Allow cinder-backup to use ceph

This change updates ceph_client and os_cinder roles to allow
cinder-backup to use ceph.  We also create a new group called
'cinder_backup' which allows us to only retreive the cinder backup key
if cinder-backup is actually in use.

To use, you would simply need to set cinder_service_backup_driver to
cinder.backup.drivers.ceph in your user_variables.yml file.

NOTE: You will need to update your
      /etc/openstack_deploy/env.d/cinder.yml in order for this change
      to execute successfully.

Change-Id: Ib94effa40208bbc8de0f78c5487316be007adcf1
Closes-Bug: #1481787
Implements: blueprint ceph-block-devices
DocImpact

defaults/main.yml

@@ -63,6 +63,7 @@ ceph_mons: []
 # Ceph client usernames for glance and cinder+nova
 glance_ceph_client: glance
 cinder_ceph_client: cinder
+cinder_backup_ceph_client: cinder-backup
 # by default we assume you use rbd for both cinder and nova, and as libvirt
 # needs to access both volumes (cinder) as boot disks (nova) we default to
 # reuse the cinder_ceph_client
@@ -74,6 +75,7 @@ cephkeys_access_group: cephkeys
 openstack_service_system_user: null
 ceph_cinder_service_names:
   - cinder-volume
+  - cinder-backup
 ceph_nova_service_names:
   - nova-compute
 ceph_glance_service_names:

tasks/ceph_auth.yml

@@ -26,7 +26,9 @@
   with_subelements:
   - ceph_components
   - client
-  when: inventory_hostname in groups[item.0.component]
+  when: >
+    inventory_hostname in groups[item.0.component] and
+    (item.0.component != 'cinder_backup' or (cinder_service_backup_program_enabled | bool and cinder_service_backup_driver == 'cinder.backup.drivers.ceph'))
   always_run: true
   changed_when: false
   delegate_to: '{{ ceph_mon_host }}'

vars/main.yml

@@ -31,6 +31,14 @@ ceph_components:
     client:
       - '{{ cinder_ceph_client }}'
     service: '{{ ceph_cinder_service_names }}'
+  - component: cinder_backup
+    package:
+      - ceph # TODO: remove this once http://tracker.ceph.com/issues/11388 is resolved
+      - ceph-common
+      - python-ceph
+    client:
+      - '{{ cinder_backup_ceph_client }}'
+    service: '{{ ceph_cinder_service_names }}'
   - component: nova_compute
     package:
       - libvirt-bin