Multiple instances of varnish

david raistrick drais at
Thu May 5 19:00:34 CEST 2011

On Thu, 5 May 2011, Mike Franon wrote:

> I am trying to see if there is a way with using a single instance
> 1)  Varnish using VCL to recognize that it is a bot
> 2)  If it is a bot request, varnish will then use a different backend.

Sure.  You don't need multiple varnishes for this.

Define your backend, create a rule that matches on the headers you're 
matching on, set the backend.

I don't have anything that matches on user agents (which is what I assume 
you're looking at on the F5), and I'm not going to look at the docs to 
find out how to match on them, but an example that does the same thing for 

sub vcl_recv {
         #send webservices to its own backend
         if (req.url ~ "^/ws/.*$") {
           set req.backend = default_81;

david raistrick
drais at   

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