From 0112415f66ce902786076c0238dcded38512ff28 Mon Sep 17 00:00:00 2001
From: Mehdi Abaakouk <sileht@sileht.net>
Date: Thu, 6 Oct 2016 17:13:43 +0200
Subject: [PATCH] Handle case where sample-api is disabled

This change forbids the creation of threshold alarm if ceilometer
sample-api is disabled.

And logs warning if alarm created before try to use it.

Change-Id: I59861e0d78b120f194c34cc21c4b5e806f22b970
---
 .../controllers/v2/alarm_rules/threshold.py   | 49 ++++++++++++++++++-
 aodh/evaluator/threshold.py                   | 10 +++-
 2 files changed, 55 insertions(+), 4 deletions(-)

diff --git a/aodh/api/controllers/v2/alarm_rules/threshold.py b/aodh/api/controllers/v2/alarm_rules/threshold.py
index 168f7a7ba..880286b34 100644
--- a/aodh/api/controllers/v2/alarm_rules/threshold.py
+++ b/aodh/api/controllers/v2/alarm_rules/threshold.py
@@ -11,14 +11,21 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 
+from ceilometerclient import client as ceiloclient
+from ceilometerclient import exc as ceiloexc
+from oslo_log import log
+import pecan
 import wsme
 from wsme import types as wtypes
 
 from aodh.api.controllers.v2 import base
 from aodh.api.controllers.v2 import utils as v2_utils
 from aodh.i18n import _
+from aodh import keystone_client
 from aodh import storage
 
+LOG = log.getLogger(__name__)
+
 
 class AlarmThresholdRule(base.AlarmRule):
     """Alarm Threshold Rule
@@ -57,10 +64,47 @@ class AlarmThresholdRule(base.AlarmRule):
     exclude_outliers = wsme.wsattr(bool, default=False)
     "Whether datapoints with anomalously low sample counts are excluded"
 
+    ceilometer_sample_api_is_supported = None
+
     def __init__(self, query=None, **kwargs):
         query = [base.Query(**q) for q in query] if query else []
         super(AlarmThresholdRule, self).__init__(query=query, **kwargs)
 
+    @classmethod
+    def _check_ceilometer_sample_api(cls):
+        # Check it only once
+        if cls.ceilometer_sample_api_is_supported is None:
+
+            auth_config = pecan.request.cfg.service_credentials
+            client = ceiloclient.get_client(
+                version=2,
+                session=keystone_client.get_session(pecan.request.cfg),
+                # ceiloclient adapter options
+                region_name=auth_config.region_name,
+                interface=auth_config.interface,
+            )
+            try:
+                client.statistics.list(
+                    meter_name="idontthinkthatexistsbutwhatever")
+            except Exception as e:
+                if isinstance(e, ceiloexc.HTTPException):
+                    if e.code == 410:
+                        cls.ceilometer_sample_api_is_supported = False
+                    elif e.code < 500:
+                        cls.ceilometer_sample_api_is_supported = True
+                    else:
+                        raise
+                else:
+                    raise
+            else:
+                # I don't think this meter can exists but how known
+                cls.ceilometer_sample_api_is_supported = True
+
+        if cls.ceilometer_sample_api_is_supported is False:
+            raise base.ClientSideError(
+                "This telemetry installation is not configured to support"
+                "alarm of type 'threshold")
+
     @staticmethod
     def validate(threshold_rule):
         # note(sileht): wsme default doesn't work in some case
@@ -77,8 +121,9 @@ class AlarmThresholdRule(base.AlarmRule):
                                 allow_timestamps=False)
         return threshold_rule
 
-    @staticmethod
-    def validate_alarm(alarm):
+    @classmethod
+    def validate_alarm(cls, alarm):
+        cls._check_ceilometer_sample_api()
         # ensure an implicit constraint on project_id is added to
         # the query if not already present
         alarm.threshold_rule.query = v2_utils.sanitize_query(
diff --git a/aodh/evaluator/threshold.py b/aodh/evaluator/threshold.py
index 20516b362..ffe6b68bc 100644
--- a/aodh/evaluator/threshold.py
+++ b/aodh/evaluator/threshold.py
@@ -19,6 +19,7 @@ import operator
 import six
 
 from ceilometerclient import client as ceiloclient
+from ceilometerclient import exc as ceiloexc
 from oslo_config import cfg
 from oslo_log import log
 from oslo_utils import timeutils
@@ -126,8 +127,13 @@ class ThresholdEvaluator(evaluator.Evaluator):
             return self.cm_client.statistics.list(
                 meter_name=rule['meter_name'], q=query,
                 period=rule['period'])
-        except Exception:
-            LOG.exception(_('alarm stats retrieval failed'))
+        except Exception as e:
+            if isinstance(e, ceiloexc.HTTPException) and e.code == 410:
+                LOG.warning("This telemetry installation is not configured to "
+                            "support alarm of type 'threshold', they should "
+                            "be disabled or removed.")
+            else:
+                LOG.exception(_('alarm stats retrieval failed'))
             return []
 
     @staticmethod