SimpleConfigReader: add IP address lookup helpers

Add the following functions to SimpleConfigReader:
GetInstanceByIp, nic ip -> instance name
GetNodePrimaryIp, node name -> node primary ip
GetInstancePrimaryNode, instance name -> primary node

For the first one we precalculate the _ip_to_instance, so we don't have
to loop over all instances for each query.

Signed-off-by: Guido Trotter <ultrotter@google.com>
Reviewed-by: Michael Hanselmann <hansmi@google.com>

lib/ssconf.py

@@ -95,6 +95,13 @@ class SimpleConfigReader(object):
       raise errors.ConfigurationError("Cannot load config file %s: %s" %
                                       (self._file_name, err))
 
+    self._ip_to_instance = {}
+    for iname in self._config_data['instances']:
+      instance = self._config_data['instances'][iname]
+      for nic in instance['nics']:
+        if 'ip' in nic and nic['ip']:
+          self._ip_to_instance[nic['ip']] = iname
+
     return True
 
   # Clients can request a reload of the config file, so we export our internal
@@ -148,6 +155,37 @@ class SimpleConfigReader(object):
     offline = self._config_data["nodes"][node]["offline"]
     return master_candidate, drained, offline
 
+  def GetInstanceByIp(self, ip):
+    if ip not in self._ip_to_instance:
+      return None
+    return self._ip_to_instance[ip]
+
+  def GetNodePrimaryIp(self, node):
+    """Get a node's primary ip
+
+    @type node: string
+    @param node: node name
+    @rtype: string, or None
+    @return: node's primary ip, or None if no such node
+
+    """
+    if node not in self._config_data["nodes"]:
+      return None
+    return self._config_data["nodes"][node]["primary_ip"]
+
+  def GetInstancePrimaryNode(self, instance):
+    """Get an instance's primary node
+
+    @type instance: string
+    @param instance: instance name
+    @rtype: string, or None
+    @return: primary node, or None if no such instance
+
+    """
+    if instance not in self._config_data["instances"]:
+      return None
+    return self._config_data["instances"][instance]["primary_node"]
+
 
 class SimpleStore(object):
   """Interface to static cluster data.