Tomcat 6 with JDK 6

This post will cover installation and configuration of Tomcat 6 with JDK 6 on CentOS, RHEL, Fedora, and OEL.

We will also show how to run Tomcat as a service, create a start/stop script, and configure Tomcat to run under a non-root user.

We will also look at configuring Tomcat Manager access and setting JAVA_OPTS.

This post has been updated for Tomcat 6.0.35. If you are using a newer release, simply update the file names below.

If you do not already have the Java Development Kit (JDK) installed on your machine, you will need to download and install the required JDK for your platform.

If you do have the JDK installed, you can skip to: Step 2: Download and Install the Tomcat 6.0.34 (or latest):

Step 1: Install the JDK

You can download the JDK here:  http://www.oracle.com/technetwork/java/javase/downloads/index.html

I’m using the latest, which is JDK 6, update 34. The JDK is specific to 32 and 64 bit versions.

My CentOS box is 64 bit, so I’ll need: jdk-6u34-linux-x64.bin.

If you are on 32 bit, you’ll need: jdk-6u34-linux-i586.bin

Download the appropriate JDK and save it to the /opt directory.

Now, create a new directory /usr/java.

[root@blanche ~]# mkdir /usr/java

Change to the /usr/java directory we created and install the JDK using ‘sh /opt/jdk-6u34-linux-x64.bin’

[root@blanche ~]# cd /usr/java
[root@blanche java]# sh /opt/jdk-6u34-linux-x64.bin

Set the JAVA_HOME path. This is where we installed our JDK above.

To set it for your current session, you can issue the following from the CLI:

[root@blanche java]# JAVA_HOME=/usr/java/jdk1.6.0_34
[root@blanche java]# export JAVA_HOME
[root@blanche java]# PATH=$JAVA_HOME/bin:$PATH
[root@blanche java]# export PATH

To set the JAVA_HOME for users, we add below to the user ~/.bashrc or ~/.bash_profile of the user. We can also add it /etc/profile and then source it to give to all users.

JAVA_HOME=/usr/java/jdk1.6.0_34
export JAVA_HOME
PATH=$JAVA_HOME/bin:$PATH
export PATH

Once you have added the above to ~/.bash_profile or ~/.bashrc, you should log out, then log back in and check that the JAVA_HOME is set correctly.

[root@blanche ~]# echo $JAVA_HOME
/usr/java/jdk1.6.0_34

Step 2: Download and Install Tomcat 6.0.35 (or latest):

Download apache-tomcat-6.0.35.tar.gz (or latest) here:  http://tomcat.apache.org/download-60.cgi

Save the file to a directory. I’m saving it to /root/apache-tomcat-6.0.35.tar.gz

Before proceeding, you should verify the MD5 Checksum for your Tomcat download (or any other download).

Since we saved the Tomcat download to /root/apache-tomcat-6.0.35.tar.gz, we’ll go to the /root directory and use the md5sum command.

[root@blanche ~]# md5sum apache-tomcat-6.0.35.tar.gz
171d255cd60894b29a41684ce0ff93a8 *apache-tomcat-6.0.35.tar.gz

There is a link to display the MD5 checksum located just to the right off the download link.

Compare the output above to the MD5 Checksum provided and insure that they match exactly.

Now, move (mv) or copy (cp) the file to the /usr/share directory:

[root@blanche ~]# mv apache-tomcat-6.0.35.tar.gz /usr/share/apache-tomcat-6.0.35.tar.gz

Change to the /usr/share directory and unpack the file using tar -xzf:

[root@blanche ~]# cd /usr/share
[root@sv2 blanche ]# tar -xzf apache-tomcat-6.0.35.tar.gz

This will create the directory /usr/share/apache-tomcat-6.0.35

At this point, you could start Tomcat via the Tomcat bin directory using the Tomcat startup.sh script located at /usr/share/apache-tomcat-6.0.35/bin.

[root@blanche share]# cd /usr/share/apache-tomcat-6.0.35/bin
[root@blanche bin]# ./startup.sh

Step 3: How to Run Tomcat as a Service.

We will now see how to run Tomcat as a service and create a simple Start/Stop/Restart script, as well as to start Tomcat at boot.

Change to the /etc/init.d directory and create a script called ‘tomcat’ as shown below.

