I think this method might break if/when there are multiple containers, multiple interfaces for one container, multiple docker daemons, or another bridge devices in use for other purposes (i.e. qemu-kvm / libvirt) or multiple docker daemons running.  I see too that pinning a ``veth*`` device to a specific container is not obvious.  I played around trying to solve this but couldn't figure it out (presumably this is what your RFE is about).

For now, since it's probably reasonable (for testing purposes) to expect no other containers will be starting/stopping except those by a test.  My suggestion here is:

1)  Grab the proper bridge device for the test container by ID/name ``docker inspect --format='{{.NetworkSettings.Bridge}}'  <container>``.
2)  Then pass the bridge name to this method (e.g. ``brctl show docker0``) and just return a ``set()`` of all the ``veth*`` names.
3)  Capture the ``set()`` of interface names before/after starting the test container
4) The started container's net device name(s) are the resulting ``set()`` from ``after - before`` https://docs.python.org/release/2.6.8/library/stdtypes.html#set.difference.