We have a Citrix XenServer setup, and while I personally lean more towards Dev than Ops, I've got an issue that's been bugging me.

When you provision a new (Linux/Ubuntu) guest, how do you get it to have the correct IP-address? I'd want my application servers to exist in the range of 10.20.0.0/24, preferably being .1, .2, etc, so I can keep my sanity.

I guess that the actual IP-address is something set in Linux itself, and Xen can't touch that, but then what's the best practice for getting it done? If you set up DHCP, don't you just move the problem to getting the adapters the "correct" MAC-addresses? Do you just have to hardcode a large table of MAC-addresses to IP-addresses, and then provision new guests always with the correct MAC-address on the virtual ethernet adapter?

What we currently do is have an image of a "app server" that we boot up a new instance of, and then finalize it (with a script) that (among other things) modifies the /etc/networking/interface file to give it the correct IP. But that feels dirty to me, and I feel like surely there must a better way. Please enlighten me?