For more about this, see:
http://httpd.apache.org/docs/2.2/mod/mod_proxy.html
https://confluence.atlassian.com/display/DOC/Using+Apache+with+virtual+hosts+and+mod_proxy
Here my config to pass to my Atlassian JIRA (Confluence is same, same), that runs on the server, port 8080.
The "Deny from 80 10.40.62.77" is actually to stop a spammer identified from that IP Address
<VirtualHost *:80>
ServerAdmin bnp@mos-eisley.dk
ServerName jira.mos-eisley.dk
ServerAlias jira
ProxyPass / http://jira.mos-eisley.dk:8080/
ProxyPassReverse / http://jira.mos-eisley.dk:8080/
<Proxy *>
Order Allow,Deny
Allow from all
Deny from 80 10.40.62.77
Deny from none
</Proxy>
</VirtualHost>
This also requires 3 extra parameters (scheme,proxyName,proxyPort) to the Tomcat's server.xml; otherwise JIRA complains
<Connector port="8080" maxThreads="150" minSpareThreads="25" maxSpareThreads="75" connectionTimeout="20000" enableLookups="false" maxHttpHeaderSize="8192" protocol="HTTP/1.1" useBodyEncodingForURI="true" redirectPort="8443" acceptCount="100" disableUploadTimeout="true" scheme="http" proxyName="jira.mos-eisley.dk" proxyPort="80"/>