Hostnames in backend definition...

Hettwer, Marian mhettwer at
Fri Dec 16 14:11:49 CET 2011

On 15.12.11 01:26, "Poul-Henning Kamp" <phk at> wrote:

>In message <CB0E7D6E.1A1F7%mhettwer at>, "Hettwer, Marian"
>>>We have talked about having the health-probe do DNS lookups in the
>>>background, but there are some interesting cornercases that needs
>>>to be dealt with, for instance:  What happens when we suddenly get
>>>two IP#'s back, or when we get no ip numbers back.
>>But as you said, you had your talks about it, so I guess the decision is
>>settled for now.
>No, not really:  Absent a consistent proposal on how it should work,
>we have not changed anything yet.

Since I'm not a programmer, all I can say is, honor TTL in dns answers and
asked again after the TTL expired.
But you will correctly reply, that this is not an easy task.
So I'd better shut up now ;)

>Ideas are always welcome, but they need to be thought through and all
>the odd-ball cases considered if we are to adobt them.
>>I can understand this. On the other hand, even in your own datacenter
>>setup, one might need to change dns records. Restarting a service for
>>is just... Well... painful.
>You don't need to restart any service:  Just load your VCL again and
>switch to the newly loaded VCL and you won't see your service as much
>as blink.

Oh right. Of course. :)

>Varnish was built to do that kind of change on the fly, and we're
>proud of how well it works.

And you guys can be proud of varnish! I'm using it wherever it's
appropriate and honestly, varnish is probably the most interesting piece
of software I stumbled upon in my last 6 years as a professional
Just keep up the good job!


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