Tomcat: The Definitive Guide, 2nd Edition

Relocating the Web Applications Directory

Depending on how you install and use Tomcat, you may not want to store your web application's files in the Tomcat distribution's directory tree. For example, if you plan to upgrade your installation of Tomcat periodically, you probably shouldn't modify Tomcat's files—for instance, CATALINA_HOME/conf/server.xml, which you will likely need or want to modify in order to configure Tomcat for your site^[8]—because when you install a newer version of Tomcat's files into the Tomcat installation directory tree, you may overwrite the server.xml and any other configuration files that you modified for your site. This is the case whether you use an operating-system-specific package of Tomcat (an RPM package, etc.) or an operating-system-neutral archive of Tomcat (.zip or .tar.gz). Upgrading the Tomcat package means that the native package manager may replace your configuration files with stock versions from any new version of the same package that you upgrade to. Usually, package managers save the file they're replacing if it is a known configuration file, but even then it's a pain to know what you need to do to get your site back in running order. Regardless of how you installed Tomcat, though, it may be a good idea to keep your web site's files cleanly separate from the Tomcat distribution files.

Another scenario in which you may not want to store your web application files in the Tomcat distribution's directory tree is if you install one copy of the ...