Apache, Tomcat cluster, load balancing using mod_jk

Apache

The Apache HTTP Server Project is a collaborative software development effort aimed at creating a robust, commercial-grade, feature ful, and freely-available source code implementation of an HTTP (Web) server. The project is jointly managed by a group of volunteers located around the world, using the Internet and the Web to communicate, plan, and develop the server and its related documentation. This project is part of the Apache Software Foundation. In addition, hundreds of users have contributed ideas, code, and documentation to the project. This file is intended to briefly describe the history of the Apache HTTP Server and recognize the many contributors. 

Tomcat

Apache Tomcat is an open source software implementation of the Java Servlet and JavaServer Pages technologies. The Java Servlet and Java Server Pages specifications are developed under the Java Community Process.
Apache Tomcat is developed in an open and participatory environment and released under the Apache License version 2. Apache Tomcat is intended to be a collaboration of the best-of-breed developers from around the world. We invite you to participate in this open development project.

 Download the required software 

• Apache 2.x Binaries 
• Tomcat 6.x Binaries
• The JK module

Installing of Apache and Tomcat   please refer previous posting of installing of Apache and Tomcat

load the mod_jk.so module 

LoadModule jk_module modules/mod_jk.so

JkWorkersFile conf/workers.properties
JkLogFile logs/mod_jk.log
JkLogLevel info

below DOcument Root

JkMount /*.jsp loadbalancer
JkMount /servlet/* loadbalancer

And create worker.properties file in /etc/httpd/conf/ directory

#
# workers.properties 
#

# In Unix, we use forward slashes:
ps=/

# list the workers by name

worker.list=tomcat1, tomcat2, loadbalancer

# ------------------------
# First tomcat server
# ------------------------
worker.tomcat1.port=8019
worker.tomcat1.host=localhost
worker.tomcat1.type=ajp13

# Specify the size of the open connection cache.
#worker.tomcat1.cachesize

#
# Specifies the load balance factor when used with
# a load balancing worker.
# Note:
#  ----> lbfactor must be > 0
#  ----> Low lbfactor means less work done by the worker.
worker.tomcat1.lbfactor=100


# ------------------------
# Second tomcat server
# ------------------------
worker.tomcat2.port=8029
worker.tomcat2.host=localhost
worker.tomcat2.type=ajp13

# Specify the size of the open connection cache.
#worker.tomcat2.cachesize

#
# Specifies the load balance factor when used with
# a load balancing worker.
# Note:
#  ----> lbfactor must be > 0
#  ----> Low lbfactor means less work done by the worker.
worker.tomcat2.lbfactor=100


# ------------------------
# Load Balancer worker
# ------------------------

#
# The loadbalancer (type lb) worker performs weighted round-robin
# load balancing with sticky sessions.
# Note:
#  ----> If a worker dies, the load balancer will check its state
#        once in a while. Until then all work is redirected to peer
#        worker.
worker.loadbalancer.type=lb
worker.loadbalancer.balanced_workers=tomcat1, tomcat2

#
# END workers.properties
#
 

and goto the tomcat server1 and edit the file /opt/tomcat1/conf/server.xml

edit  line 

                                                   to

             to
     

and goto the tomcat server2 and edit the file /opt/tomcat2/conf/server.xml

to

 


  
             to
     

In  apache server

NameVirtualHost *


ServerName localhost1
JkMount /*.jsp tomcat1
JkMount /servlet/* tomcat1


ServerName localhost2
JkMount /*.jsp tomcat2
JkMount /servlet/* tomcat2
 

And save the files and restart the both tomcat1 and tomcat2 server and apache start

and in browser

http://localhost

apache index.html will dispaly

and http://localhost/index.jsp

request go to server1 and continue if will server load heavy

 it will redirect to server2 or in case of fail over