Probing to see if Varnish is Alive.

[Richard Chiswell]

  I've got our load balancer requesting a MySQL driven PHP page via 
Apache and via Varnish.

Every second, our load balancer probes a page on our site. This page is 
set to "pass" through Varnish to Apache which then asks PHP to check 
MySQL. If all is ok, the page returns the text "All checks passed" - if 
that text isn't there within 0.5s (for example, Varnish is unavailable, 
Apache is unavailable, MySQL is unavailable etc), then that server is 
removed from our load balanced pool. If we do maintenance, we just kill 
Varnish (our site is still accessible to ourselves via port 8080 which 
the Apache port), bring Varnish back up and then wait a couple of 
seconds for the load balancer to notice the "All checks passed" text is 
being returned.

Rich

On 15/09/2010 15:55, Caunter, Stefan wrote:
>
> If your load balancer can do a port 80 check (or whatever port you are 
> using), you can block port 80 with pf to stop traffic flow, do your 
> updating, and return it to service by unblocking the port.
>
> Stefan Caunter :: Senior Systems Administrator :: TOPS
>
> e: scaunter at topscms.com  ::  m: (416) 561-4871
>
> www.thestar.com www.topscms.com
>
> *From:* varnish-misc-bounces at varnish-cache.org 
> [mailto:varnish-misc-bounces at varnish-cache.org] *On Behalf Of *Mohan Rao
> *Sent:* September-15-10 9:26 AM
> *To:* varnish-misc at varnish-cache.org
> *Subject:* Probing to see if Varnish is Alive.
>
> Hi,
>
> Is there a way to probe a varnish server to see if it is alive ? We 
> have a couple of varnish servers that are load balanced. We would like 
> the load balancer to stop sending traffic to a particular varnish 
> server if we are updating that server. Is there a recommended way to 
> do this ?
>
> Thanks & Regards,
>
> Mohan
>
>
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> varnish-misc at varnish-cache.org
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