Comment 1 for bug 2039555

This isn't something that the charm controls. From "https://docs.openstack.org/nova/latest/admin/configuring-migrations.html":

Enable password-less SSH so that root on one compute host can log on to any other compute host without providing a password. The libvirtd daemon, which runs as root, uses the SSH protocol to copy the instance to the destination and can’t know the passwords of all compute hosts.

e.g. it's to do with libvirtd and nova. Setting the charm bug to invalid.