One thing that has always puzzled me about Linux Containers was why it is necessary to configure the network address in two places – the container configuration, and the operating system configuration. The short answer is that it isn't.
If you configure network addresses statically within the container configuration :-
» grep net /var/lib/lxc/mango/config # networking lxc.network.type = veth lxc.network.flags = up lxc.network.link = br0 lxc.network.ipv4 = 10.0.0.35/16 lxc.network.ipv4.gateway = 10.0.0.1 lxc.network.ipv6 = 2001:0db8:ca2c:dead:0000:0000:0000:000a/64 lxc.network.ipv6.gateway = 2001:0db8:ca2c:dead:0000:0000:0000:0001
Then the configuration within the container's operating system can simply be :-
» cat /var/lib/lxc/mango/rootfs/etc/network/interfaces auto lo iface lo inet loopback auto eth0 iface eth0 inet manual iface eth0 inet6 manual
And that works fine.