An apache log format that allow access logs (but not error logs) to be output in JSON format. I found this here: http://untergeek.com/2012/10/11/getting-apache-to-output-json-for-logstash/ -- but modified it for my purposes a good bit.

apache-json-log-format

# Access Logs
LogFormat "{ \
            \"@vips\":[\"%v\"], \
            \"@source\":\"%v%U%q\", \
            \"@source_host\": \"%v\", \
            \"@source_path\": \"%f\", \
            \"@tags\":[\"Apache\",\"Access\"], \
            \"@message\": \"%h %l %u %t \\\"%r\\\" %>s %b\", \
            \"@fields\": { \
                \"timestamp\": \"%{%Y-%m-%dT%H:%M:%S%z}t\", \
                \"clientip\": \"%a\", \
                \"duration\": %D, \
                \"status\": %>s, \
                \"request\": \"%U%q\", \
                \"urlpath\": \"%U\", \
                \"urlquery\": \"%q\", \
                \"method\": \"%m\", \
                \"referer\": \"%{Referer}i\", \
                \"user-agent\": \"%{User-agent}i\", \
                \"bytes\": %B \
                }  \
           }" ls_apache_json
 
 
# The catch-all
CustomLog "||/usr/local/bin/udpclient.pl 127.0.0.1 5001" ls_apache_json