Count configured minimum and maximum numbers of instances

appengine/gce-backend/config.py

Index: appengine/gce-backend/config.py
diff --git a/appengine/gce-backend/config.py b/appengine/gce-backend/config.py
index a64883ac26024e752cac0cf4ca361c4a9bee60aa..cde35e0b21682eedf9f2961206a8c8fa24132628 100644
--- a/appengine/gce-backend/config.py
+++ b/appengine/gce-backend/config.py
@@ -65,6 +65,22 @@ class Configuration(datastore_utils.config.GlobalConfig):
     return template_cfg, manager_cfg
 
 
+def count_instances():
+  """Counts the numbers of instances configured by each instance template.
+
+  Returns:
+    A dict mapping instance template name to a list of (min, max).
+  """
+  # Aggregate the numbers of instances configured in each instance group manager
+  # created for each instance template.
+  totals = collections.defaultdict(lambda: [0, 0])
+  _, manager_cfg = Configuration.load()
+  for manager in manager_cfg.managers:
+    totals[manager.template_base_name][0] += manager.minimum_size
+    totals[manager.template_base_name][1] += manager.maximum_size
+  return totals
+
+
 def update_template_configs():
   """Updates the local template configuration from the config service.