Expand the description of extra_capabilities

The existing description of extra_capabilities was a bit terse,
meaning deployers couldn't easily gauge the power of this option.
This patch expands the textual description using information from
the blueprint and original commit message, so it can be picked
up automatically by the documentation.

Change-Id: Iac2b6d8a3ce4875a8c1d9874dd7f0e4cf7c435c0
Closes-Bug: 1288044

diff --git a/cinder/volume/manager.py b/cinder/volume/manager.py
index a6a6f9a9e0ebff7ba67f74f45c18f6a80864693c..6c51940098c9a8e8d93fe3733e2ed2191f6dd1c9 100644 (file)
--- a/cinder/volume/manager.py
+++ b/cinder/volume/manager.py
@@ -91,7 +91,13 @@ volume_manager_opts = [
     cfg.StrOpt('extra_capabilities',
                default='{}',
                help='User defined capabilities, a JSON formatted string '
-                    'specifying key/value pairs.'),
+                    'specifying key/value pairs. The key/value pairs can '
+                    'be used by the CapabilitiesFilter to select between '
+                    'backends when requests specify volume types. For '
+                    'example, specifying a service level or the geographical '
+                    'location of a backend, then creating a volume type to '
+                    'allow the user to select by these different '
+                    'properties.'),
 ]
 
 CONF = cfg.CONF