Include zone in GCE instance base name

appengine/gce-backend/instance_group_managers.py

 # Copyright 2016 The LUCI Authors. All rights reserved.
 # Use of this source code is governed under the Apache License, Version 2.0
 # that can be found in the LICENSE file.
 
 """Utilities for operating on instance group managers."""
 
 import collections
 import json
 import logging
 import math
@@ skipping 47 matching lines @@
   """Returns the base name to use when creating an instance group manager.
 
   The base name is suffixed randomly by GCE when naming instances.
 
   Args:
     instance_group_manager: models.InstanceGroupManager.
 
   Returns:
     A string.
   """
-  # <base-name>-<abbreviated-revision>
-  return '%s-%s' % (
+  # <base-name>-<abbreviated-revision>-<zone>
+  # TODO(smut): Ensure this name is < 59 characters because the final
+  # instance name must be < 64 characters and the instance group manager
+  # will add a 5 character random suffix when creating instances.
+  return '%s-%s-%s' % (
       instance_group_manager.key.parent().parent().id(),
       instance_group_manager.key.parent().id()[:8],
+      instance_group_manager.key.id(),
   )
 
 
 @ndb.transactional
 def set_instances(key, keys):
   """Associates the given Instances with the given InstanceGroupManager.
 
   Args:
     key: ndb.Key for a models.InstanceGroupManager entity.
     keys: List of ndb.Keys for models.Instance entities.
@@ skipping 319 matching lines @@
   Returns:
     A dict mapping instance template name to count of instances.
   """
   # Aggregate the number of instances owned by each instance group manager
   # created for each instance template.
   totals = collections.defaultdict(int)
   for instance_group_manager in models.InstanceGroupManager.query():
     instance_template_name = instance_group_manager.key.parent().parent().id()
     totals[instance_template_name] += len(instance_group_manager.instances)
   return totals