HAProxy使用服务器从DOWN到UP时

I have a server that runs HAProxy to load balance our mysql servers. Some of the server may go down when we have low average load for a extensive period of time, but, in the future, if the load becomes high again, those servers goes up automatically. The problem is when an instance goes down, HAProxy never looks to it again, so when the instance is up again, it is ignored. To fix this we reboot when needed.I have a server that runs HAProxy to load balan