Skip to content

Load Balancer Configuration

This section gives two examples of load balancer configuration, Apache web server (httpd) and HAProxy. These sample configuration files are meant only as examples for testing.

Apache HTTP Server Example

The following changes configure the Apache HTTP server (httpd) as a load balancer.

  1. Add following line to the end of the httpd.conf file:

    Include conf/mod-jk.conf

  2. Create the following two files in the /conf folder of your httpd server.

  3. mod-jk.conf:

    # 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
# for load balancing to work properly
JkShmFile logs/jk.shm
#JkShmFile /var/log/httpd/mod_jk.shm

# Add jkstatus for managing runtime data
<Location /jkstatus>
 JkMount status
 Order deny,allow

 Allow from all
</Location>
    • workers.properties:
# Define list of workers that will be used
# 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=123.45.6.701
worker.node1.type=ajp13
worker.node1.lbfactor=1

# Define Node2
# modify the host as your host IP or DNS name.
worker.node2.port=8009
worker.node2.host=123.45.6.702
worker.node2.type=ajp13
worker.node2.lbfactor=1

# Load-balancing behaviour
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

HAProxy Load Balancer Example

The following example is a configuration for the HAProxy load balancer. HAProxy is a high-performance, free and open source load balancer for Linux/x86 and Solaris/Sparc.

Edit the /etc/haproxy.cfg file as follows:

global
        log         127.0.0.1 local2 debug #log using syslog service on localhost
        maxconn     4096 # Total Max Connections. This is dependent on ulimit
        daemon

defaults
        mode        http
        maxconn     4096
        clitimeout  60000
        srvtimeout  30000
        contimeout  4000
        option      httpclose # Disable Keepalive
        log         global
        option      httplog

listen  farm 123.45.6.700:80
        mode http
        stats uri /haproxy #show haproxy colsole
        balance roundrobin
        cookie farmID insert #assign a farmID coockie to each client
        option httpclose
        option httpchk
        option forwardfor

        ## Define your servers to balance
        server node1 123.45.6.701:8081 cookie farmID_node1 check
        server node2 123.45.6.702:8081 cookie farmID_node2 check

Troubleshooting

In some cases, when you are using a proxy or load balancer, your users may have problems with loading links and other resource files in hypermedia documents. This can occur when JasperReports Server generates links to a specific node instead of the host server.

For example, suppose you have a setup with a proxy host and two servers as follows:
proxy_host http://bi.example.com
node 1 http://node1:8080/jasperserver-pro
node 2 http://node2:8080/jasperserver-pro

When the user accesses http://bi.example.com, JasperReports Server forwards the user to the login page on the first available node, http://node1:8080/jasperserver-pro. After login, when the user accesses hypermedia, JasperReports Server generates links to hypermedia resources using the base http://node1:8080/jasperserver-pro instead of http://bi.example.com.

To resolve this, set the following in the /WEB-INF/js.config.properties file on all nodes:

deploy.base.url=http://bi.example.com