Merge "Add batching to ResourceGroup"

specs/liberty/resource-group-batching.rst

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+..
+ This work is licensed under a Creative Commons Attribution 3.0 Unported
+ License.
+
+ http://creativecommons.org/licenses/by/3.0/legalcode
+
+====================================================
+Implement batch create and update for resource group
+====================================================
+
+https://blueprints.launchpad.net/heat/+spec/resource-group-batching
+
+Add possibility to create and update resources in batches
+
+Problem description
+===================
+
+Heat doesn't allow to create resources in batches which can lead
+to unnecessary high load of the cloud for large number of resources.
+In particular nova can fail while deploying large Sahara clusters
+because of tons of simultaneous requests to create/update VMs and
+polling those resources for status.
+Also Heat partially support batch update (only for AutoscalingGroup)
+
+Proposed change
+===============
+
+Add batching_policy property to ResourceGroup with similar to
+rolling_update structure::
+
+    res_group:
+      type: OS::Heat:ResourceGroup
+       properties:
+         count: 5
+         ...
+         batching_policy:
+           min_in_service:1
+           max_batch_size: 2
+           pause_time: 10
+           batch_actions: ['CREATE', 'UPDATE_EXISTING', 'UPDATE']
+        ...
+
+Where:
+
+`max_batch_size`, `pause_time`, `min_in_service` has the same meaning as
+in rolling_update with one exception that `min_in_service` can't be applied
+to batch `CREATE` action and will be ignored.
+
+``batch_actions`` is actions that will be batched, with the following available
+options:
+
+`CREATE`: apply batching on stack creation i.e. add resources in sequence by
+`max_batch_size` resources at every batch, possible except for the last one.
+
+`UPDATE_EXISTING`: exactly the same thing as rolling update
+
+`UPDATE`: regular update, existing resources will updated in batches and if it
+is needed to add some count of resources they will be added in bathes too.
+
+It is proposed to make old rolling_update property deprecated in favour of
+batching_policy as batching_policy has wider possibilities including old
+rolling_update.
+
+Alternatives
+------------
+
+None
+
+Implementation
+==============
+
+Assignee(s)
+-----------
+
+ochuprykov
+
+Milestones
+----------
+
+Target Milestone for completion:
+  Liberty-2
+
+Work Items
+----------
+
+* Add batching_policy property to ResourceGroup
+* Add required additional unit and functional test cases
+
+Dependencies
+============
+
+None