Nginx health checks

[Alexander Staubo]

On Tue, Jun 10, 2008 at 6:21 PM, Barry Abrahamson <barry at automattic.com> wrote:
> We have about 350 web servers behind Nginx so it is a semi-regular
> occurrence that one of them fails for some reason (usually hardware).  Pound
> has a dedicated health check thread, that would perform the health checks
> and then mark servers up/down as appropriate.

HAProxy also offers this kind of periodic health check. You can set it
up to request a specific URL by HTTP, and the intervals can be
regulated according to whether the server is down, up or in between.

It can stagger the checks to avoid spikes, and supports dependencies,
where a server is only considered up if another server is up.

HAProxy can also be configured to listen to a port in a special
"health" mode that simply returns "200 OK" to every connection. This
can be used with Nagios or other tools for monitoring.

Alexander.