Yes, we do something similar here. Create a new "Service" directives, using "URL" directive to catch "host=host_1". It'll look something like this:
Service
    URL ".*host=host_1*"
    BackEnd
       Address host_1
       Port   80
    End
End

Make sure this Service is declared before your session cookie and round-robin Service directives.

Andreas Andersson wrote:

Hi!

I've been running pound to do simple load balancing/failover between 3
machines using round robin and session tracking via cookies. Now I have new
need. I need to be able to send an additional request parameter (ie
myPage.php?host=host_1) and have pound direct me to host_1 instead of the
one in the session (or instead of the next one in the case of no cookie).

Is that possible using pound?

Psedo code:
if host_parameter
  use host_parameter
else if session cookie
  use session cookie
else
  use default / round robin

Thanks