vcl_recv vcl_pipe vcl_pass vcl_hash vcl_purge vcl_miss vcl_hit vcl_deliver vcl_synth vcl_backend_fetch vcl_backend_response vcl_backend_error vcl_init vcl_fini if else elif elsif elseif call set unset new rollback synthetic esi include panic hash_data regsub regsuball ban abandon deliver error fetch hash hit_for_pass lookup ok pass pipe purge restart retry synth random client hash round-robin dns fallback std example abtest threescale authentication boltsort crashhandler curl digest dns header memcached null querystring shield softpurge statsd throttle timeutils urlcode var timers directors