I have used Tomcat + Apache for a while - yet I have never had to do the installation myself. Recently I needed an R&D server for the Jira Services I'm developing; enter mod_jk installation. This post is for anyone that wants to install mod_jk - the right way - and avoid the nightmare documentation that currently exists.

1. netstat to make sure you select unused ports e.g.    
         
   1. 8080: Apache
         
   2. 8081: Tomcat
         
   3. 8009: mod_jk
      
2. install Tomcat; verify http connection
3. install Apache; verify http connection
4. install mod_jk (mod_jk2 is deprecated)
5. create $CATALINA_HOME/conf/workers2.conf    

   # configure shared memory
   file = /opt/tomcat5/logs/shm.file
   size = 1048576
   # configure tomcat worker
   worker.list = mod_jk_worker
   worker.mod_jk_worker.type = ajp13
   worker.mod_jk_worker.host = localhost
   worker.mod_jk_worker.port = 8009
   # channel only used in Windows
   worker.mod_jk_worker.channel = myTomcat

6. modify $APACHE_HOME/conf/httpd.conf    

   LoadModule jk_module modules/mod_jk.so
   <IfModule mod_jk.c>
     JkWorkersFile /etc/apache2/conf/workers2.conf
     JkLogFile /var/log/apache2/mod_jk.log
     JkLogLevel debug
     JkLogStampFormat "[%a %b %d %H:%M:%S %Y] "
     JkRequestLogFormat "%w %V %T"
     JkMount /jira mod_jk_worker
     JkMount /jira/* mod_jk_worker
   </IfModule>