[root@blanche share]# cd /etc/init.d
[root@blanche init.d]# vi tomcat

And here is the contents of our script below:

#!/bin/bash
# description: Tomcat Start Stop Restart
# processname: tomcat
# chkconfig: 234 20 80
JAVA_HOME=/usr/java/jdk1.6.0_34
export JAVA_HOME
PATH=$JAVA_HOME/bin:$PATH
export PATH
CATALINA_HOME=/usr/share/apache-tomcat-6.0.35

case $1 in
start)
sh $CATALINA_HOME/bin/startup.sh
;;
stop)
sh $CATALINA_HOME/bin/shutdown.sh
;;
restart)
sh $CATALINA_HOME/bin/shutdown.sh
sh $CATALINA_HOME/bin/startup.sh
;;
esac
exit 0

The above script is simple and contains all of the basic elements you will need to get going.

As you can see, we are simply calling the startup.sh and shutdown.sh scripts located in the Tomcat bin directory (/usr/share/apache-tomcat-6.0.35/bin).

You can adjust your script according to your needs and, in subsequent posts, we’ll look at additional examples.

CATALINA_HOME is the Tomcat home directory (/usr/share/apache-tomcat-6.0.35)

Now, set the permissions for your script to make it executable:

[root@blanche init.d]# chmod 755 tomcat

We now use the chkconfig utility to have Tomcat start at boot time. In my script above, I am using chkconfig: 244 20 80. 2445 are the run levels and 20 and 80 are the stop and start priorities respectively. You can adjust as needed.

[root@blanche init.d]# chkconfig --add tomcat
[root@blanche init.d]# chkconfig --level 234 tomcat on

Verify it:

[root@blanche init.d]# chkconfig --list tomcat
tomcat 0:off 1:off 2:on 3:on 4:on 5:off 6:off

Now, let’s test our script.

Start Tomcat:

[root@blanche ~]# service tomcat start
Using CATALINA_BASE: /usr/share/apache-tomcat-6.0.35
Using CATALINA_HOME: /usr/share/apache-tomcat-6.0.35
Using CATALINA_TMPDIR: /usr/share/apache-tomcat-6.0.35/temp
Using JRE_HOME: /usr/java/jdk1.6.0_34
Using CLASSPATH: /usr/share/apache-tomcat-6.0.35/bin/bootstrap.jar

Stop Tomcat:

[root@blanche ~]# service tomcat stop
Using CATALINA_BASE: /usr/share/apache-tomcat-6.0.35
Using CATALINA_HOME: /usr/share/apache-tomcat-6.0.35
Using CATALINA_TMPDIR: /usr/share/apache-tomcat-6.0.35/temp
Using JRE_HOME: /usr/java/jdk1.6.0_34
Using CLASSPATH: /usr/share/apache-tomcat-6.0.35/bin/bootstrap.jar

Restarting Tomcat (Must be started first):

[root@blanche ~]# service tomcat restart
Using CATALINA_BASE: /usr/share/apache-tomcat-6.0.35
Using CATALINA_HOME: /usr/share/apache-tomcat-6.0.35
Using CATALINA_TMPDIR: /usr/share/apache-tomcat-6.0.35/temp
Using JRE_HOME: /usr/java/jdk1.6.0_34
Using CLASSPATH: /usr/share/apache-tomcat-6.0.35/bin/bootstrap.jar
Using CATALINA_BASE: /usr/share/apache-tomcat-6.0.35
Using CATALINA_HOME: /usr/share/apache-tomcat-6.0.35
Using CATALINA_TMPDIR: /usr/share/apache-tomcat-6.0.35/temp
Using JRE_HOME: /usr/java/jdk1.6.0_34
Using CLASSPATH: /usr/share/apache-tomcat-6.0.35/bin/bootstrap.jar

We should review the Catalina.out log located at /usr/share/apache-tomcat-6.0.35/logs/catalina.out and check for any errors.

[root@blanche init.d]# less /usr/share/apache-tomcat-6.0.35/logs/catalina.out

We can now access the Tomcat Manager page at:

http://yourdomain.com:8080 or http://yourIPaddress:8080 and we should see the Tomcat home page.

Step 4 : Set JAVA_OPTS

Getting the right heap memory settings for your installation will depend on a number of factors.

For simplicity, we will set our inital heap size, Xms, and our maximum heap size, Xmx, to the same value of 128 Mb

You will want to set the JAVA_OPTS for PermSize as well as heap. If you don’t set PermSize you will get out of memory errors with most of the report servers covered on this site.

There are several approaches you can take as to where and how you set your JAVA_OPTS

Again, for simplicity, we will add our JAVA_OPTS memory parameters in our Catalina.sh file.

