I have recently been forced to change the IP address on my server multiple times due to network reconfigurations by my provider. Virtualmin has an option to "Change IP Addresses", but it is somewhat limited, since it will only allow a single IP address to be active at a given time.
When changing IP addresses, it is best to maintain uptime by having a "grace period" where both the old IP and the new IP address are active on the system. This allows time for DNS propagation delays and for users to refresh their browsers. It is very easy to do with a virtual interface.
There are also similar cases where a system may have multiple NICs, each with their own IP address for redundancy.
In the Webmin Apache module, under Networking and Addresses, there is an option to "Include all addresses", which inserts "*:80" into httpd.conf. However, in the Virtualmin Module Config, a single IP address must be selected, which is determined automatically by default from the primary interface.
Would it be possible to enhance Virtualmin by allowing for multiple (or ALL - "*") interfaces to be designated as VirtualHost directives in Apache?