Configuration Apache with mod_jk

Configurations:

/etc/cluster/cluster.conf:

        <rm log_level="7" central_processing="1">
                <failoverdomains>
                   <failoverdomain name="jboss_domain" ordered="1" restricted="1">
                      <failoverdomainnode name="axqad120-1" priority="1"/>
                      <failoverdomainnode name="axqad120-2" priority="1"/>
                   </failoverdomain>
                   <failoverdomain name="apache_domain" ordered="1" restricted="1">
                      <failoverdomainnode name="axqad120-3" priority="1"/>
                      <failoverdomainnode name="axqad120-4" priority="1"/>
                   </failoverdomain>
                </failoverdomains>
                <resources/>
                <service autostart="1" name="protixvip1" domain="apache_domain">
                   <ip address="192.168.10.240" monitor_link="1"/>
                   <apache name="protixapache"/>
                </service>
        </rm>

/etc/httpd/conf.d/mod_jk.conf:

    LoadModule jk_module modules/mod_jk.so

    JkWorkersFile /etc/httpd/conf.d/workers.properties
    JkShmFile /var/log/httpd/mod_jk.shm
    JkLogFile /var/log/httpd/mod_jk.log
    JkLogLevel info

    # Mount examples
    #JkMount /servlets-examples/* jkworker
    #JkMount /jsp-examples/* jkworker
    JkMount /ClusterWeb/* protixrouter

    # Enable the JK manager access from localhost only and local network for validation!
    <Location /jkmanager/>
       JkMount protixjkstatus
       Order deny,allow
       Deny from all
       Allow from 127.0.0.1
       Allow from 192.168.0.0/16
    </Location>

/etc/httpd/conf.d/workers.properties:

    # The advanced router LB worker and status checking for health checks of mod_jk servers.
    worker.list=protixrouter,protixjkstatus

    # Define the LB worker
    worker.protixrouter.type=lb
    worker.protixrouter.balance_workers=protixworker1,protixworker2

    # Define a 'jkstatus' worker using status
    worker.protixjkstatus.type=status

    # Define a worker using ajp13
    worker.protixworker1.port=8009
    worker.protixworker1.host=axqad120-1.cc.atix
    worker.protixworker1.route=axqad120-1
    worker.protixworker1.type=ajp13
    worker.protixworker1.lbfactor=1
    # Define preferred failover node for worker1
    #worker.protixworker1.redirect=worker2

    # Define another worker using ajp13
    worker.protixworker2.port=8009
    worker.protixworker2.host=axqad120-2.cc.atix
    worker.protixworker2.route=axqad120-2
    worker.protixworker2.type=ajp13
    worker.protixworker2.lbfactor=1
    # Disable worker2 for all requests except failover
    #worker.protixworker2.activation=disabled
    # Define preferred failover node for worker1
    #worker.protixworker2.redirect=worker1

Mod_jk loadbalancing:

The overall result is that workers managed by the same lb worker are load-balanced (based on their lbfactor and current user session) and also fall-backed so a single Tomcat process death will not "kill" the entire site.

Session stickiness

If you want to use session stickiness, you must set different jvmRoute attributes in the Engine element in Tomcat's server.xml. As we are using JBoss we need to keep track on session stickiness via JBoss !?. Furthermore the names of the workers which are managed by the balancer have to be equal to the jvmRoute of the Tomcat instance they connect with.