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Author: Bruce Grant, Jr. (BX)
Published: April 15, 2008
Installing Tomcat on Ubuntu 7.10
How I got my server up Part VI: a Guide for Linux Novices
This guide will walk through how to install and configure a Tomcat application server tied into Apache using mod_jk on a newly installed Ubuntu Linux Server and is meant for the complete Linux novice. The guide assumes readers have a moderate degree of experience with Tomcat, Apache and Java and application servers in general. This is the sixth installment of a series of articles explaining the technologies used to bring this web site online.
This guide explains how I installed and configured Tomcat to power this web site on an Ubuntu server. Why did I use Tomcat? My goal was to create a web site that would be really easy to maintain once I got it up. In later articles I'll explain the specific frameworks I used inside of Tomcat that made creating and maintaining this site a snap. So lets get on with it.
Java already Installed
Fedora allows multiple versions of Java to be installed simultaneously and then has a mechanism to determine which is the default. If you're following my guides then you won't hava Java installed already and won't have to worry about dealing with previously installed versions of Java. If you have Java installed pay close attention to sections I.2.D and I.2.E.

Assumptions
This guide assumes that you have a working knowledge of Java, Tomcat and web applications in general. It assumes you've already installed Apache2 (see previouse guide). It also assumes you have "sysvconfig" installed to manage services:
sudo apt-get install sysvconfig
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  1. Installing Tomcat on Ubuntu 7.10
    1. Java Fun
      The way that Ubuntu installs Java from prepared packages may be problematic for a production application server. Don't trust it.
      Each version of Java has a direct download page which you may use to download from the command line.
      1. Download Java
        1. Open the Java Download Page
        2. At the top of the page you'll find a link "Previous Snapshot Releases" click it and scroll down to the binary release you want and click it
        3. Scroll down to Linux Platform and find the Linux self-extracting JDK file
        4. Remember the URL and jump over to a terminal for your server and find a temporary directory to run this command in:
          Download JDK
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          1 2 sudo wget http://www.java.net/download/jdk6/.../jdk-6u2-bin-b02-linux-i586.bin 3
          Line 2.
          Change the URL to the one you want to download. Also note I'm using wget to download the file over HTTP, if you don't have wget you'll need to get it: sudo apt-get install wget
      2. Setting up Java
        1. Go to the directory where you downloaded the JDK
        2. Make the file executable and execute it
          1sudo chmod+x jdk-6u2-bin-b02-linux-i586.bin 2 sudo ./jdk-6u2-bin-b02-linux-i586.bin 3
          Line 2.
          After executing it you'll need to hit space bar to scroll through the license agreement and type yes at the bottom to accept it.
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        3. You now have a folder containing the JDK. Mine was named ./jdk1.6.2_02. We need to move it to its final destination in /usr/lib. I renamed the directory also so it's easier to manage.
          sudo mv ./jdk1.6.2_02 /usr/lib/Java6u2
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        4. As noted above Ubuntu wants to know about installed versions of java and manage which one is the "default" version to use. So the following will tell Ubuntu about the JDK version we just installed.
          sudo update-alternatives --install /usr/bin/java java /usr/lib/Java6u2/bin/java 300
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        5. If you have other versions of Java installed you'll want to also set the new JDK as the default. After running the command below simply select the number of the just installed JDK.
          sudo update-alternatives --config java
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      3. Set Java Paths
        We need to specify the JAVA_HOME and CLASSPATH environment variables both globally and in your local user settings, just to be safe.
        1. Set Global Paths
          Modify File: sudo nano /etc/environment
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          1 CLASSPATH=.:/usr/lib/Java6u2/bin 2 JAVA_HOME=/usr/lib/Java6u2 3
          Line 1.
          Add these lines to the bottom of the file and change the path to reflect where you put the JDK.

