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: [email protected] :: m: (416) 561-4871
www.thestar.com www.topscms.com
*From:* [email protected]
[mailto:[email protected]] *On Behalf Of *Mohan Rao
*Sent:* September-15-10 9:26 AM
*To:* [email protected]
*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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