How did you configure the basic auth? If you are using <Directory> Directives, try changing to <Location> instead. (as the proxied requests don't actually touch an Apache directory..
Edit:
I assume you have: LoadModule proxy_ajp_module modules/mod_proxy_ajp.so
For the benefit of others, I'll answer my own question. Actually, Tomcat (since version 6) provides a quite easy solution for adding URI prefixes to webapps, by prefixing the webapp folder or WAR file name with that prefix (or those prefixes), separated by a hash. So, e.g.:
${catalina.base}/webapps/apps#my_app
${catalina.base}/webapps/apps#my_app2.war
...would make both accessible via http://localhost:8082/apps/my_app/ and http://localhost:8080/apps/my_app2/, respectively, without any further configuration in ${catalina.base}/conf/server.xml.
It is explained somewhat cryptically in the Tomcat Context Container reference, but see this kind message on the Tomcat-users mailing list helped me a lot.
Unfortunately, there's a catch: apparently, Cocoon (up to 2.1.11, haven't tested with 2.2 apps) chokes on webapps whose paths contain a hash (see https://issues.apache.org/jira/browse/COCOON-2270).
Yet, there is a workaround for those Cocoon-based webapps, as shown in following configuration steps:
- move the folder or WAR file containing the webapp outside of the host's appBase path, e.g.: F:\cocoonApps\my_CocoonApp
add a file ${catalina.base}\conf\Catalina[host name][prefix]#[app name].xml, e.g.: ${catalina.base}\conf\Catalina\localhost\apps#my_CocoonApp.xml, with following content:
<Context docBase="F:/cocoonApps/my_CocoonApp"/>
Using this workaround, even Cocoon webapps are happy when accessed at e.g. http://localhost:8082/apps/my_CocoonApp/. This could allow for quite flexible managment overhead of Tomcat webapps:
- non-Cocoon-based webapps: just add them in the Host's appBase, prefixing the name of the folder or WAR file with the desired prefix(es), separated with a hash (#). Adding new non-Cocoon webapps requires no further steps than storing them with the desired URI prefix.
- Cocoon-based webapps: store them outside of the Host's appBase, with just the unprefixed webapp name. Additionally, add a context file for each Cocoon-based webapp, specifying the of the webapp as explained above. This additional step then is only needed for Cocoon-based webapps.
With the Apache proxy settings explained in my original question, this makes it possible to flexibly add Tomcat apps and have them reverse proxied behind Apache using the /apps/ URI prefix.
Best Answer
For Windows you can use: http://code.google.com/p/ospy/. In Linux you have strace.