events {
    worker_connections 1024;
  }

http {
  access_log off;
  error_log /dev/null crit;

  upstream backend_pool {
    least_conn;
    server api1:9999;
    server api2:9999;
    server api3:9999;
    keepalive 32;
  }

  server {
    listen 9999 default_server;

    location / {
      proxy_pass http://backend_pool;
      proxy_http_version 1.1;
      proxy_set_header Connection "";
      proxy_buffering off;
      proxy_cache off;
      proxy_store off;
      proxy_connect_timeout 1s;
      proxy_send_timeout 5s;
      proxy_read_timeout 5s;
      proxy_next_upstream error timeout invalid_header http_500 http_502 http_503;
    }
  }
}