Add support to DataSourceOVF for configuring network interfaces

[Dave Johnston]

Some of the datasources such as NoCloud offer the ability to configure network interfaces via meta-data.
It would be useful if the OVFDataSource could provide a similar feature, using OVF properties.

The OVF environment doesn't lend itself to writing a multi-line document i.e

network-interfaces: |
  iface eth0 inet static
  address 192.168.1.10
  network 192.168.1.0
  netmask 255.255.255.0
  broadcast 192.168.1.255
  gateway 192.168.1.254
  dns-nameservers 10.20.10.110 10.20.10.113
  dns-search myopwvbfs.com

Instead, indvidual properties should be used to make up the network settings, which could then be translated to the multi-line format internally.

[Dave Johnston (dave-johnston)]

I've created a potential fix for this currently on github.
https://github.com/davejohnston/cloud-init/commit/4452554ce7a86243a43a6614cf3fa7fac081ff2c

[Scott Moser (smoser)]

I haven't looked at your branch.
I'm not opposed to this, but wonder why/where you're using the ovf datasource?

Also, we could also use/re-use by just passing in a /etc/network/interfaces information as openstack config-drive does.

[James Falcon (falcojr)]

Tracked in Github Issues as https://github.com/canonical/cloud-init/issues/2408