なぜかリクエストの度にlookupしてくれない。streamの設定

nginx-stream

stream {
  upstream deis {
    server deis-elb-01.aya.staging:2222;
  }

  server {
    listen 2222;

    # resolve ELB's hostname to IP
    mruby_stream_code '
      host = "deis-elb-01.aya.staging"
      port = "2222"
      c = Nginx::Stream::Connection.new "deis"
      c.upstream_server = Addrinfo.tcp("#{host}", nil).ip_address << ":#{port}"
    ';

    proxy_pass deis;
  }
}