Implement subscribe/unsubscribe in nodediscover

This provides a self-evident entry point from
CLI to extending the discovery to
affluent switches that support it.

This function will work with newer affluent
and Lenovo XCC2 systems.

confluent_client/bin/nodediscover

@@ -50,7 +50,13 @@ columnmapping = {
 }
 #TODO: add chassis uuid
 
-
+def subscribe_discovery(options, session, subscribe):
+    keyn = 'subscribe' if subscribe else 'unsubscribe'
+    payload = {keyn: options.node}
+    for rsp in session.update('/discovery/subscription', payload):
+        if 'status' in rsp:
+            print(rsp['status'])
+    
 def print_disco(options, session, currmac, outhandler, columns):
     procinfo = {}
     for tmpinfo in session.read('/discovery/by-mac/{0}'.format(currmac)):
@@ -361,7 +367,7 @@ def main():
     parser.add_option('-o', '--order', dest='order',
                       help='Order output by given field', metavar='ORDER')
     (options, args) = parser.parse_args()
-    if len(args) == 0 or args[0] not in ('list', 'assign', 'reassign', 'rescan', 'clear'):
+    if len(args) == 0 or args[0] not in ('list', 'assign', 'reassign', 'rescan', 'clear', 'subscribe', 'unsubscribe'):
         parser.print_help()
         sys.exit(1)
     session = client.Command()
@@ -373,6 +379,10 @@ def main():
         assign_discovery(options, session)
     if args[0] == 'reassign':
         assign_discovery(options, session, False)
+    if args[0] == 'subscribe':
+        subscribe_discovery(options, session, True)
+    if args[0] == 'unsubscribe':
+        subscribe_discovery(options, session, False)
     if args[0] == 'rescan':
         blocking_scan(session)
         print("Rescan complete")

confluent_client/doc/man/nodediscover.ronn

@@ -5,9 +5,11 @@ nodediscover(8)  -- List or manage confluent node discovery
 
 `nodediscover rescan`  
 `nodediscover [options] list`  
-`nodediscover [options] assign`
-`nodediscover [options] rescan`
-`nodediscover [options] clear`
+`nodediscover [options] assign`  
+`nodediscover [options] rescan`  
+`nodediscover [options] clear`  
+`nodediscover [options] subscribe`  
+`nodediscover [options] unsubscribe`  
 
 ## DESCRIPTION
 
@@ -35,6 +37,9 @@ scan is the best approach to catch something that appears to be missing.
 **nodedsicover clear** requests the server forget about a selection of
 detected device.  It takes the same arguments as **nodediscover list**.
 
+**nodediscover subscribe** and **unsubscribe** instructs confluent to subscribe to or
+unsubscribe from the designated (-n) node running affluent with system discovery support.
+
 ## CSV FORMAT
 
 The CSV format used by nodediscover consists of one header describing the