[Nix-dev] network interface naming

[Mathijs Kwik]

Hi all,

Some time ago, udev changed to stable interface names for networking.
So instead of eth0 and eth1 you would get enp0s3 (wired) and wlp1s5
(wireless) for example. And I think there existed a (nixos?) option to
stick to the previous behaviour for some time.

I recently upgraded an older system to our new 14.04 release and noticed
it now uses the new naming scheme, while it previously still used the
old scheme. I could not find the use-old-scheme option, nor did I enable
such a thing in the past.

I do not mind the new names (actually, I prefer them), so I changed all
references to the new names (firewall rules, custom networking setup,
vpn tweaking). This works fine on the real system, but I run into issues
when running such configuations in a vm. It seems qemu/kvm still has the
guest create eth0. 

Now, I can of course parameterise the entire config by an interface name
to easily modify the configuration for a vm build. But this is somewhat
ugly, especially because of the networking.interfaces.<name>. attrset.

But I'm hoping there's a better/nicer way to either force some interface
name to vms, or have the real system stick to the old naming scheme.

Any pointers?
Thanks,
Mathijs