Add rsync image deployment spec

Change-Id: Iaac1c6ecf027c05ae352c67a62b90ed90f0b0d27

specs/rsync-image-deployment.rst

@@ -0,0 +1,87 @@
+..
+
+This work is licensed under a Creative Commons Attribution 3.0 Unported License.
+http://creativecommons.org/licenses/by/3.0/legalcode
+
+======================
+Rsync image deployment
+======================
+
+https://blueprints.launchpad.net/bareon/+spec/rsync-image-deployment
+
+Problem description
+===================
+
+Current version of bareon agent deploys an image on block-device level. Thus
+an image can be deployed only to a single partition. Usually the provided
+image is a single partition, however it has dirs like /usr or /var inside,
+that could map to a provided partition schema. To achieve this on the current
+agent we would need to upload multiple images - one per partition.
+
+
+Proposed change
+===============
+
+NOTE: This is a contribution of the feature developed within Cray OpenStack project.
+We are trying to make as minimum changes to existing code as possible.
+
+We propose to use rsync to transfer the image to a baremetal node. Rsync server
+might be an Ironic Conductor (If Ironic is used), or any other calling server
+accessible from the baremetal node. Rsync does file-level copying, thus allows
+to deploy an image across partitions. This would also allow incremental
+image-updates.
+
+To achieve this we are splitting the new kind of driver - deploy driver:
+provision --data-driver <ironic|nailgun> --deploy_driver <swift|rsync>
+
+Deploy driver is basically a manager (on the current code base) converted to a
+driver. Abstract driver would include:
+
+    ::
+
+        @abc.abstractmethod
+        def do_partitioning(self):
+
+        @abc.abstractmethod
+        def do_configdrive(self):
+
+        @abc.abstractmethod
+        def do_copyimage(self):
+
+        @abc.abstractmethod
+        def do_reboot(self):
+
+        @abc.abstractmethod
+        def do_provisioning(self):
+
+And every deploy driver will add their own implementation of these. Currently
+we are moving most of the code to base driver, differentiating only do_copyimage
+method (rsync VS swift).
+
+Alternatives
+------------
+
+None.
+
+Implementation
+==============
+
+Assignee(s)
+-----------
+
+- max_lobur
+
+Milestones
+----------
+
+See blueprint ref above.
+
+Work Items
+----------
+
+- rebase onto Bareon master.
+
+Dependencies
+============
+
+None.