Varnish round-robin loadbalancing with Virtualhost (Namebased)

Fri Aug 30 14:55:37 CEST 2013

That is my requirement !!!.  i'm using the same IP address for both hosts,
and need to do the load-balancing between two servers. thats what i wanted
to know,  Actually i'm playing with different varnish configs :) on my
virtual box.,  thought to give this config a try....but that didnt work. it
is working perfectly with different IP's, or IP based Vhosts.
Thanks Thierry for the response.
cheers,
Tharanga

On Fri, Aug 30, 2013 at 10:46 PM, MAGNIEN, Thierry
<thierry.magnien at sfr.com>wrote:

> Hi,
>
> I think I understood the point :
> - you have 2 backends hosted under the same IP address : www.backend1.comand
> www.backend2.com
> - your varnish server gets requests (for example) for www.frontend.com
> - you want requests to be load-balanced between your 2 backends BUT this
> would need the bereq.host to be rewritten to either www.backend1.com or
> www.backend2.com
> - BUT you can't do this in your VCL because you don't know which backend
> will be selected.
>
> In fact, this would need the director to rewrite the host header once the
> real backend has been selected, which I don't think is possible.
>
> Anyway, I still wonder why the hell you need varnish for this, where a
> HAProxy would certainly do the trick ;-)
>
> Regards,
> Thierry
>
>
> De : varnish-misc-bounces+thierry.magnien=sfr.com at varnish-cache.org[mailto:
> varnish-misc-bounces+thierry.magnien=sfr.com at varnish-cache.org] De la
> part de Per Buer
> Envoyé : vendredi 30 août 2013 13:36
> À : Tharanga Abeyseela
> Cc : Varnish misc
> Objet : Re: Varnish round-robin loadbalancing with Virtualhost (Namebased)
>
> Hi Tharanga,
>
> You seem not to understand. Varnish will just pass the host header in the
> request to the backend you specify. Looking at the VCL you provided you put
> both the backends into one director. This is probably not what you want to
> do.
>
> Try removing the director. Name the directors xxx and yyy and have the VCL
> look like.
>
> sub vcl_recv {
>     if (req.http.host ~ "xxx.com") {
>         req.backend = xxx;
>     } else if (..
>
> }
> Also the next bit doesn't make sense:
> if (req.request)
>     {
>     return(pass);
>     }
>
> }
>
> On Fri, Aug 30, 2013 at 10:42 AM, Tharanga Abeyseela <
> tharanga.abeyseela at gmail.com> wrote:
> Hi,
>
> Actually i tried that link, still it is not working. it should work for a
> ip based virtual host, but namebased virtual host is not working.
> becuase main request coming to varnish/80 and varnish should redirect the
> traffic to the backend server based on my round-robin director. when you
> resolve dns for those two hosts (xxx.com and yyy.com) it reuturns the
> same IP. that is 192.168.0.100. But there should be a way to send the
> host-header to apache. Not sure how it works here. But when i use different
> server (192,168.0.200/ zzz.com) it works without any issue, it roundrobin
> the traffic. This is an issue with namebased virtualhost.
> varnish recevie the traffic (cluster.com is my  varnish server), then it
> use it vcl to redirect based on my round-robin setting. but how it can send
> the traffic to the correct virtualhost. because it gets only the same IP
> address from the DNS. I managed to change the default behaviour by
> forcefully setting the host-header as follows to my other
> virtualhost(yyy..com)
> set.req.host="yyy.com" ;
> then all request went to yyy.com instead of xxx.com. but what i want is
> a round-robin fashio...to send traffic. first req to xxx.com/ 2nd req to
> yyy.com and so on..
>
> I was trying to find some resourses on the net, stackoverflow etc..but no
> luck yet.
>
> Thanks again for your help
> Cheers,
> Tharanga
>
> On Fri, Aug 30, 2013 at 5:05 PM, Per Buer <perbu at varnish-software.com>
> wrote:
> Hi Tharanga,
>
> You seem to be a bit confused about how the directors and backends work in
> Varnish. Please read this:
>
>
> https://www.varnish-cache.org/docs/trunk/users-guide/vcl-backends.html#backends-and-virtual-hosts-in-varnish
>
> Note that the .host property of the backend has NOTHING to do with the
> virtual host.
>
> On Fri, Aug 30, 2013 at 2:02 AM, Tharanga Abeyseela <
> tharanga.abeyseela at gmail.com> wrote:
> Hi Per,
> Thanks for the reply. Actually my set up looks like this.
>
> cluster.com - 192.168.0.200 (varnish/port 80)
> xxx.com - 192.168.0.100  (apache,namebased vhost/8080 - backendname -
> website)
> yyy.com - 192.168.0.100  (apache,namebased vhost/8080 -backendname - api)
> cluster.com is the varnish server and front-end connections coming to
> this and rewrite to other defined back-ends (round-robin based balancing)
>
>
>
> backend website {
>     .host = "xxx.com";
>     .port = "8080";
>
> }
> backend api {
>     .host = "yyy.com";
>     .port = "8080";
>
> }
>
> director clust round-robin {
> { .backend = api;  }
> { .backend = website;  }
>
> }
>
> sub vcl_recv {
> set req.backend = clust;
> if (req.request)
>     {
>     return(pass);
>     }
>
> }
>
> when i hit the cluster.com , it is always going to xxx.com, but what i
> need to do is first request go to xxx.com second request yyy.com and so
> on...when i add another server (different host/different IP say
> 192.168.0.111/zzz.com, and a different backend) , it goes like this
> first request - xxx.com
> second request - xxxx.com
> third request - zzz.com
>
> but i can change the default behavior by setting up set req.host = yyy.comand then it will goes to
> first request - yyy.com
> second request - yyy.com
> third request - zzz.com
> this is something to do with the host-header forwarding to the correct
> back-end. how should i add that functionality to the vcl_recv ?
> appreciate your help on this, this is working perfectly with other servers
> (different servers, not with namebased vhosts)
> cheers,
> Tharanga
>
>
>
>
>
>
>
>
>
>
>
>
> On Thu, Aug 29, 2013 at 11:58 PM, Per Buer <perbu at varnish-software.com>
> wrote:
> Hi mate,
>
> On Thu, Aug 29, 2013 at 3:17 PM, Tharanga Abeyseela <
> tharanga.abeyseela at gmail.com> wrote:
> (..)
>
> But how should i send host-headers to varnish to redirect to the correct
> server, This is always going to xxx.com.
>
> You don't. :-)
>
> You need to dispatch the request to the right backend in vcl_recv and have
> the backend handle that host. You could start rewriting the host in
> vcl_recv, but I would advise against it.
>
> So, if you have two vhosts handled by "website" you just set that as the
> backend in vcl_recv.
>
> --
>
> Per Buer
> CTO | Varnish Software AS
> Phone: +47 958 39 117 | Skype: per.buer
> We Make Websites Fly!
>
> Winner of the Red Herring Top 100 Europe Award 2013
>
>
>
>
>
>
>
> --
>
> Per Buer
> CTO | Varnish Software AS
> Phone: +47 958 39 117 | Skype: per.buer
> We Make Websites Fly!
>
> Winner of the Red Herring Top 100 Europe Award 2013
>
>
>
>
>
>
>
> --
>
> Per Buer
> CTO | Varnish Software AS
> Phone: +47 958 39 117 | Skype: per.buer
> We Make Websites Fly!
>
> Winner of the Red Herring Top 100 Europe Award 2013
>
>
>
>
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