I have a bridge br0 which is being used as docker's bridge interface and bridges to our vpn with an ipv6 interface. When I set up this bridge manually, everything works fine and I can connect to the vpn (from my laptop) and ping bbbb::2000 as well as all the docker containers (e.g. bbbb::242:ac11:4) just fine.
Leaving it as a config file, however, causes the boot process to take several minutes with the message cloud-init-nonet waiting [10|60|120]s for network device coming up all the time, followed (eventually) by Waiting up to [60|120] more seconds for network configuration.... Once it finally boots, the bridge does work but the long restart cycle concerns me.
So my question (amongst other things) is: what is wrong with my configuration file such that boot takes such a long time?
My initial thought was that perhaps having bridge_ports tap0 in there is causing it to fail to boot until tap0 is up, but removing bridge_ports prevents the bridge interface from working at all (and keeps the long boot time) so it must be something else.
/etc/network/interfaces.d/br0.cfg
# docker bridge network
auto br0
iface br0 inet6 static
bridge_ports tap0
bridge_stp off
up echo 0 > /sys/devices/virtual/net/br0/bridge/multicast_snooping
post-up ip addr flush tap0
address bbbb::2000
netmask 64
creating the bridge manually
brctl addbr br0
brctl addif br0 tap0
ip addr flush tap0
service docker restart
