[dnsdist] server policy to failover to another pool

[Chris]

Hi

On 5/10/2017 5:05 AM, Justin Valentini wrote:
> Hi,
> 
> I'm trying to create a Lua server policy to use the least outstanding 
> policy on one pool but send traffic to another pool if none of the 
> servers in the first pool are up.

I don't have a solution for the way that you want to do this 
specifically, but I have a lua policy you can use and with some changes 
to your setup this can be achieved.

1. Use the orderedLeastOutstanding policy from here: 
https://github.com/sysadminblog/dnsdist-configs/blob/master/orderedLeastOutstanding.lua

2. Only use the primary pool, add your primary servers as order 1 and 
the secondary servers as order 2.

Queries will only be directed to the servers with the order "1" 
normally, if they are all marked as down then they will be directed to 
the servers with the order "2".