If I have many domains (potentially many thousands) doing something simple (eg a redirect), is it better to have:
a) 1 server with 1 route per domain (so many routes, each with a host matcher)
or
b) Many servers with a single route each
It looks like the HTTPS config is at server level, so would that mean a single server with many different domains might have problems with issuing SSL certificates?
Only one server may bind to a particular port at a time (unless you use separate network interfaces for each) so you would be using one server with many routes anyway.
The map handler can be used to efficiently match hostnames to classify them in whatever ways. The host matcher is also optimized if given more than 100 domains to use a binary search.