Comment 1 for bug 1874337

I have prepared xenial containers (last ones that used ifupdown / resolvconf by default) and configured it with:
- default resolvconf & dhcp acquired dns
- above, but with an extra dns nameserver specified in eni
- with resolvconf removed and static resolv.conf configuration
- with dhclient removed and static ip configuration

I've staged above updates in a bileto PPA and will execute upgrade to bionic, then upgrade to focal + bileto PPA.

The expectation is for every configuration above, that the configuration survives the upgrade, and dns configurations still work.