I like to have the Tomcat manager webapp installed on each instance, so I can play with the webapps, and see how many active sessions there are. To do this, make a file called manager.xml file in the webapps directory of your Tomcat instance. One I like to use is this:

    <Context path="/manager"
        docBase="/usr/local/tomcat/server/webapps/manager"
        debug="0"
        privileged="true">

    <ResourceLink name="users"
            global="UserDatabase"
            type="org.apache.catalina.UserDatabase"/>

    <Valve className="org.apache.catalina.valves.RemoteAddrValve"

Here's a brief step by step guide to running more than one instance of Tomcat on a single machine.

Step 1: Install the Tomcat files

Download Tomcat 4.1 or 5.5, and unzip it into an appropriate directory. I usually put it in /usr/local, so it ends up in a directory called /usr/local/apache-tomcat-5.5.17 (5.5.17 being the current version as of this writing), and make a symlink named /usr/local/tomcat to that directory. When later versions come out, I can unzip them and relink, leaving the older version in case things don't work out (which rarely if ever happens, but I'm paranoid).

The most basic setup of Tomcat involves unzipping the distribution files somewhere on your system, dropping your application into the webapps directory, and firing the server up. This is a fine quick start to run a single app on your own machine, but Tomcat offers a much more powerful way to organize production servers and complex developer setups.

If you read down a ways in the RUNNING.txt file in the tomcat installation bundle, you’ll find a section called “Advanced Configuration - Multiple Tomcat Instances”. This describes how to split your Tomcat installation into two directories, the $CATALINA_HOME directory for the Tomcat installation files, and the $CATALINA_BASE directory with the runtime files. Setting these two environment variables when you start up Tomcat controls where the server will look for its files.

It's easy to just unzip the Tomcat installation files, drop your webapp into place, and start up the server. But although that works fine for a quick start, once you get into production use, or more complex development scenarios, there are some basic things you can do to make your life easier.

Installing and configuring Tomcat is fairly straightforward if you follow the documentation that comes with it. But putting it into production requires more thought if you want to make sure you have restful nights and more productive days.

This guide is intended to help systems administrators and Java developers who are responsible for applications running on Tomcat in production to make sure their serves are stable, fast, and easy to manage.