[root@centos juju]# tail -f machine-0.log 
2017-03-30 17:35:33 ERROR juju.worker.peergrouper worker.go:192 cannot set replicaset: exception: hosts cannot switch between localhost and hostname
2017-03-30 17:35:36 ERROR juju.worker.proxyupdater proxyupdater.go:164 can't connect to the local LXD server: LXD socket not found; is LXD installed & running?

Please install LXD by running:
	$ sudo apt-get install lxd
and then configure it with:
	$ newgrp lxd
	$ lxd init

2017-03-30 17:35:37 ERROR juju.worker.peergrouper worker.go:192 cannot set replicaset: exception: hosts cannot switch between localhost and hostname
2017-03-30 17:35:45 ERROR juju.worker.peergrouper worker.go:192 cannot set replicaset: exception: hosts cannot switch between localhost and hostname
2017-03-30 17:36:02 ERROR juju.worker.peergrouper worker.go:192 cannot set replicaset: exception: hosts cannot switch between localhost and hostname