I need a rewrite rule like this :

regex[pattern='/'] -> redirect['/homepage.html']

But RFC-2616 says that the "Location" header should be an absolute URL.
So I need a way to convert "/homepage.html" to an absolute URL.

One way to do this is :

redirect['%{SCHEME}://%{i,Host}/homepage.html']

but it will not work for HTTP 1.0 requests (without a host header).

A better way would be to use HttpServerExchange.getHostAndPort(), maybe through a new ExchangeAttribute type. For example :

redirect['%{SCHEME}://%{HOST_AND_PORT}/homepage.html']