Suppose you have your web app hosted by Tomcat at http://localhost:8080/myapp. That’s an ugly address for end users, so you want it to be accessible as http://somesystem.example.com. Here’s how you can do it with a little help from Apache via mod_proxy and mod_rewrite.

1. Install Apache:

apt-get install apache2

2. Enable optional modules:

a2enmod proxy
a2enmod proxy_http
a2enmod rewrite

3. Configure proxy (/etc/apache2/httpd.conf):

ProxyRequests Off

<Proxy *>
  Order deny,allow
  Allow from all
</Proxy>

4. Configure virtual host (/etc/apache2/sites-available/somesystem):

<VirtualHost *>
        ServerName somesystem.example.com
        RewriteEngine On
        ProxyPass / http://localhost:8080/myapp
        ProxyPassReverse / http://localhost:8080/myapp
</VirtualHost>

5. Enable virtual host:

a2ensite somesystem

6. Restart Apache:

/etc/init.d/apache2 restart

7. Enable proxy support in Tomcat (conf/server.xml):

<Connector port="8080" protocol="HTTP/1.1"
               connectionTimeout="20000"
               redirectPort="8443" proxyPort="80" />

8. Restart Tomcat

Note: It’s written for Ubuntu, but can be easily converted to other systems.