If mac address is configured use that for interface creation

Allows setting custom mac addresses for newly created virtual interfaces.

Author: goetzk

README.md

@@ -81,6 +81,7 @@ Role Variables
         - `network`: Name of the network to which an interface should be
           attached. Must be specified if and only if the interface `type` is
           `network`.
+        - `mac`: "Hardware" address of the virtual instance, if absent one is created
         - `source`: A dict defining the host interface to which this
           VM interface should be attached. Must be specified if and only if the
           interface `type` is `direct`. Includes the following attributes:

templates/vm.xml.j2

@@ -47,6 +47,9 @@
     <interface type='network'>
       <source network='{{ interface.network }}'/>
 {% endif %}
+      {% if interface.mac %}
+      <mac address='{{ interface.mac }}'/>
+      {% endif %}
       {# if the network configuration is invalid this can still appear in the xml #}
       {# (say you enter 'bond' instead of 'bridge in your variables) #}
       <model type='virtio'/>