rbd: expose pool stats summary tool

[dillaman]

• References tracker ticket
• Updates documentation if necessary
• Includes tests for new functionality or reproducer for bug

[trociny]

@dillaman It looks like you squshed wrong commits.

[dillaman]

@trociny Indeed -- thx and fixed.

[dillaman]

@trociny bit the bullet and went w/ your original suggestion to have dynamic stat querying.

[trociny]

lgtm

[trociny]

When running all pybind tests it fails with:

======================================================================
FAIL: test_rbd.test_pool_stats
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/nose/case.py", line 197, in runTest
    self.test(*self.arg)
  File "/home/mgolub/ceph/ceph.ci/src/test/pybind/test_rbd.py", line 119, in _require_new_format
    return fn(*args, **kwargs)
  File "/home/mgolub/ceph/ceph.ci/src/test/pybind/test_rbd.py", line 397, in test_pool_stats
    eq(stats['trash_count'], 0)
AssertionError: 1L != 0

Which is due to TestTrash.test_remove_denied not doing necessary cleanup. Anyway, probably a good idea to additionally run rbd.pool_stats_get before creating the images to make sure the pool is empty?

And you need to do the images cleanup too, because after fixing TestTrash.test_remove_denied by adding
RBD().trash_remove(ioctx, image_id, True) I start to observe:

======================================================================
FAIL: test_rbd.test_list_empty
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/nose/case.py", line 197, in runTest
    self.test(*self.arg)
  File "/ssd/ceph/ceph.ci/src/test/pybind/test_rbd.py", line 314, in test_list_empty
    eq([], RBD().list(ioctx))
AssertionError: [] != [u'image175', u'image176', u'image177', u'image178']

[dillaman]

@trociny Sorry about that -- should be better now