Since a couple of days, newly launched xenial, bionic, focal, jammy containers have no IPv4 connectivity.
$ lxc launch images:ubuntu/bionic/amd64 bionic-test
Creating bionic-test
Starting bionic-test
$ lxc launch images:ubuntu/focal/amd64 focal-test
Creating focal-test
Starting focal-test
$ lxc launch images:ubuntu/jammy/amd64 jammy-test
Creating jammy-test
Starting jammy-test
As you can see, they only get IPv6 address assigned, but no IPv4:
$ lxc list|grep test
| bionic-test | RUNNING | | fd42:b5d:f6dd:6b21:216:3eff:fee1:5503 (eth0) | CONTAINER | 0 |
| focal-test | RUNNING | | fd42:b5d:f6dd:6b21:216:3eff:fe0d:e1f6 (eth0) | CONTAINER | 0 |
| jammy-test | RUNNING | | fd42:b5d:f6dd:6b21:216:3eff:fe44:d6ee (eth0) | CONTAINER | 0 |
This is probably because of:
root@bionic-test:~# cat /etc/network/interfaces
# ifupdown has been replaced by netplan(5) on this system. See
# /etc/netplan for current configuration.
# To re-enable ifupdown on this system, you can run:
# sudo apt install ifupdown
root@bionic-test:~# ls /etc/netplan/
root@bionic-test:~#
root@focal-test:~# ls /etc/netplan/
root@focal-test:~#
I was able to reproduce it on several hosts.