mod_jk Installation and Configuration
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What is Apache Tomcat?
Apache Tomcat is the servlet container that is used in the
official Reference Implementation for the Java Servlet and
JavaServer Pages technologies.
Apache Tomcat powers numerous large-scale,
mission-critical web applications across a diverse range of
industries and organizations
What is mod_jk?
mod_jk is a replacement to the elderly
mod_jserv. It is a completely new Tomcat-Apache plug-in that
handles the communication between Tomcat and Apache.
mod_jserv was too complex. Because it was ported from Apache/JServ,
it brought with it lots of JServ specific bits that aren't
needed by Apache.
mod_jserv supported only Apache. Tomcat supports many web
servers through a compatibility layer named the jk library.
Supporting two different modes of work became problematic in
terms of support, documentation and bug fixes. mod_jk should fix
The layered approach provided by the jk library makes it easier
to support both Apache1.3.x and Apache2.xx.
Better support for SSL. mod_jserv couldn't reliably identify
whether a request was made via HTTP or HTTPS. mod_jk can, using
the newer Ajpv13 protocol.
Apache2 Installation and Configuration
For apache2 Installation click
and we will see now some configuration
Edit /etc/apache2/apache2.conf. Change
DirectoryIndex index.html index.cgi index.pl index.php
DirectoryIndex index.html index.htm
index.shtml index.cgi index.php index.php3 index.pl index.xhtml
Edit /etc/mime.types and comment out the following lines:
#application/x-httpd-php phtml pht php#application/x-httpd-php-source
Edit /etc/apache2/mods-enabled/php4.conf and comment out the
# AddType application/x-httpd-php .php .phtml .php3
# AddType application/x-httpd-php-source .phps
Edit /etc/apache2/ports.conf and add Listen 443
Now we have to enable some Apache modules (SSL, rewrite and
Installing JDK in Debian
In order to run Tomcat, you will need to
install JDK and set the JAVA_HOME environment variable to
identify the location of the JDK environment on your system.
1. You can download JDK 5.0 at
2. Click on Download JDK 5.0 Update 6 to go to
the download page.
3. Click Accept to accept the license agreement.
4. Next choose the Linux self-extracting file. This is the
download for the self-extracting binary file rather than the
5. Download to your preferred download directory. Change to that
directory and make it executable by executing the following
#chmod +x jdk-1_5_0_06-linux-i586.bin
Now execute the file:
You should now have a new directory called jdk1.5.0_06. Now move
this directory to the location where it should be run. We chose
#mv jdk1.5.0_06 /usr/lib
Now create a symbolic link called jdk to JAVA_HOME by the
following command. This allows you to easily switch back and
forth between different jvms should you ever need to.
#ln -s jdk1.5.0_06 jdk
Now we need to set the JAVA_HOME environment variable. Add the
following at the end of /etc/profile just after export PATH.
/etc/profile is executed at startup and when a user logs into
the system. In order to update the environment you will need to
log out and log back in to the system.
Check to make sure JAVA_HOME is defined correctly by executing
the command below. This should report the location of the Java
SDK which should be /usr/lib/jdk.
Installing Tomcat in Debian Linux
In this section you will download and install Apache Tomcat
5.5.16. For this particular setup, there is no need to build the
package from source, we will download the binary version.
1. Download the binary version to your preferred download
directory from here:
http://tomcat.apache.org/download-55.cgi. Choose the tar.gz
from the core section for 5.5.16.
2. Now change to that directory and extract the files using the
#cd /downloads #(be sure to change to your download directory)
You should now have a new directory called apache-tomcat-5.5.16.
Now move this directory to the location where it should be
installed. Again, We chose /usr/lib/. Note that this location
will be referred to as CATALINA_HOME in the Tomcat
#mv apache-tomcat-5.5.16 /usr/lib
3. Next change to the /usr/lib/ directory.
4. Now create a symbolic link called apache-tomcat to the
CATALINA_HOME by the following command.
#ln -s apache-tomcat-5.5.16 apache-tomcat
This will save you from having to make changes to startup and
shutdown scripts each time you upgrade Tomcat and if you so
desire, it also allows you to keep several versions of Tomcat on
your system and easily switch amongst them.
You should now be able to start and stop Tomcat from the
CATALINA_HOME/bin directory. If you are using another shell
other than the bash shell you will nee to add sh to the
beginning of the command. You should now be able to test that
Tomcat is installed by starting it and opening your browser and
entering http://localhost:8080 into your browser. Port 8080 is
the default port for Tomcat and can be easily changed in the /usr/lib/apache-tomcat/conf/server.xml
file. (We will work with this file later on.) If you plan to
access this page remotely, be sure to forward the respective
port to your server's IP address within your router. You should
now see the Tomcat welcome page that contains links to Tomcat
documentation as well as sample JSP/Servlet scripts. Verify that
Tomcat is running by executing some of the examples found on the
To shutdown the server, you will need to execute the following
command. Feel free to try it, but for now we will leave Tomcat
Installing and configuring mod_jk
In order to make the connection between Tomcat and Apache, we
will need to download and install mod_jk connector. You will
find that the Apache documentation recommends that you install
the packaged version of mod_jk if it is available for your
particular Linux distribution. Many outdated resources recommend
installing the mod_jk2 connector, but we have found that it has
been deprecated and although mod_jk was developed before
mod_jk2, it is still fully supported and is very stable.
