[dnsdist] setAuto() healthchecks

[Thib D]

Hello Remi,

I think the issue here is that when you issue setAuto() on a backend,
> dnsdist will use the previous known state until the next health check


Exactly, it means that it could show a wrong state for a second (IIRC
because the healthchecks are set to run every second )

This looks wrong to me, and I just opened a PR [1] that sets the backend
> state to down when a setAuto() is issued. It means the backend will stay
> down until the next heath check, as it does when it is first added.
> Let me know if it solves your issue or if I didn't understand it correctly.


In this case, this would be solving our issue.

But does it means you would be considering a server as "down"  everytime
you use setAuto() ? What if the server is actually up ?

Thanks for your answer and for opening the PR,

Best regards.

Thibaud D.




2017-08-17 16:19 GMT+02:00 Remi Gacogne <remi.gacogne at powerdns.com>:

> Hello Thibaud,
>
> On 08/17/2017 11:22 AM, Thib D wrote:
> > When you setDown() a server for 10 seconds and then setAuto() , it
> > returns the value of the last healthcheck before the setDown() happened,
> > no matter what happened during these 10 seconds.
> > In our case : our DNS server needs around 10 seconds to be up again. But
> > dnsdist returns a "up" value on the first second, even if the server is
> > still down.
>
> I think the issue here is that when you issue setAuto() on a backend,
> dnsdist will use the previous known state until the next health check.
> This looks wrong to me, and I just opened a PR [1] that sets the backend
> state to down when a setAuto() is issued. It means the backend will stay
> down until the next heath check, as it does when it is first added.
>
> Let me know if it solves your issue or if I didn't understand it correctly.
>
> [1]: https://github.com/PowerDNS/pdns/pull/5623
>
> Best regards,
> --
> Remi Gacogne
> PowerDNS.COM BV - https://www.powerdns.com/
>
>
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>
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