Setup :
With terraform, I created vms in Azure. Them, I ssh into one of them and bootstrap a manual cloud.
The problem is that juju wipes the dns configuration in systemd-resolve. Before the bootstrap action, my systemd-resolve status shows a list of 4 dns servers, as well as a DNS domain. After launching the bootstrap, that information is removed from systemd-resolve and the bootstrap hangs at "Running machine configuration script...".
While it was hanging there, I confirmed in another terminal that the dns info was gone and that my vm was not able to resolve anythin anymore. A simple sudo apt update returns resolution errors.
To work around this, while the bootstrap was hanging, I set the dns back to its original value with systemd-resolve --set-dns="xx.xx.xx.x" --set-domain="my.domain.com" --interface="eth0" . This allowed the bootstrap to
continue normally.
I can confirm that this happens with juju 2.8.6/stable and 2.8.5 on bionic vms (ubuntu-18.04.5-latest in azure)
juju doesn't directly change the systemd-resolve configuration as far as I am aware.
It does use an upstream library github.
More investigation needed to understand what is messing with the systemd resolve config.