Logs on the controller all appear to be empty.
juju@controller-0:/var/log/juju$ ls
audit.log machine-lock.log slow-query.log
juju@controller-0:/var/log/juju$ cat audit.log
juju@controller-0:/var/log/juju$ cat machine-lock.log
juju@controller-0:/var/log/juju$ cat slow-query.log
juju@controller-0:/var/log/juju$