First create a bridge as per instructions here https://wiki.debian.org/LXC/SimpleBridge
My interface was showing em1 instead of eth0 so be sure to replace eth0 with whatever you got.
# Comment out the following:
# The primary network interface
#allow-hotplug eth0
#iface eth0 inet dhcp
auto br0
iface br0 inet dhcp
bridge_ports eth0
bridge_fd 0
bridge_maxwait 0
Then create your container with a profile:
lxc profile create bridged
lxc profile device add bridged eth0 nic nictype=bridged parent=br0
lxc launch ubuntu/vivid test --profile=bridged
again replace eth0 with whatever you got, I think this is redundant given we already has a bridge called br0, in fact I did this in reverse order. Created the profile and the container but I got the following error:
Error calling 'lxd forkstart db01 /var/lib/lxd/containers /var/log/lxd/db01/lxc.conf': err='exit status 1'
Fixed this by creating the bridge as described above.