We distribute /usr/share/nova/interfaces.template that looks like this:

DEVICE="{{ name }}"
NM_CONTROLLED="no"
ONBOOT=yes
TYPE=Ethernet
BOOTPROTO=static
IPADDR={{ address }}
NETMASK={{ netmask }}
BROADCAST={{ broadcast }}
GATEWAY={{ gateway }}
DNS1={{ dns }}

#if $use_ipv6
IPV6INIT=yes
IPV6ADDR={{ address_v6 }}
#end if

There are two problems here:

1. The get_injected_network_template function (in nova.virt.netutils) does not call this with top-level keys matching the ones used in the template, so all the references there (e.g., {{ name }}) expand to the empty string.  The template actually receives a top-level 'interfaces' key with a list of network interfaces to inject.  We could fix this template, but...


2. cloud-init expects a debian-ish "/etc/network/interfaces" format (see, e.g., cloudinit/distros/rhel.py).  So in fact we need a template that looks like this:

{% for interface in interfaces %}
auto {{ interface.name }}
iface {{ interface.name }} inet static
  address {{ interface.address }}
  netmask {{ interface.netmask }}
  broadcast {{ interface.broadcast }}
  gateway {{ interface.gateway }}
  dns-nameservers {{ interface.dns }}
{% endfor %}