1. Download the current source from the Apache archives:
jakarta-tomcat-connectors-1.2.15-src.tar.gz file to your /usr/src/
2. Change to the /usr/src directory.
3. Next, extract the contents to create the /usr/src/jakarta-tomcat-connectors-1.2.15-src
4. Change to the /usr/src/jakarta-tomcat-connectors-1.2.15-src/jk/native
5. Now you are ready to create the custom configure file for
your system. Execute the following:
This will create a configure file in the /usr/src/jakarta-tomcat-connectors-1.2.15-src/jk/native
6. Execute the following command in order to configure mod_jk
for your system.
Important note: You will need to have apxs2 (APache eXtension
tool) installed and configured with Apache. If you do not have
it, as was my case, you can download and install the
apache2-threaded-dev package (which replaced the former
apache-dev package) from www.debian.org. At the time of this
writing, the Debian package archive at www.debian.org was down
and they referred me to their temporary site until they resolved
their issues pdo.debian.net. I found the apache2-threaded-dev
package and was able to install it successfully.
Be sure to include the correct location apxs2 on your system in
the path of the command.
7. Now build the mod_jk with the following:
8. Finally, if you were successful with the previous commands,
copy the newly created mod_jk.so to your Apache2 modules
directory. My modules were located at /usr/lib/apache2/modules.
You now are ready to move to the next stage which is to begin
configuring Apache and Tomcat. You can find more information
about the mod_jk connector here http://tomcat.apache.org/connectors-doc/howto/apache.html.
Configuring Tomcat and Apache
Create the workers.properties file.
Important note: Be sure to make a
backup copy of your config files before modifying.
The workers.properties file contains the details about how each
process is linked to Tomcat by defining workers that communicate
through the ajpv13 protocol. Refer to the Workers HowTo for more
1. First create the workers.properties file in your Apache2 root
2. Next, open the workers.properties file and add the following.
You can find many other examples of the workers.properties file
on the internet, but this is the one that I created and it seems
to work fine with the other portions that have already been
configured in this tutorial.
3. Save and close the file.
4. Now we need to open the /etc/apache2/apache2.conf file and
add the following lines at the bottom. (httpd.conf is just for
LoadModule jk_module /usr/lib/apache2/modules/mod_jk.so
# Where to find workers.properties
# Where to put jk
# Set the jk log level
# Select the log format
JkLogStampFormat "[%a %b %d %H:%M:%S %Y] "
# JkOptions indicate to send SSL KEY SIZE,
JkOptions +ForwardKeySize +ForwardURICompat -ForwardDirectories
# JkRequestLogFormat set the request format
JkRequestLogFormat "%w %V %T"
# Send servlet for context / jsp-examples to worker named
JkMount /jsp-examples worker1
# Send JSPs for context /jsp-examples/* to worker named worker1
JkMount /jsp-examples/* worker1
Save and close the file.Now a final security point.
We will create a group and user tomcat tomcat like that:
#useradd -g tomcat tomcat
Then change the user and group of the Tomcat path:
#chown -R tomcat:tomcat /usr/lib/apache-tomcat-5.5.16
To change the password of tomcat user, with root type:
and follow the instructions.
Then to start and stop the Tomcat server you should use the
#su - tomcat
Now stop and start Tomcat:
And restart Apache:
Testing Your Installation
In this test, we are directing all URLs that begin with "/jsp-examples"
In a real world situation, we might only direct JSPs or servlets
to the JK worker.
Make sure no other server is running on the default Tomcat ports
of 8005, 8009 and 8080.
Make sure no other server is running on the Apache port, which
is normally 8080 or 80.
Start Tomcat first: Always start Tomcat first and then start
If you have to bounce Tomcat, remember to take down Apache first
and restart it after Tomcat restarts.
Start Apache: Point your browser to http://localhost and verify
that you get the default Apache page. Substitute "localhost" for
the actual machine name/IP if necessary.
Point your browser to http://localhost:8080 and verify that you
get the default Tomcat page.
Point your browser to http://localhost/jsp-examples/ and verify
that you get the index page for the Tomcat examples.
This will be served by Apache and will indicate that you have
completed your integration of Apache and Tomcat successfully.
Important References and paths
Tomcat stop and start
Note:Some of you might have noticed
we are using unp package for extracting tar.gz file.Iy you want
to know how to install this check