[dnsdist] Backend Questions

[Otto Moerbeek]

On Wed, Nov 02, 2022 at 01:38:10PM +0100, Klaus Darilion via dnsdist wrote:

> (resent to the list)
> 
> Hi Remi!
> 
> > On 07/10/2022 10:53, Klaus Darilion via dnsdist wrote:
> > 
> > > We use dnsdist with 1 single backend server (PDNS). So if this backend
> > > is overloaded, dnsdist will detect the backend as DOWN. Hence, the only
> > > server for this backend pool down. How will dnsdist behave if all
> > > servers for a backend pool are down? Will it stop senden queries to the
> > > backend, or will it still send queries to the DOWN server as there is no
> > > UP server available?
> > 
> > All of the built-in load balancing policies will stop forwarding queries
> > when all the servers in the selected pool are down. It would be possible
> > to write a custom load-balancing in Lua that does not do that, of
> > course, but I don't think that's what you want in that case.
> > 
> > > So it may be useful to disable healthchecks completely. How can this be
> > > done?
> > 
> > You can force a server in the "up" state using the 'setUp()' method, see
> > [1].
> 
> Shouldn't newServer(...healthCheckMode='UP') also work? In my case it does not work. 
> I have set healthCheckMode='UP' but:
> showServers show status as "up" whereas after setUp() the status is "UP". And it still does helathchecks and status goes "down" if the backend is down.
> 
> What is wrong? The docs? Am I misinterpreting the docs? Bug?

Which version are yor running? healthCheckMode wil only be available
in 1.8.0, which is not released yet. See https://dnsdist.org/reference/config.html?highlight=newserver#newServer

	-Otto