[squid-users] ICAP service adaptation with service sets

We are using Squid as an adaptation proxy, with a farm of ICAP RESPMOD servers running on a single host. Our (partial) configuration is thus:

   icap_enable on

   icap_service respmod_service1 respmod_precache 0 icap://<host>:<ip_1>/RESPMOD
   icap_service respmod_service2 respmod_precache 0 icap://<host>:<ip_2>/RESPMOD

   adaptation_service_set respmod_set respmod_service1 respmod_service2

   adaptation_access respmod_set allow all

We would like to add an additional service to our proxy, which our current RESPMOD server would route our requests to in specific cases. If I understand the configuration guide correctly (http://www.squid-cache.org/Doc/config/icap_service/), I need to make the following changes:

* Modify the RESPMOD server to inject an "X-Next-Services: new_respmod_service<n>" header to activate the new service, and inject an "X-Next-Services: " header to deactivate the new service.

* Modify the squid configuration thus:

   icap_enable on

   icap_service respmod_service1 respmod_precache 0 icap://<host>:<ip_1>/RESPMOD routing=1
   icap_service respmod_service2 respmod_precache 0 icap://<host>:<ip_2>/RESPMOD routing=1

   icap_service new_respmod_service1 respmod_precache 0 icap://<host>:<ip_3>/RESPMOD
   icap_service new_respmod_service2 respmod_precache 0 icap://<host>:<ip_4>/RESPMOD

   adaptation_service_set respmod_set respmod_service1 respmod_service2
   adaptation_service_set new_respmod_set new_respmod_service1 new_respmod_service2

   adaptation_access respmod_set allow all
   adaptation_access new_respmod_set allow all

Can you tell us whether this configuration is correct, and clarify the following:

* Does the RESPMOD server need to inject an "X-Next-Services: " header with no value to deactivate the new service, or will it be bypassed by default?

* Each service has a farm of server processes for failover in case of error, but it seems the "X-Next-Services: new_respmod_server<n>" header will route to a specific service, not a service set. Is there a way to route requests to a service set or, if not, to provide failover for the new service?

* We are using squid version 3.1.14, for which we cannot find the release notes (3.1.15 is the earliest version we found). Can you confirm that 3.1.14 supports service adaptation ?

Francis Fauteux
Software Engineer
Received on Fri Apr 20 2012 - 17:53:19 MDT