Add actions for translating between OSD ID and block device, listing OSD block devices, and getting health

[James Hebden]

In order to encourage the use of Juju, rather than SSH'ing to hosts as root, it would be helpful to perform common Ceph operations via Juju actions directly.

I have prepared the following additional actions -
* list-host-osds - lists mounted OSDs for a given unit
* get-health - outputs ceph -s output
* disk-for-osd - returns the block device backing a given OSD
* osd-for-disk - returns the OSD ID (if any) for a given disk

[James Page (james-page)]

New feature so triaging as wishlist and assigning to James as he already has a review up:

https://review.openstack.org/#/c/498718/

[James Page (james-page)]

Please can we target these at the ceph-mon charm rather than ceph (which is deprecated and we'll have a migration story for 18.02 charm release).

[James Hebden (ec0)]

Sure thing - I'll be splitting the action out and targeting ceph-mon and ceph-osd individually.
Should I still make these changes for the ceph charm, or is the officially out of the picture?

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/525024

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/525024
Committed: https://git.openstack.org/cgit/openstack/charm-ceph-mon/commit/?id=001ac4786fc7ac64e3e82c7f922f5b345cca5d55
Submitter: Zuul
Branch: master

commit 001ac4786fc7ac64e3e82c7f922f5b345cca5d55
Author: James Hebden <email address hidden>
Date: Mon Dec 4 12:48:41 2017 +1100

    Add get-health action to the Ceph mon charm

    * get-health - outputs `ceph health` output

    Including unit and functional tests for the above actions.

    Change-Id: Id4c0a89f2068a6f30025d4a165f84ad112b62cf7
    Closes-Bug: #1720099