I am having a hard time getting the supposedly randomly generated passwd for the amd64 qcow2 image here:
https://cloud-images.ubuntu.com/releases/16.04/release/
I found the (perhaps outdated?) instructions here:
https://help.ubuntu.com/community/UEC/Images
Things seem to have changed, and I don't see the line in the console output, and ctrl-alt-3 for serial console doesn't work for me (i entered via virsh console vm_name).