Fix gnt-cluster getmaster on non-master nodes

The current implementation of “gnt-cluster getmaster” doesn't work on
non-master nodes, which is a regression from 1.2. This patch implements
it (again) via ssconf.

Signed-off-by: Iustin Pop <iustin@google.com>
Reviewed-by: Alexander Schreiber <als@google.com>

lib/bootstrap.py

@@ -446,6 +446,22 @@ def MasterFailover():
   return rcode
 
 
+def GetMaster():
+  """Returns the current master node.
+
+  This is a separate function in bootstrap since it's needed by
+  gnt-cluster, and instead of importing directly ssconf, it's better
+  to abstract it in bootstrap, where we do use ssconf in other
+  functions too.
+
+  """
+  sstore = ssconf.SimpleStore()
+
+  old_master, _ = ssconf.GetMasterAndMyself(sstore)
+
+  return old_master
+
+
 def GatherMasterVotes(node_list):
   """Check the agreement on who is the master.
 

scripts/gnt-cluster

@@ -207,7 +207,8 @@ def ShowClusterMaster(opts, args):
   @return: the desired exit code
 
   """
-  ToStdout("%s", GetClient().QueryConfigValues(["master_node"])[0])
+  master = bootstrap.GetMaster()
+  ToStdout(master)
   return 0