Deprecate Ceilometer Datasource

Ceilometer Datasource has been deprecated since its API has been
deprecated in Ocata cycle. Watcher has supported Ceilometer for some
releases after Ocata to let users migrate to Gnocchi/Monasca datasources.
Since U-release, Ceilometer support will be removed.

Change-Id: I944a5a562ab09a36961eb9b75e9a5144ba0b9ca4

releasenotes/notes/deprecate-ceilometer-datasource-446b0be70fbce28b.yaml

@@ -0,0 +1,7 @@
+---
+deprecations:
+  - |
+    Ceilometer Datasource has been deprecated since its API has been
+    deprecated in Ocata cycle. Watcher has supported Ceilometer for some
+    releases after Ocata to let users migrate to Gnocchi/Monasca datasources.
+    Since Train release, Ceilometer support will be removed.

watcher/conf/ceilometer_client.py

@@ -24,14 +24,32 @@ ceilometer_client = cfg.OptGroup(name='ceilometer_client',
 CEILOMETER_CLIENT_OPTS = [
     cfg.StrOpt('api_version',
                default='2',
+               deprecated_for_removal=True,
+               deprecated_since="1.13.0",
+               deprecated_reason="""
+               Ceilometer API is deprecated since Ocata release.
+               Any related configuration options are deprecated too.
+               """,
                help='Version of Ceilometer API to use in '
                     'ceilometerclient.'),
     cfg.StrOpt('endpoint_type',
                default='internalURL',
+               deprecated_for_removal=True,
+               deprecated_since="1.13.0",
+               deprecated_reason="""
+               Ceilometer API is deprecated since Ocata release.
+               Any related configuration options are deprecated too.
+               """,
                help='Type of endpoint to use in ceilometerclient. '
                     'Supported values: internalURL, publicURL, adminURL. '
                     'The default is internalURL.'),
     cfg.StrOpt('region_name',
+               deprecated_for_removal=True,
+               deprecated_since="1.13.0",
+               deprecated_reason="""
+               Ceilometer API is deprecated since Ocata release.
+               Any related configuration options are deprecated too.
+               """,
                help='Region in Identity service catalog to use for '
                     'communication with the OpenStack service.')]
 

watcher/datasource/ceilometer.py

@@ -19,6 +19,7 @@
 import datetime
 
 from ceilometerclient import exc
+from oslo_log import log
 from oslo_utils import timeutils
 
 from watcher._i18n import _
@@ -27,6 +28,9 @@ from watcher.common import exception
 from watcher.datasource import base
 
 
+LOG = log.getLogger(__name__)
+
+
 class CeilometerHelper(base.DataSourceBase):
 
     NAME = 'ceilometer'
@@ -36,6 +40,9 @@ class CeilometerHelper(base.DataSourceBase):
         """:param osc: an OpenStackClients instance"""
         self.osc = osc if osc else clients.OpenStackClients()
         self.ceilometer = self.osc.ceilometer()
+        LOG.warning("Ceilometer API is deprecated and Ceilometer Datasource "
+                    "module is no longer maintained. We recommend to use "
+                    "Gnocchi instead.")
 
     @staticmethod
     def format_query(user_id, tenant_id, resource_id,