Re: How to check backend servers thru Haproxy?

From: Guillaume Bourque <>
Date: Fri, 27 May 2011 08:27:51 -0400

Hi Willy,

should those two lines

       server srv1 cookie s1
       server srv2 cookie s2


       server srv1 <> cookie srv1
       server srv2 <> cookie srv2

Not sure but since I can't test right now i thought to ask the master ;-)


Yes you can do that using the "force-persist" statement. The principle
> is that you define with ACLs how to detect that an incoming request is
> in fact one of your tests. That could be an IP address, a user-agent,
> or a cookie for example. Many people like the cookie because you already
> need to force one for the persistence, so if you can force one, you can
> force a second one. When this rule is matched, then haproxy will send
> your request to the server associated with the persistence cookie,
> whatever its state, and will not redispatch the request in case of
> failure. This statement was created exactly for the need you describe
> here.
> So let's consider the following setup :
> listen pub
> bind :80
> cookie SRV
> server srv1 cookie s1
> server srv2 cookie s2
> acl its_me hdr_sub(cookie) TEST=true
> force-persist if its_me
> Then you configure your browser to send two cookies :
> SRV=srv1
> TEST=true
> and you send any request you want there. You'll always be sent
> to server1.
> Cheers,
> Willy

Guillaume Bourque, B.Sc.,
consultant, infrastructures technologiques libres
514 576-7638,
Received on 2011/05/27 14:27

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