Add flag argument to 'cinder-manage config list'

Unlike other cinder-manage 'list' commands the 'config list'
option doesn't allow users to specify a filter to limit
the output.  This commit adds the ability to specify
the flag the user wishes to display.

If no flag is specified the default behavior is still to
display all the configured flags.  If the flag requested
is not found, cinder-manage reports that the flag was not
found.

(fixes bug 1187137)

Change-Id: I698f4c06d7e93217d8f307a880e0ae40711151c2

bin/cinder-manage

@@ -450,9 +450,21 @@ class ConfigCommands(object):
     def __init__(self):
         pass
 
-    def list(self):
-        for key, value in CONF.iteritems():
-            if value is not None:
+    @args('param', nargs='?', default=None,
+          help='Configuration parameter to display (default: %(default)s)')
+    def list(self, param=None):
+        """List parameters configured for cinder.
+
+        Lists all parameters configured for cinder unless an optional argument
+        is specified.  If the parameter is specified we only print the
+        requested parameter.  If the parameter is not found an appropriate
+        error is produced by .get*().
+        """
+        param = param and param.strip()
+        if param:
+            print '%s = %s' % (param, CONF.get(param))
+        else:
+            for key, value in CONF.iteritems():
                 print '%s = %s' % (key, value)
 
 

doc/source/man/cinder-manage.rst

@@ -157,9 +157,9 @@ Cinder Storage Management
 Cinder Config
 ~~~~~~~~~~~~~
 
-``cinder-manage config list``
+``cinder-manage config list [<param>]``
 
-    Displays the current configuration parameters (options) for Cinder.
+    Displays the current configuration parameters (options) for Cinder. The optional flag parameter may be used to display the configuration of one parameter.
 
 FILES
 =====