upstream.conf

upstream backend {
  192.168.0.1:8000; #server 1
  192.168.0.2:8001; #server 2
  
  balancer_by_lua_block {
    //write your round robin code here
    local host, port = picked_server()
    if not host and not port then
      ngx.status = ngx.HTTP_INTERNAL_SERVER_ERROR
      ngx.say("no live upstream")
      ngx.exit(ngx.HTTP_OK)
      return
    end
    
    local ok, err = balancer.set_current_peer(host, port)
    if not ok then
      ngx.status = ngx.HTTP_INTERNAL_SERVER_ERROR
      ngx.say("failed to set current peer")
      ngx.exit(ngx.HTTP_OK)
      return
    end
  }
}