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Previously I successfully get the jboss to run behind apache using the mod_jk module. Recently I have to deal with similar issue, only this time is configure the tomcat to run behind apache 2.2.

The Ubuntu-supplied Tomcat doesn’t listen for for AJP1.3 requests on port 8009 by default, so edit /var/lib/tomcat6/conf/server.xml, search for “8009″ and uncomment the AJP1.3 connector module:

/var/lib/tomcat6/conf/server.xml
…

…
Restart Tomcat, giving it time to start the listeners, and check that it is listening on port 8009:

$ sudo /etc/init.d/tomcat6 restart
 * Stopping Tomcat servlet engine tomcat6                                [ OK ]
 * Starting Tomcat servlet engine tomcat6                                [ OK ]
$ sudo netstat -ln | grep :8009
tcp6       0      0 :::8009                 :::*                    LISTEN     

For Lucid, restart Tomcat with $ sudo service tomcat6 restart.

If the listener is listening, Tomcat should be good to go.

Setting up Apache

To get Apache to talk to Tomcat, the first step is to install the AJP1.3 connector module mod_jk:

$ sudo apt-get install libapache2-mod-jk2

For Lucid, package is libapache2-mod-jk.

With the default Ubuntu packaging, this is all set up and should be loaded without any further intervention. The key to this is that /etc/apache2.conf includes all modules listed in /etc/apache2/mods-enabled. There’s no need to add the LoadModule directive to apache2.conf as you might see quoted in some places.

Then it’s just a matter of configuring Apache to route some requests through to Tomcat.

The core of the Apache configuration looks like this on a default Ubuntu setup:

JkWorkersFile /etc/apache2/workers.properties
JkShmFile     /var/log/apache2/mod_jk.shm
JkLogFile     /var/log/apache2/mod_jk.log
JkLogLevel    error
JkLogStampFormat "[%a %b %d %H:%M:%S %Y] "
JkMount /MyWebApplication/* tomcat

You have a choice at this point. You can configure this within the default virtual host that Ubuntu’s Apache comes with, or globally.

If you want to configure just for the virtual host, add the above section to the bottom of /etc/apache2/sites-available/default.

If you want to configure the forwarding globally, add the above section to the bottom of /etc/apache2/apache2.conf. In this case, you also need to add an extra line to the sites-available file to get the virtual site to read the mounts. Immediately under DocumentRoot is a reasonable place.

/etc/apache2/sites-available/default

...
DocumentRoot  /var/www
JkMountCopy   On
...

The final part of the jigsaw is to set up the worker.properties file now referred to in the Apache config files. So make a new file …

$ sudo touch /etc/apache2/workers.properties

… and edit it. With sudo of course

/etc/apache2/workers.properties

worker.list=tomcat

worker.tomcat.type=ajp13
worker.tomcat.host=localhost
worker.tomcat.port=8009

Look back at the lines we added to the Apache config files and note that the JkMount directives refer Apache to entries in workers.properties. If you had multiple Tomcat servers, you could achieve some simple application-level load balancing by routing different applications to different servers:

/etc/apache2/workers.properties

worker.list=tomcat_a, tomcat_b

worker.tomcat_a.type=ajp13
worker.tomcat_a.host=hosta
worker.tomcat_a.port=8009

worker.tomcat_b.type=ajp13
worker.tomcat_b.host=hostb
worker.tomcat_b.port=8009

Anyway, I digress. Restart Apache and you should be up and running.

$ sudo /etc/init.d/apache2 restart