Add standardize-nova-image blueprint

Adds blueprint specification for standardizing the nova.image module
into nova.image.api in the same way that nova.network.api works.

Change-Id: I17b3dc79c0a2286f019506e4869b23f03e15a0e7

specs/juno/standardize-nova-image.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
+
+======================
+Standardize Nova Image
+======================
+
+https://blueprints.launchpad.net/nova/+spec/standardize-nova-image
+
+Standardize Nova's nova.image module to work like nova.network.api
+and nova.volume.cinder.
+
+Problem description
+===================
+
+For some reason, nova.image does things differently than nova.volume and
+nova.network. Instead of nova.compute.manager instantiating a
+self.image_api object, like it does for self.network_api and
+self.volume_api, the compute manager calls an obtuse collection of
+nova.image.glance module calls.
+
+This blueprint is around the work to make a new nova.image.api module
+and have it called like other submodule "internal APIs" in Nova.
+
+Proposed change
+===============
+
+A new nova.image.api module shall be created, following in the style
+of nova.network.api and nova.volume.cinder. There will be an API class
+in the nova.image.api module that follows identical conventions as the
+nova.volume.cinder.API class, with methods for listing (get_all), showing
+(get), creating (create), updating (update), and removing (delete)
+images from the backend image store. There will be a nova.image.driver
+module with a base driver class.
+
+The nova.image.glance module will be updated to subclass the base driver
+class.
+
+Alternatives
+------------
+
+There is a series of patches in review up for Nova that tries to add
+support for Glance's V2 API operations:
+
+https://review.openstack.org/#/q/status:open+project:openstack/nova+branch:master+topic:bp/use-glance-v2-api,n,z
+
+Unfortunately, I believe this patch series further muddies the image
+service inside Nova instead of making it cleaner and standardized with
+the rest of Nova's external API interfaces.
+
+The idea of this blueprint is to lay a good foundation for future V2
+Glance API work by first standardizing the image API inside of Nova.
+
+Data model impact
+-----------------
+None
+
+REST API impact
+---------------
+None
+
+Security impact
+---------------
+None
+
+Notifications impact
+--------------------
+None
+
+Other end user impact
+---------------------
+None
+
+Performance Impact
+------------------
+None
+
+Other deployer impact
+---------------------
+None
+
+Developer impact
+----------------
+
+See above link to Eddie Sheffield's patch series that would be affected by the
+code in this blueprint. Hopefully, however, once the image API is brought in
+line with the other internal-to-external Nova APIs, the work on V2 Glance API
+should be quite a bit easier.
+
+Implementation
+==============
+
+Assignee(s)
+-----------
+
+Primary assignee:
+  jaypipes
+
+Work Items
+----------
+
+ * Create the nova.image.api module that instantiates a driver
+ * Create the base image driver class, modeling after the new
+   nova.network.driver class created by the refactor-network-api blueprint
+   code.
+ * Move the existing glance code into a subclassed driver
+
+Dependencies
+============
+None
+
+Testing
+=======
+None
+
+Documentation Impact
+====================
+None
+
+References
+==========
+None