So, open the Catalina.sh file located under /usr/share/apache-tomcat-6.0.32/bin with a text editor or vi.

Since we are using 128 Mb for both initial and maximum heap size, add the following line to Catalina.sh


JAVA_OPTS="-Xms128m -Xmx128m -XX:PermSize=128M -XX:MaxPermSize=128M"

So now the top of your Catalina.sh will look as below.


#!/bin/sh
JAVA_OPTS="-Xms128m -Xmx128m -XX:PermSize=128M -XX:MaxPermSize=128M"
# Licensed to the Apache Software Foundation (ASF) under one or more
# contributor license agreements. See the NOTICE file distributed with
# this work for additional information regarding copyright ownership.
# The ASF licenses this file to You under the Apache License, Version 2.0
# (the "License"); you may not use this file except in compliance with
# the License. You may obtain a copy of the License at

Step 5: Configuring Tomcat Manager Access.

For security reasons, no users or passwords are created for the Tomcat manager roles by default. In a production deployment, it is always best to remove the Manager application.

To set roles, user name(s) and password(s), we need to configure the tomcat-users.xml file located at $CATALINA_HOME/conf/tomcat-users.xml.

In the case of our installation, $CATALINA_HOME is located at /usr/share/apache-tomcat-6.0.32.

By default the Tomcat 6 tomcat-users.xml file will have the elements between the <tomcat-users> and </tomcat-users> tags commented-out. .

We can set the manager-gui role, for example as below:

<tomcat-users>
<role rolename="manager-gui"/>
<user username="tomcat" password="secret" roles="manager-gui"/>
</tomcat-users>

Caution should be exercised in granting multiple roles so as not to under-mind security.


Step 6 (Optional): How to Run Tomcat using Minimally Privileged (non-root) User.

In our Tomcat configuration above, we are running Tomcat as Root.

For security reasons, it is always best to run services with the only those privileges that are necessary.

There are some who make a strong case that this is not required, but it’s always best to err on the side of caution.

To run Tomcat as non-root user, we need to do the following:

1. Create the group ‘tomcat’:

[root@blanche ~]# groupadd tomcat
[root@blanche ~]# useradd -s /bin/bash -g tomcat tomcat

2. Create the user ‘tomcat’ and add this user to the tomcat group we created above.

[root@blanche ~]# groupadd tomcat
[root@blanche ~]# useradd -s /bin/bash -g tomcat tomcat

The above will create a home directory for the user tomcat in the default user home as /home/tomcat

If we want the home directory to be elsewhere, we simply specify so using the -d switch.

[root@blanche ~]# useradd -g tomcat -d /usr/share/apache-tomcat-6.0.32/tomcat tomcat

The above will create the user tomcat’s home directory as /usr/share/apache-tomcat-6.0.32/tomcat
3. Change ownership of the tomcat files to the user we created above:

[root@blanche ~]# chown -Rf tomcat.tomcat /usr/share/apache-tomcat-6.0.32/

Note: it is possible to enhance our security still further by making certain files and directory read-only. This will not be covered in this post and care should be used when setting such permissions.
4. Adjust the start/stop service script we created above. In our new script, we need to su to the user tomcat:

#!/bin/bash
# description: Tomcat Start Stop Restart
# processname: tomcat
# chkconfig: 234 20 80
JAVA_HOME=/usr/java/jdk1.6.0_34
export JAVA_HOME
PATH=$JAVA_HOME/bin:$PATH
export PATH
TOMCAT_HOME=/usr/share/apache-tomcat-6.0.35/bin

case $1 in
start)
/bin/su tomcat $TOMCAT_HOME/startup.sh
;;
stop)
/bin/su tomcat $TOMCAT_HOME/shutdown.sh
;;
restart)
/bin/su tomcat $TOMCAT_HOME/shutdown.sh
/bin/su tomcat $TOMCAT_HOME/startup.sh
;;
esac
exit 0

Step 7 (Optional): How to Run Tomcat on Port 80 as Non-Root User.

Note: the following applies when you are running Tomcat in “stand alone” mode. That is, you are running Tomcat without Apache in front of it.

To run services below port 1024 as a user other than root, you can add the following to your IP tables:

[root@blanche ~]# iptables -t nat -A PREROUTING -p tcp -m tcp --dport 80 -j REDIRECT --to-ports 8080
[root@blanche ~]# iptables -t nat -A PREROUTING -p udp -m udp --dport 80 -j REDIRECT --to-ports 8080

Learn More About Apache Tomcat