Include zone in GCE instance base name

appengine/gce-backend/instance_group_managers.py

Index: appengine/gce-backend/instance_group_managers.py
diff --git a/appengine/gce-backend/instance_group_managers.py b/appengine/gce-backend/instance_group_managers.py
index 663fd2906cfc038d2cfb2aa76b0bb756757c0d07..10bad9210f1f46608724a9ff6ecb4f14d9e624a0 100644
--- a/appengine/gce-backend/instance_group_managers.py
+++ b/appengine/gce-backend/instance_group_managers.py
@@ -65,10 +65,14 @@ def get_base_name(instance_group_manager):
   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(),
   )

[smut, 2017/08/07 21:56:32]

n.b. This gives us a longest instance name of 42 chars in practice, well below
the limit. But theoretically we need to enforce the limit by rejecting values of
instance_group_manager.key.parent().parent().id() that are too long, which we
should do when validating the config.