I need to nuke my existing system and reinstall everything clean. However, in the process of doing this, I need to have Virtualmin running on both the old site and the new site so I can restore the virtual hosts on the new site before taking down the old site.
Is there some graceful way of doing this with a single license or do I have to purchase 2 licenses even though only one is going to be used except for a week or two during the transition?
Also, is Debian 9 supported in the new Virtualmin installer? If not when will it be supported, or, failing that, the equivalent Ubuntu?
You don’t need another license, and you don’t need to do anything special; just install the license on the new machine. It might complain about multiple servers running on the license, but it won’t stop it from working (and we don’t even get a notification about it until it’s been running on multiple servers for a while). You can just turn off your old server when you’re finished with your migration, and any warnings will clear on their own in a couple days.
Debian 9 is supported in the new installer and is the version of Debian we recommend for new installations.