Is it possible to move an IPv4 address from a droplet that should not be publicly accessible to one that should have multiple public IPv4 addresses?
I am contemplating a multi-tier architecture that calls for several application and database droplets which should not be publicly accessible - . These droplets should only be accessible indirectly through a reverse proxy/load balancer (which would also act as a bastion to forward ssh, software updates, etc.), so the public network interface would be disabled for security. Thus, those IPv4 addresses will be going to waste. The load balancer/bastion should be the only droplet publicly accessible.
However, I would very much like to be able to serve multiple IPv4 addresses from that one reverse proxy/load balancer droplet. I understand that you are trying to conserve precious public IPv4 addresses, but I would have several unused, inaccessable public IPv4 addresses just going to waste on the application and database droplets. Is there any way to move these unused addresses to be secondary addresses on my one publicly addressable droplet? Rather than just wasting them? (If not, is there some efficient, secure workaround other than just buying extra droplets that I don't really need, just solely to get the public IPv4's that go with them?)
Also, I understand that this is a pretty common architecture design, limiting public access to just one or a handful of special servers, so despite your stated goal of conserving public IPv4 addresses, you probably have a great many of them going to waste right now, stranded on droplets which have their public access deliberately unused, inaccessible or disabled. It seems to me that if your goal is truly to conserve public IPv4 addresses, it would seem the best way to make efficient use of them would be for you to not automatically issue a public IPv4 with every droplet, but rather rent droplets and public IPv4's separately as ala carte services (adjusting the droplet price accordingly), and allow customers to flexibly assign any number of public IPv4's to any droplet that needs them. This would much more efficiently allocate limited public IPv4's where they are truly needed, while also allowing your customers the flexibility to choose any architecture that suits them.