My specific context is NeCTAR, but I'm asking here more generally about the capabilities of OpenStack.

I'm dealing with a situation where I have to request a license key for a 3rd party product to run on NeCTAR / OpenStack. The license key is tied to the MAC address of the "machine" it runs on.

Unfortunately, it appears that OpenStack does not provide a simple way to assign a specific MAC address to a virtual instance as you are configuring / instantiating it. (Certainly, it is not possible via the Grizzly Dashboard ... though perhaps there is another way.) And if I terminate the existing and create a new instance, the new one will have a different MAC address and IP address ... and I'll need to ask for a new license key.

I have been told of a partial workaround that involves "rebuilding" an instance from a fresh image. When you do this, the MAC address and IP address for the instance remain the same. Unfortunately, so does the "flavour"; e.g. the #vCPUs and the memory size ... apparently.

What I'm asking is whether there is a way to change an instance's memory size and # vCPUs that doesn't also entail changing the instance's MAC or IP addresses. (Changing the MAC address has the problem of license key. Changing the IP address has other problems.)