Add support for the Ceph storage driver in Gnocchi

Besides implementing the required configuration entries in gnocchi.conf,
this commit also introduces code to create a symlink for the Python
rados library when the Ceph storage driver is chosen by the deployer.

Creation of Ceph Python library symlinks is usually done by the
ceph_client role. However, Gnocchi is different because it needs Ceph
access to be working when the DB sync task is run. Because the venv may
not exist before the os_gnocchi role runs, or because it might be
destroyed and recreated by the role, we need to create the symlink in
the os_gnocchi role itself.

Change-Id: I6b831867079bc24964c323e2784782d4eae30763

defaults/main.yml

@@ -72,6 +72,10 @@ gnocchi_db_sync_options: "--create-legacy-resource-types"
 gnocchi_storage_driver: file
 gnocchi_coordination_url: "mysql://{{ gnocchi_galera_user }}:{{ gnocchi_container_mysql_password }}@{{ gnocchi_galera_address }}/{{ gnocchi_galera_database }}?charset=utf8&timeout=5"
 
+#: Default Ceph parameters
+gnocchi_ceph_pool: "gnocchi"
+gnocchi_ceph_username: "gnocchi"
+
 #: Default Archive Policies
 gnocchi_archive_policies:
   - name: "low"

tasks/gnocchi_ceph_python_libs.yml

@@ -0,0 +1,29 @@
+---
+# Copyright 2014, Rackspace US, Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+- name: Register rados module path
+  command: python -c 'import rados; print rados.__file__'
+  register: rados_module_path
+
+- name: Link rados module into the venv
+  file:
+    src: "{{ rados_module_path.stdout }}"
+    dest: "{{ gnocchi_bin | dirname }}/lib/python2.7/site-packages/{{ rados_module_path.stdout | basename }}"
+    state: link
+    force: "yes"
+  notify:
+    - Restart Apache
+    - Restart Gnocchi API services
+    - Restart Gnocchi extra services

tasks/main.yml

@@ -70,7 +70,14 @@
   tags:
     - gnocchi-install
 
-# N.B. Must occur after identity setup, as this may perform calls to Swift
+- include: gnocchi_ceph_python_libs.yml
+  when:
+    - gnocchi_storage_driver == 'ceph'
+  tags:
+    - gnocchi-install
+
+# N.B. Must occur after identity setup, as this may perform calls to Swift.
+#      Similarly, when using Ceph, must occur after Ceph setup.
 - include: gnocchi_db_setup.yml
   when:
     - inventory_hostname == groups['gnocchi_all'][0]

templates/gnocchi.conf.j2

@@ -70,16 +70,10 @@ swift_container_prefix: gnocchi
 ## Ceph Storage
 ############
 # Ceph pool name to use. (string value)
-#ceph_pool = gnocchi
+ceph_pool = {{ gnocchi_ceph_pool }}
 
-# Ceph username (ie: client.admin). (string value)
-#ceph_username = <None>
-
-# Ceph keyring path. (string value)
-#ceph_keyring = <None>
-
-# Ceph configuration file. (string value)
-#ceph_conffile = /etc/ceph/ceph.conf
+# Ceph username (ie: admin without "client." prefix).
+ceph_username = {{ gnocchi_ceph_username }}
 {% endif %}
 
 [metricd]