Specification for allowing Kolla Ceph to deploy bluestore OSDs

Describes the proposed approach to introduce Ceph blustore[1] OSDs
in Kolla.

[1] http://docs.ceph.com/docs/master/

Partially-Implements: blueprint kolla-ceph-bluestore

Change-Id: I388e720270f9971900fe56c38d52a8cdf563e7a2
Signed-off-by: Tone Zhang <tone.zhang@arm.com>

specs/kolla-ceph-bluestore.rst

@@ -0,0 +1,103 @@
+=========================================
+Allow Kolla Ceph to deploy bluestore OSDs
+=========================================
+
+https://blueprints.launchpad.net/kolla/+spec/kolla-ceph-bluestore
+
+Kolla Ceph currently only supports filestore. In Queens release, the version of
+Ceph is Luminous, and the bluestore is the default store type. See [1].
+
+This spec suggests to allow Kolla Ceph to deploy bluestore OSDs by default, and
+make the store type configurable.
+
+Problem description
+===================
+In Ceph Luminous, the bluestore is the default store type when deploy Ceph. As
+Kolla Ceph currently only supports filestore, so it is not aligned with Ceph
+default behaviour. We should support both filestore and bluestore in Kolla
+Ceph.
+
+In Ceph bluestore, there are up to three partitions belong to one Ceph OSD,
+they are used for block, block.wal and block.db. We should support to activate
+the three partitions when deploy Ceph bluestore OSDs if the corresponding
+labels are defined and associated with the physical devices.
+
+Use cases
+---------
+1. Deploy Kolla Ceph and enable bluestore as default (the default value of
+the parameter ``ceph_osd_store_type`` is ``bluestore`` in
+``/etc/kolla/globals.yml``)
+2. Deploy Kolla Ceph and enable filestore in the configuration file (change
+the value of the parameter ``ceph_osd_store_type`` to ``filestore`` in
+``/etc/kolla/globals.yml``)
+
+Proposed change
+===============
+
+Exposing the store type
+-----------------------
+Define new configuration parameter ``ceph_osd_store_type`` in Kolla
+configuration file ``/etc/kolla/globals.yml`` to indicate the store type used
+in Kolla Ceph.
+
+Existing Kolla Containers
+-------------------------
+In the existing Ceph-OSD container, the OSD store type will be handled when
+start the Ceph OSD container. If any one label of block, block.wal or
+block.db is defined, activate the Ceph OSD according to the configuration. If
+there is no label associated with block.wal and block.db, then activate Ceph
+OSD in one docker volume.
+
+Indicate block, block.wal and block.db belonging to the same Ceph OSD according
+to the partition labels, it keeps the same method used in Kolla Ceph filestore.
+* ``KOLLA_CEPH_OSD_BOOSTRAP_BS_xxx`` is the block volume label of one bluestore
+OSD
+* ``KOLLA_CEPH_OSD_BOOSTRAP_BS_W_xxx`` is the block.wal volume label of one
+bluestore OSD
+* ``KOLLA_CEPH_OSD_BOOSTRAP_BS_D_xxx`` is the block.db volume label of one
+bluestore OSD
+Here, ``xxx`` is the suffix used to indicate the above volumes belong to the
+same Ceph OSD.
+
+Security Impact
+---------------
+There is no security impact introduced.
+
+Performance Impact
+------------------
+There is no performance imapct introduced.
+
+Implementation
+==============
+
+Assignee(s)
+-----------
+  Tone Zhang (tone_zrt)
+
+Milestones
+----------
+Target Milestone for completion: Rocky
+
+Work Items
+----------
+1. Expose OSD store type in Kolla configuration file
+2. Check disk partition labels when start Ceph-OSD container if the store
+type is bluestore
+3. Modify the Ceph-OSD starting script to support bluestore
+4. Active block, block.wal and block.db configurable in Ceph bluestore OSD
+
+Testing
+=======
+The existing gate checks will be used to ensure Ceph bluestore OSD
+successful deployment.
+
+Documentation Impact
+====================
+The reference page ``Ceph in Kolla`` [2] should be updated.
+The page will document how to change the Ceph store type and how to deploy Ceph
+bluestore OSD.
+
+References
+==========
+[1] http://docs.ceph.com/docs/master/
+[2] https://docs.openstack.org/kolla-ansible/latest/reference/ceph-guide.html