constants: confd node roles

confd will return the node role as an integer, which represents one of
the mutually exclusive roles a node can be in.

Signed-off-by: Guido Trotter <ultrotter@google.com>
Reviewed-by: Iustin Pop <iustin@google.com>

lib/constants.py

@@ -628,3 +628,8 @@ CONFD_REQS = frozenset([
   CONFD_REQ_NODE_PIP_BY_INSTANCE_IP,
   ])
 
+(CONFD_NODE_ROLE_MASTER,
+ CONFD_NODE_ROLE_CANDIDATE,
+ CONFD_NODE_ROLE_OFFLINE,
+ CONFD_NODE_ROLE_DRAINED) = range(4)
+