          Modify File: sudo nano /etc/rc.local
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          export JAVA_HOME=/usr/lib/Java6u2
        2. Set User Paths
          Modify Files
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          1 sudo nano /home/myusername/.bashrc 2 sudo nano /root/.bashrc 3 4 CLASSPATH=.:/usr/lib/Java6u2/bin 5 export JAVA_HOME=/usr/lib/Java6u4 6 export PATH=$PATH:$JAVA_HOME/bin
          Line 1.
          Add lines 4 - 6 to the bottom of this file (note change myusername to the username you usually log in with)
          Line 2.
          Add lines 4 - 6 to the bottom of this file
    2. Tomcat
      Again I recommend you download Tomcat and install it manually instead of relying on a package.
      1. Download Tomcat
        1. Jump to the Tomcat download page
        2. Pick the version you want and remember the URL of tar.gz version
        3. Jump over to a terminal for your server, find a temporary directory to run this command in:
          Download Tomcat
          Copy
          1 2 sudo wget http://mirrors.enquira.com/apache/tomcat/tomcat-6/v6.0.14/bin/apache-tomcat-6.0.14.tar.gz 3
          Line 2.
          Change the URL to the one you want to download. Also note I'm using wget to download the file over HTTP, if you don't have wget you'll need to get it: sudo apt-get install wget
        4. Unpack tomcat and copy it to its final home
          Unpack Tomcat
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          1 sudo tar zxvf /temp/apache-tomcat-6.0.14.tar.gz 2 sudo cp -R /temp/apache-tomcat-6.0.14 /usr/share/tomcat6 3
          Line 1.
          Change path to tomcat for what you downloaded.
          Line 2.
          Change path to tomcat directory unpacked.
      2. Set Tomcat Paths
        We need to specify the CATALINA_HOME environment variable both globally and in your local user settings, just to be safe.
        1. Set Global Paths
          Modify File: sudo nano /etc/environment
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          1 2 CATALINA_HOME=/usr/share/tomcat6 3
          Line 1.
          Add this line to the bottom of the file and change the path to reflect where you put tomcat.
        2. Set User Paths
          Modify Files
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          1 sudo nano /home/myusername/.bashrc 2 sudo nano /root/.bashrc 3 4 export CATALINA_HOME=/usr/share/tomcat6
          Line 1.
          Add line 4 to the bottom of this file (note change myusername to the username you usually log in with)
          Line 2.
          Add line 4 to the bottom of this file
      3. Tomcat in Headless Mode
        I run my server without a windowing environment (gnome, kde, etc.) since I don't need one and it sucks resources from my server. However, I do have Java code that needs a display device context in order to do image manipulation (Canvas, Panel and others also require it). If you're in the same boat this section is for you, otherwise push on to the next.
        1. Modify Tomcat Startup Script
          We have to change the Tomcat startup script to start the Java VM with an additional command-line argument so it will run in headless mode (no graphics context) and fool classes like Canvas and Panel by giving them a mock device context.
          Modify File: sudo cp /usr/share/tomcat6/bin/catalina.sh
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           1 exec "$_RUNJDB" $JAVA_OPTS $CATALINA_OPTS \  2 -Djava.endorsed.dirs="$JAVA_ENDORSED_DIRS" -classpath "$CLASSPATH" \  3 -sourcepath "$CATALINA_HOME"/../../java \  4 -Djava.security.manager \  5 -Djava.security.policy=="$CATALINA_BASE"/conf/catalina.policy \  6 -Dcatalina.base="$CATALINA_BASE" \  7 -Dcatalina.home="$CATALINA_HOME" \  8 -Djava.io.tmpdir="$CATALINA_TMPDIR" \  9 -Djava.awt.headless=true \ 10 org.apache.catalina.startup.Bootstrap "$@" start
          Line 1.
          Look everywhere in the file where you see exec $_RUNJDB or exec $_RUNJAVA and add -Djava.awt.headless=true
          Line 9.
