Feature: Adaptation logging
Goal: Log ICAP and eCAP transaction details
Developer: AlexRousskov, Christos Tsantilas
More: v3.0 branch
HTTP transactions have access.log. ICAP and eCAP transactions need their own log. Also, HTTP transactions affected by adaptations may need to log adaptation-related details in access.log.
ICAP log uses logformat codes that make sense for an ICAP transaction. Header-related codes are applied to the HTTP header embedded in an ICAP server response, with the following caveats: For REQMOD, there is no HTTP response header unless the ICAP server performed request satisfaction. For RESPMOD, the HTTP request header is the header sent to the ICAP server. For OPTIONS, there are no HTTP headers.
In addition to old logformat codes, the following format codes are also available for ICAP logs:
<icap_A ICAP server IP address. Similar to <A. <icap_service_name ICAP service name from the icap_service option in Squid configuration file. icap_ru ICAP Request-URI. Similar to ru. icap_rm ICAP request method (REQMOD, RESPMOD, or OPTIONS). Similar to existing rm. >icap_size Bytes sent to the ICAP server (TCP payload only; i.e., what Squid writes to the socket). <icap_size Bytes received from the ICAP server (TCP payload only; i.e., what Squid reads from the socket). icap_tr Transaction response time (in milliseconds). The timer starts when the ICAP transaction is created and stops when the transaction is completed. Similar to tr. icap_tio Transaction I/O time (in milliseconds). The timer starts when the first ICAP request byte is scheduled for sending. The timers stops when the last byte of the ICAP response is received. icap_to Transaction outcome: ICAP_ERR* for all transaction errors, ICAP_OPT for OPTION transactions, ICAP_ECHO for 204 responses, ICAP_MOD for message modification, and ICAP_SAT for request satisfaction. Similar to Ss. icap_Hs ICAP response status code. Similar to Hs. >icap_h ICAP request header(s). Similar to >h. <icap_h ICAP response header(s). Similar to <h.Adaptation log fields include:
If ICAP is enabled, the following two codes become available for access.log:
icap_total_time Total ICAP processing time for the HTTP transaction. The timer ticks when ICAP ACLs are checked and when ICAP transaction is in progress. <icap_last_h The header of the last ICAP response related to the HTTP transaction. Like <h, accepts an optional header name argument. Will not change semantics when multiple ICAP transactions per HTTP transaction are supported. adaptation_xact_times A comma-separated list of individual related adaptation transactions response times, in milliseconds. The order is to be defined during implementation.
Please see squid.conf.documented for more details.
Most of the features described here are unofficially available for Squid v3.0 as a Launchpad branch. Adaptation logging features are committed to Squid and scheduled for v220.127.116.11 release.