cmd/juju/storage: "volume list" YAML/JSON format is non-obvious

[Andrew Wilkins]

$ juju bootstrap
$ juju deploy --repository ~/projects/charms local:trusty/storagetest -n2 --storage filesystem=loop
$ juju storage volume list --format=yaml
"1":
  storagetest/0:
    filesystem/0:
      size: 0
      persistent: false
      read-only: false
      volume: 1/0
      status:
        current: pending
        since: 14 Sep 2015 09:32:01+08:00
"2":
  storagetest/1:
    filesystem/1:
      size: 0
      persistent: false
      read-only: false
      volume: 2/1
      status:
        current: pending
        since: 14 Sep 2015 09:32:03+08:00

-----------------------

What are the "1" and "2" IDs? At first you might think they are the volume IDs, but no, they are machine IDs. This is confusing. Storage is meant to be stable from 1.25 onwards, so we have a small window of opportunity to fix this before 1.25 is released.

[Andrew Wilkins (axwalk)]

Proposed format:

-------------------

volumes:
  1/0:
    provider-id: volume-1-0
    storage: filesystem/0
    attachments:
      machines:
        "1":
          device: loop0
          read-only: false
      units:
        storagetest/0:
          machine: "1"
          location: /srv/filesystem/0
    size: 1024
    persistent: false
    status:
      current: attached
      since: 15 Sep 2015 19:13:50+08:00
  2/1:
    provider-id: volume-2-1
    storage: filesystem/1
    attachments:
      machines:
        "2":
          device: loop1
          read-only: false
      units:
        storagetest/1:
          machine: "2"
    size: 1024
    persistent: false
    status:
      current: attached
      since: 15 Sep 2015 19:14:02+08:00