          Here's where I added it in this example
        2. X-Windows Virtual Frame buffer (XVbf)
          XVbf is a lightweight but fast virtual framebuffer X11 server enabling all the graphical capabilities Java might require but without requiring a full x-windows installation.
          sudo apt-get install xvfb
      4. Install Tomcat as Service
        1. Copy the tomcat startup script to the system 5 init daemon so it will startup automatically on reboot
          sudo cp /usr/share/tomcat6/bin/catalina.sh /etc/init.d/tomcat
        2. Run sysvconfig
          sudo sysvconfig
        3. You'll now see a menu. Scroll to Enable/Disable and hit return
        4. Scroll down until you see tomcat and hit space bar (it will now startup on reboot)
        5. Exit this screen and then scroll to finished and hit return
        6. Then scroll down to quit and hit return
      5. Controlling Tomcat
        Controlling Tomcat
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        sudo service tomcat stop sudo service tomcat start sudo service tomcat restart
    3. Tieing Tomcat to Apache - mod_jk
      Tomcat's web serving abilities have come a long way but I still prefer to put Apache in front of Tomcat to benefit from Apache's many extensions: mod-redirect, mod-ssl, mod-gzip, etc.
      1. Install mod_jk Apache Apache Module
        sudo apt-get install libapache2-mod-jk
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      2. Configure mod_jk
        Modify File: sudo nano /etc/apache2/apache2.conf
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         1 # The location where mod_jk will find the workers definitions  2 JkWorkersFile /etc/libapache2-mod-jk/workers.properties  3  4 # The location where mod_jk is going to place its log file  5 JkLogFile /var/log/apache2/mod_jk.log  6  7 # Set the jk log level [debug/error/info]  8 JkLogLevel info  9 10 # Select the log format 11 JkLogStampFormat "[%a %b %d %H:%M:%S %Y] " 12 13 # JkOptions indicate to send SSL KEY SIZE, 14 JkOptions +ForwardKeySize +ForwardURICompat -ForwardDirectories
        Line 1.
        Add all of this to the bottom of the file. I didn't put this into a separate /etc/apache2/sites-available site file because I want it available to all sites.
        Line 2.
        Note this is the location of the workers file we'll modify in a minute.
        Line 5.
        Change this if you don't like the path I used for the mod_jk log file.
        Line 8.
        Change this if you need to debug.

        Modify File: sudo nano /etc/libapache2-mod-jk/workers.properties
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         1 worker.ajp13_worker.port=8009  2 worker.ajp13_worker.host=localhost  3 worker.ajp13_worker.type=ajp13  4 worker.ajp13_worker.connection_pool_size=250  5 worker.ajp13_worker.connection_pool_minsize=100  6 worker.ajp13_worker.connection_pool_timeout=600  7 worker.ajp13_worker.socket_timeout=60  8 worker.ajp13_worker.socket_keepalive=1  9 worker.ajp13_worker.connect_timeout=15000 10 worker.ajp13_worker.prepost_timeout=10000
        Line 1.
        It's beyond the scope of this guide to explain mod_jk or what this file is. Look it up in google and you'll find all you need to know. These are my settings arrived at after some hard lessons. They're dialed into a high-perforance web site. I had problems with mod_jk dieing when my server was under load. These settings fixed it.
      3. Apache to Tomcat via mod_jk
        Lastly you need to modify your virtual hosts to specify which URL patterns to forward requests on to Tomcat via mod_jk.
        Directory Mounted to Tomcat
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        1 <Location "/webapp_name/*"> 2 ExpiresDefault "now" 3 JkMount ajp13_worker 4 </Location>
        Line 1.
        This appears in my /etc/apache2/sites-available/default virtual host. I have a webapp in tomcat named webapp_name. Any url with /webapp_name will be forwarded to tomcat from apache.
        Line 2.
        I don't want any content cached by browsers since all content from here is dynamic (uses mod_expires).
        Line 3.
        Mounts this URL path to Tomcat using the ajp13_worker specified in my workers.properties file (see above).
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