Merge "Spec: remove Heat"

doc/source/specs/remove_heat.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
+
+===========
+Remove Heat
+===========
+
+https://blueprints.launchpad.net/karbor/+spec/remove-heat
+
+Problem description
+===================
+
+As it stands, Karbor uses Heat to restore the resources which had been protected
+before. Although it works well, some disadvantages are still very obvious. Firstly,
+Karbor just uses a fraction of functions which Heat supplies so that it seems too
+heavy to Karbor. Second, for developers of protection plugins, they prefer implementing
+the restoration of resources by protection plugin itself to Heat. Third, both Karbor
+and Heat should be deployed at the time, which will add more workload. Last, from
+the point of view of implementation, Heat stack runs after all the protection
+plugins' hooks which breaks the hook definition of 'on_complete'.
+
+
+Use Cases
+=========
+
+* Implement restoration of resources by protection plugins themselves.
+* No longer deploy Heat.
+
+
+Proposed change
+===============
+
+There are two main changes. First one, the implementation of restore should be
+refactored for all protection plugins. At present, there are 4 kinds of plugins
+in Karbor and the new restore methods are described as below respectively.
+
+* volume plugin
+  It will create a new volume with original backup volume.
+
+* image plugin
+  It will create a new image and upload the original backup data to it.
+
+* network plugin
+  It will create a new network with original backup network.
+
+* vm plugin
+  It is a bit more complex, because it has several child resources, such as volume, ip.
+  First, it should create a new vm. Second, add the child resources to it, such as
+  attach the volumes, set the ip.
+
+Another change is updating the deployment scripts which will no longer install Heat.
+
+
+Alternatives
+------------
+
+None
+
+Data model impact
+-----------------
+
+None
+
+REST API impact
+---------------
+
+None
+
+Security impact
+---------------
+
+None
+
+Notifications impact
+--------------------
+
+None
+
+Other end user impact
+---------------------
+
+None
+
+Performance Impact
+------------------
+
+There should be no loss on performance, because it does same work as Heat actually.
+
+Other deployer impact
+---------------------
+
+None
+
+Developer impact
+----------------
+
+The developers of protection plugins should know these changes.
+
+
+Implementation
+==============
+
+Assignee(s)
+-----------
+
+
+Work Items
+----------
+
+* refactor all protection plugins
+* update the deployment scripts
+* update the document of developing protection plugin
+
+Dependencies
+============
+
+None
+
+Testing
+=======
+
+Unit and fullstack tests in Karbor.
+
+
+Documentation Impact
+====================
+
+Documents about how to develop protection plugin should be updated also.
+
+References
+==========
+
+None