Deprecate Ceph deployment

There are now several good tools for deploying Ceph, including Ceph
Ansible and ceph-deploy. Maintaining our own Ceph deployment is a
significant maintenance burden, and we should focus on our core mission
to deploy OpenStack. Given that this is a significant part of kolla
ansible currently we will need a long deprecation period and a migration
path to another tool.

Change-Id: Ic603c85c04d8794580a19f9efaa7a8589565f4f6
Partially-Implements: blueprint remove-ceph

ansible/roles/ceph/tasks/main.yml

 ---
+- name: Warn about deprecation
+  debug:
+    msg: >-
+      Support for deploying Ceph via Kolla Ansible is deprecated. In a future
+      release support for deploying Ceph will be removed from Kolla Ansible. Prior
+      to this we will ensure a migration path to another tool such as Ceph
+      Ansible (http://docs.ceph.com/ceph-ansible/master/>) is available. For new
+      deployments it is recommended to use another tool to deploy Ceph to avoid a
+      future migration. This can be integrated with OpenStack by following the
+      external Ceph guide
+      (https://docs.openstack.org/kolla-ansible/latest/reference/storage/external-ceph-guide.html).
+
 - include_tasks: "{{ kolla_action }}.yml"

doc/source/reference/storage/ceph-guide.rst

 .. _ceph-guide:
 
-===============================
-Ceph - Software Defined Storage
-===============================
+============================================
+Ceph - Software Defined Storage (Deprecated)
+============================================
+
+.. warning::
+   Support for deploying Ceph via Kolla Ansible is deprecated. In a future
+   release support for deploying Ceph will be removed from Kolla Ansible. Prior
+   to this we will ensure a migration path to another tool such as `Ceph
+   Ansible <http://docs.ceph.com/ceph-ansible/master/>`__ is available. For new
+   deployments it is recommended to use another tool to deploy Ceph to avoid a
+   future migration. This can be integrated with OpenStack by following
+   :doc:`external-ceph-guide`.
 
 .. note::
    The out-of-the-box Ceph deployment requires 3 hosts with at least one block

releasenotes/notes/deprecate-ceph-4745da91c7ca5a8e.yaml

+---
+deprecations:
+  - |
+    Deprecates support for deploying Ceph. In a future release support for
+    deploying Ceph will be removed from Kolla Ansible. Prior to this we will
+    ensure a migration path to another tool such as `Ceph Ansible
+    <http://docs.ceph.com/ceph-ansible/master/>`__ is available. For new
+    deployments it is recommended to use another tool to deploy Ceph to avoid a
+    future migration. This can be integrated with OpenStack by following the
+    `external Ceph guide
+    <https://docs.openstack.org/kolla-ansible/latest/reference/storage/external-ceph-guide.html>`__.