Implement 'unset' in confetty interactive cli.

Provide a means to clear node specific settings so that inheritance can be restored.
In JSON, send a null as a value for a parameter instead of a string or 'object'.

bin/confetty

@@ -70,6 +70,7 @@ valid_commands = [
     'cd',
     'show',
     'set',
+    'unset',
     'create',
 ]
 
@@ -234,9 +235,24 @@ def do_command(command, server):
         return
     elif argv[0] == 'set':
         setvalues(argv[1:])
+    elif argv[0] in ('unset', 'clear'):
+        clearvalues(argv[1], argv[2:])
     else:
         sys.stderr.write("%s: command not found...\n" % argv[0])
 
+
+def clearvalues(resource, attribs):
+    targpath = fullpath_target(resource)
+    keydata = {}
+    for attrib in attribs:
+        keydata[attrib] = None
+    for res in send_request('update', targpath, server, keydata):
+        if 'error' in res:
+            if 'errorcode' in res:
+                exitcode = res['errorcode']
+            sys.stderr.write('Error: ' + res['error'] + '\n')
+
+
 def setvalues(attribs):
     if '=' in attribs[0]:  # going straight to attribute
         resource = attribs[0][:attribs[0].index("=")]

plugins/configuration/attributes.py

@@ -125,12 +125,20 @@ def update_nodegroup(group, element, configmanager, inputdata):
     except ValueError:
         raise exc.InvalidArgumentException()
     return retrieve_nodegroup(group, element, configmanager, inputdata)
-    
+
 def update_nodes(nodes, element, configmanager, inputdata):
     updatedict = {}
     for node in nodes:
         updatenode = inputdata.get_attributes(node)
+        clearattribs = []
         if updatenode:
+            for attrib in updatenode.iterkeys():
+                if updatenode[attrib] is None:
+                    clearattribs.append(attrib)
+            if len(clearattribs) > 0:
+                for attrib in clearattribs:
+                    del updatenode[attrib]
+                configmanager.clear_node_attributes([node], clearattribs)
             updatedict[node] = updatenode
     try:
         configmanager.set_node_attributes(updatedict)