Local backup files should reflect controller name

[Peter Matulis]

The backup files that get downloaded to the local client by means of the `create-backup` command should, by default, reflect the name of the corresponding controller. Otherwise, backups made on multi-controller setups become indistinguishable. Below, there are two backups for a controller named 'lxd' and one for a controller named 'aws':

-rw-rw-r-- 1 ubuntu ubuntu 56M May 15 19:20 juju-backup-20180515-191942.tar.gz
-rw-rw-r-- 1 ubuntu ubuntu 56M May 15 19:40 juju-backup-20180515-193724.tar.gz
-rw-rw-r-- 1 ubuntu ubuntu 56M May 15 19:58 juju-backup-20180515-195557.tar.gz

The user should not have to rely on the `--filename` option to overcome this confusion. I would expect to see, by default:

-rw-rw-r-- 1 ubuntu ubuntu 56M May 15 19:20 juju-backup-aws-20180515-191942.tar.gz
-rw-rw-r-- 1 ubuntu ubuntu 56M May 15 19:40 juju-backup-lxd-20180515-193724.tar.gz
-rw-rw-r-- 1 ubuntu ubuntu 56M May 15 19:58 juju-backup-lxd-20180515-195557.tar.gz

[Richard Harding (rharding)]

+1, I think that the name should include the controller name, the cloud, and the juju version in the backup file path. I'd not worry about the "juju" part since the it should be clear enough.

jaas-aws-2.2.9-20180515-xxxxxx.tar.gz seems like a good bit of detail to tell backup files apart.

[Heather Lanigan (hmlanigan)]

+1, however there is a --filename flag, for a user specified value, lowering to medium.

[Canonical Juju QA Bot (juju-qa-bot)]

This Medium-priority bug has not been updated in 60 days, so we're marking it Low importance. If you believe this is incorrect, please update the importance.