
  # proxy_set_header    X-SSL-Issuer     $ssl_client_i_dn;
  
  # proxy_read_timeout 1800;
  # proxy_connect_timeout 1800;
}