Fixed DHCP addresses in libvirt

The libvirt DHCP service can deal out fixed IP addresses.  Yes, you could simply configure the guest OS with a static IP, but that's beside the point.  A DHCP service should be able to handle fixed addresses and, earlier in the game, I didn't think libvirt was capable of it.  But it is!

Just add a host element to the default network XML file using virsh net-edit default.

<network>
  <name>default</name>
  <uuid>5c0448c7-4240-4325-9a80-eb9f575c962e</uuid>
  <forward mode='nat'/>
  <bridge name='virbr0' stp='on' delay='0' />
  <mac address='52:54:00:BE:58:83'/>
  <ip address='192.168.122.1' netmask='255.255.255.0'>
    <dhcp>
      <range start='192.168.122.128' end='192.168.122.254' />
      <host mac='52:54:00:c9:06:c5' name='router122' ip='192.168.122.200' />
    </dhcp>
  </ip>
</network>

Of course, this same principle applies to other virtual networks.  The reason I doubted it at first is that virt-manager 0.9.5 doesn't expose this level of customization in its GUI.

Everything you need to know about network configuration can be found at libvirt networking.