I don't think we can use the request headers. If we're behind a proxy like Apache or lighttpd (which is probably how most people run roundup) the request headers are irrelevant. Your config.TRACKER_NAME will be something like "http://mainserver/bugs" and the request headers will look like:

HTTP_HOST = localhost:54321
SERVER_NAME = localhost
SERVER_PORT = 54321

We'd have to have access to the http configuration to truly validate config.TRACKER_NAME against the request headers.

I have, however, tried to clarify the roundup-server man page slightly and added an EXAMPLE section that will hopefully make it more obvious how the name=tracker_instance stuff is used.

I've checked that change into CVS. If you have suggestions about how to improve it further, please let me know.