Custom Apache-style logging for Java-based applications

You missed a backslash in line 10.

when HTTP_REQUEST {
  set http_request_time [clock clicks -milliseconds]
  set request_log_line "\
[HTTP::request_num],\
[IP::remote_addr],\
[HTTP::method],\
[HTTP::version],\
[HTTP::host],\
\"[HTTP::uri]\",\
\"[HTTP::header value Referer]\",\
\"[HTTP::header User-Agent]\",\
\"[HTTP::cookie value JSESSIONID]\",\
[SSL::cipher name],\
[SSL::cipher version],\
[SSL::cipher bits]"
}

when HTTP_RESPONSE {
  set http_response_time [ clock clicks -milliseconds ]
  log local0. "$request_log_line,\
[HTTP::status],\
[HTTP::payload length],\
[expr $http_response_time - $http_request_time]"
}

Another option is to send the log to a remote syslog changing this line

log local0. "$request_log_line,\

to

log  local0.info  "$request_log_line,\