Network unreachable after adding new bridged interface

LXD
10

I’ve tried this on a fresh 18.04 VM and it works:

sudo apt install ifupdown bridge-utils

/etc/network/interfaces

auto lo
iface lo inet loopback

iface enp0s3 inet manual

# Bridge setup
auto br0
iface br0 inet dhcp
        bridge_ports enp0s3

Reboot and I see:

ip a

2: enp0s3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel master br0 state UP group default qlen 1000
    link/ether 08:00:27:76:da:6e brd ff:ff:ff:ff:ff:ff
    inet6 fe80::a00:27ff:fe76:da6e/64 scope link 
       valid_lft forever preferred_lft forever
3: br0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
    link/ether 08:00:27:76:da:6e brd ff:ff:ff:ff:ff:ff
    inet 192.168.1.129/24 brd 192.168.1.255 scope global br0
       valid_lft forever preferred_lft forever
    inet6 fe80::a00:27ff:fe76:da6e/64 scope link 
       valid_lft forever preferred_lft forever

I wouldn’t suggest mixing netplan and interfaces files though, stick with one or the other.