Multiple Jboss Instances on one server

This works for JBOSS 4.0.5.GA! hopefully, it will work on some other versions. The important thing is to change the port number for the services you are running in your application – http, rmi, jndi, Webservice e.t.c. You will find these in the following xml files -All xml are in the server directory JBOSS.

Leave the first instance of your JBoss unchanged. In the 2nd instance, for example, update the xml files as described below:

…<jboss folder>…/server/default/deploy/jbossweb-tomcat55.sar/server.xml:
update 8080 to 18080

…<jboss folder>…/server/default/conf/jboss-service.xml:
update 1099 to 11099
update 1098 to 11098
update 4445 to 14445
update 4444 to 14444

…<jboss folder>…/server/default/conf/jboss-minimal.xml:
update 1099 to 11099
update 1098 to 11098
…<jboss folder>…/server/default/deploy/jms/uil2-service.xml – update 8093 to 18093

…<jboss folder>…/server/default/conf/jboss-service.xml – update 8083 to 18083

Link Apache to Jboss with mod_jk

Using Mod_jk 1.2 with JBoss

Using mod_jk 1.2.x with JBoss/Tomcat bundle and Apache2

Quick Overview

  1. Download Apache2
  2. Download modjk 1.2.x
  3. Change the main Apache config to include modjk config
  4. Create the modjk config
  5. Configure the modjk workers (which JBoss/Tomcat nodes Apache uses)
  6. Configure the Apache URIs served by modjk (the applications served by JBoss/Tomcat)
  7. Restart Apache
  8. Configure Tomcat (Give each JBoss/Tomcat a jvmRoute for session stickness)
  9. Restart JBoss
  10. Test it

More Details

This wiki outlines the various steps required to install a basic load-balancing solution based on JBoss/Tomcat and mod_jk 1.2.

Step #1: Download Apache2 Web Server
Get the latest Apache2 package from Apache.org and install it. We require no special configuration, just use the default settings. In the following steps, APACHE_HOME will represent the Apache install directory.

Step #2: Download mod_jk 1.2.x
Download the latest package available from Tomcats’s ‘Download Tomcat connector section’ page . Always download the latest stable release if possible.
Rename the lib mod_jk.so and drop it in APACHE_HOME/modules directory.
NOTE: Don’t use any release prior to mod_jk 1.2.15. Earlier releases are fairly buggy.

Note: Darwin Ports supports the installation of mod_jk on OS X. See http://darwinports.opendarwin.org/ for more info.

Step #3: Setup Apache to use modjk
Add this line at the very bottom in APACHE_HOME/conf/httpd.conf :

# Include mod_jk configuration file
Include conf/mod-jk.conf

Step #4: Create the modjk config
Under APACHE_HOME/conf, create mod-jk.conf and populate it as follows:

# 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
# Note: Changed from +ForwardURICompat.
# See http://tomcat.apache.org/security-jk.html
JkOptions +ForwardKeySize +ForwardURICompatUnparsed -ForwardDirectories

# JkRequestLogFormat
JkRequestLogFormat "%w %V %T"

# Mount your applications
JkMount /__application__/* 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
# Note: Replaced JkShmFile logs/jk.shm due to SELinux issues. Refer to
# https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=225452
JkShmFile run/jk.shm

# Add jkstatus for managing runtime data
<Location /jkstatus/>
JkMount status
Order deny,allow
Deny from all
Allow from 127.0.0.1
</Location>

mod_jk is ready to forward requests to JBoss instances. We need now to setup the workers

Step #5: Configuring workers
Under APACHE_HOME/conf, create workers.properties and populate it as follows:

# Define list of workers that will be used
# for mapping requests
# The configuration directives are valid
# for the mod_jk version 1.2.18 and later
#
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.connection_pool_size=10 (1)

# 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.node1.connection_pool_size=10 (1)

# Load-balancing behaviour
worker.loadbalancer.type=lb
worker.loadbalancer.balance_workers=node1,node2

# Status worker for managing load balancer
worker.status.type=status

Important: Please review http://tomcat.apache.org/connectors-doc/reference/workers.html for the directive descriptions. Especially lookout for the comments on cachsize for Apache 1.3.x.

(1) You should only set the connection_pool_size if the number of allowed connection to the Httpd is higher than maxThreads in server.xml

If you specify worker.loadbalancer.sticky_session=Off, each request will be load balanced between node1 and node2. But when a user opens a Session on one server, it is a good idea to always forward this user’s requests to the same server. Otherwise the user’s session data would need to be synchronized between both servers. This is called a “sticky session”, as the client is always using the same server he reached on his first request. Session stickiness is enabled by default.

Side Note: a non-loadbalanced setup with a single node required the “worker.list=node1” entry before mod_jk would function correctly. Without this setting I would only get a 500 error and no other useful messages in log or otherwise. -Harlequin516

Side Note: I tried both loadbalanced and single node methods on Fedora 4. Both setups causing jk.shm errno=13 and jk-runtime-status errno=13 in the mod_jk.log. Could only get 500 errors. As a last resort disabled selinux on apache server. Restarted service and connection was made first try. -paulbrown

Step #6: Create the URI to worker map file
Create a uriworkermap.properties file in the APACHE_HOME/conf directory. This file should contain the URL mappings you want Apache to forward to Tomcat. The format of the file is /url=worker_name. To get things started, paste this example into the file you created:

# Simple worker configuration file
#

# Mount the Servlet context to the ajp13 worker
/jmx-console=loadbalancer
/jmx-console/*=loadbalancer
/web-console=loadbalancer
/web-console/*=loadbalancer

This will configure mod_jk to forward requests to /jmx-console and /web-console to Tomcat. Step #7: Restart Apache
Step #8: Configure Tomcat
To complete the configuration, we also need to name each node accordingly to the names specified in workers.properties.
Edit JBOSS_HOME/server/all/deploy/jbossweb-tomcat50.sar/server.xml (replace /all with your own server name)
Locate the <Engine….> element and add an attribute jvmRoute:

<Engine name="jboss.web" defaultHost="localhost" jvmRoute="node1">
.
</Engine>

The jvmRoute attribute must match the name specified in workers.properties. In the server.xml file, make sure that the AJP 1.3 Connector is uncommented, e.g.:

<!-- A AJP 1.3 Connector on port 8009 -->
<Connector port="8009" address="${jboss.bind.address}"
      emptySessionPath="true" enableLookups="false" redirectPort="8443"
      protocol="AJP/1.3"/>

If you are only accepting requests via mod_jk, you can comment out the regular HTTP Connector; Tomcat then won’t listen on port 8080.

Step #9: Activate the UseJK Valve in JBoss (not needed with Tomcat Standalone)
Finally, we need to tell Tomcat to add the jvmRoute value to its session cookies so that mod_jk can route incoming requests.
Edit JBOSS_HOME/server/all/deploy/jbossweb-tomcat50.sar/META-INF/jboss-service.xml (replace /all with your own server name)
Locate the <attribute> element with a name of UseJK, and set its value to “true”:

<attribute name="UseJK">true</attribute>

Note that tomcat version can be 50 or 55 depending on the AS that you use. Step #10: Restart JBoss AS.

Step #11: Access the JBoss AS web-console through Apache by browsing to http://localhost/web-console and you should see the JBoss web console page.


Note: to use mod_jk with Jboss 2 (e.g. jboss 2.4.6), you must edit jboss.jcml. Add the ‘jvmRoute=<<myWorker>>’ to the Engine element under the EmbeddedCatalinaSX? mbean.