Comment 4 for bug 1640556

Verified.

cat > update <<"EOF"
#!/bin/sh
set -e
m=http://archive.ubuntu.com/ubuntu
rel=$(lsb_release -sc)
echo "deb $m $rel-proposed main" > /etc/apt/sources.list.d/proposed.list
grep -q "backports" /etc/apt/sources.list ||
   echo "deb $m $rel-backports main universe" > /etc/apt/sources.list.d/backports.list
apt-get update -q
apt-get install -qy cloud-init
if [ "$1" = "backports" ]; then
   apt-get install -qy -t $rel-backports lxd
fi
EOF

$ cat > user-data <<EOF
#cloud-config
lxd:
  bridge:
    mode: new
    name: lxdbr1
    ipv4_address: 10.5.0.1
    ipv4_netmask: 24
    ipv4_nat: true
  init:
    storage_backend: dir
EOF

$ lxc init ubuntu-daily:xenial x1 "--config=user.user-data=$(cat user-data)"
$ sudo mount-image-callback --system-resolvconf lxd:x1 -- chroot _MOUNTPOINT_ /bin/sh -s backports <update
$ lxc start x1
$ sleep 10

$ lxc exec x1 ip addr show dev lxdbr1
2: lxdbr1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN group default qlen 1000
    link/ether ee:0b:ab:b3:4e:9a brd ff:ff:ff:ff:ff:ff
    inet 10.5.0.1/24 scope global lxdbr1
       valid_lft forever preferred_lft forever
    inet6 fe80::ec0b:abff:feb3:4e9a/64 scope link
       valid_lft forever preferred_lft forever