7.2.1 Using mod_jk

This configuration uses Apache mod jk plug-in to load balance JBoss cluster on AJP protocol. It provides support for the Apache JServ Protocol (AJP).

Perform following steps to configure:

  1. From the Apache Tomcat Connector site, download the mod_jk plug-in file for your operating system.
    Note: Ensure that your Apache server supports downloaded mod_jk plug-in file.

  2. Rename the downloaded file to mod_jk.so and save it in the APACHE_HOME/modules/ directory .

  3. In a text editor, open the httpd.conf file located in APACHE_HOME/conf and add the following line at the end of the file: Include conf/mod-jk.conf

  4. Create a new file APACHE_HOME/conf/mod-jk.conf with the following content : 

    # Load mod_jk module 
# Specify the filename of the mod_jk lib 
LoadModule jk_module modules/mod_jk.so 
# Where to find workers.properties 
JkWorkersFile conf/workers.properties 
# Where to put jk logs 
JkLogFile logs/mod_jk.log 
# Set the jk log level [debug/error/info] 
JkLogLevel info 
# Select the log format 
JkLogStampFormat "[%a %b %d %H:%M:%S %Y]" 
# JkOptions indicates to send SSK KEY SIZE 
JkOptions +ForwardKeySize +ForwardURICompat -ForwardDirectories 
# JkRequestLogFormat 
JkRequestLogFormat "%w %V %T" 
# Mount your applications 
JkMount /* loadbalancer 
# You can use external file for mount points. 
# It will be checked for updates each 60 seconds. 
# The format of the file is: /url=worker 
# /examples/*=loadbalancer 
#JkMountFile conf/uriworkermap.properties 
# Add shared memory. 
# This directive is present with 1.2.10 and 
# later versions of mod_jk, and is needed 
# for load balancing to work properly 
JkShmFile logs/jk.shm 
# Add jkstatus for managing run-time data 
<Location /jkstatus/> 
JkMount status 
Order deny,allow 
Deny from all 
Allow from 127.0.0.1 
</Location>
  5. Create a file at conf/workers.properties with following content 
    # for mapping requests 
worker.list=loadbalancer,status 
# Define Node1 
# modify the host as your host IP or DNS name. 
worker.node1.port=8009 
worker.node1.host=node1.mydomain.com 
worker.node1.type=ajp13 
worker.node1.lbfactor=1 
worker.node1.cachesize=10 
# Define Node2 
# modify the host as your host IP or DNS name. 
worker.node2.port=8009 
worker.node2.host= node2.mydomain.com 
worker.node2.type=ajp13 
worker.node2.lbfactor=1 
worker.node2.cachesize=10 
# Load-balancing behavior 
worker.loadbalancer.type=lb 
worker.loadbalancer.balance_workers=node1,node2 
worker.loadbalancer.sticky_session=1 
#worker.list=loadbalancer 
# Status worker for managing load balancer 
worker.status.type=status
  6. In the file, define following items:

    • Each node of the cluster (in this example, two nodes named node1 and node2)

    • Add all the nodes defined in the file to the worker.loadbalancer.balance_workers entry.

  7. For each node in the cluster, open the server.xml file located at [appserver root]/server/<profile_name>/deploy/jbossweb.sar for editing.

  8. Search the server.xml file for the Engine name element and add a jvmRoute attribute. For example, on a node named node1 should be: <Engine name="jboss.web" defaultHost="localhost" jvmRoute="node1">

  9. Save the edited server.xml file.
    Note: For each cluster node value of jvmRoute must be unique and match to the value of the worker that connects to the respective JBoss.

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