Don't throw exception when missing metrics

When querying data from datasource, it's possible to miss some data.
In this case if we throw an exception, Audit will failed because of
the exception. We should remove the exception and give the decision
to the strategy.

Change-Id: I1b0e6b78b3bba4df9ba16e093b3910aab1de922e
Closes-Bug: #1847434
can not cherry picke from master because of code refactoring

watcher/datasource/ceilometer.py

@@ -136,15 +136,15 @@ class CeilometerHelper(base.DataSourceBase):
             self.osc.reset_clients()
             self.ceilometer = self.osc.ceilometer()
             return f(*args, **kargs)
-        except Exception:
-            raise
+        except Exception as e:
+            LOG.exception(e)
 
     def check_availability(self):
-        try:
-            self.query_retry(self.ceilometer.resources.list)
-        except Exception:
+        status = self.query_retry(self.ceilometer.resources.list)
+        if status:
+            return 'available'
+        else:
             return 'not available'
-        return 'available'
 
     def query_sample(self, meter_name, query, limit=1):
         return self.query_retry(f=self.ceilometer.samples.list,
@@ -162,9 +162,8 @@ class CeilometerHelper(base.DataSourceBase):
 
     def list_metrics(self):
         """List the user's meters."""
-        try:
-            meters = self.query_retry(f=self.ceilometer.meters.list)
-        except Exception:
+        meters = self.query_retry(f=self.ceilometer.meters.list)
+        if not meters:
             return set()
         else:
             return meters

watcher/datasource/gnocchi.py

@@ -24,7 +24,6 @@ from oslo_config import cfg
 from oslo_log import log
 
 from watcher.common import clients
-from watcher.common import exception
 from watcher.common import utils as common_utils
 from watcher.datasource import base
 
@@ -60,20 +59,18 @@ class GnocchiHelper(base.DataSourceBase):
             except Exception as e:
                 LOG.exception(e)
                 time.sleep(CONF.gnocchi_client.query_timeout)
-        raise exception.DataSourceNotAvailable(datasource='gnocchi')
 
     def check_availability(self):
-        try:
-            self.query_retry(self.gnocchi.status.get)
-        except Exception:
+        status = self.query_retry(self.gnocchi.status.get)
+        if status:
+            return 'available'
+        else:
             return 'not available'
-        return 'available'
 
     def list_metrics(self):
         """List the user's meters."""
-        try:
-            response = self.query_retry(f=self.gnocchi.metric.list)
-        except Exception:
+        response = self.query_retry(f=self.gnocchi.metric.list)
+        if not response:
             return set()
         else:
             return set([metric['name'] for metric in response])
@@ -106,8 +103,9 @@ class GnocchiHelper(base.DataSourceBase):
                 f=self.gnocchi.resource.search, **kwargs)
 
             if not resources:
-                raise exception.ResourceNotFound(name='gnocchi',
-                                                 id=resource_id)
+                LOG.warning("The {0} resource {1} could not be "
+                            "found".format(self.NAME, resource_id))
+                return
 
             resource_id = resources[0]['id']
 

watcher/datasource/monasca.py

@@ -19,11 +19,14 @@
 import datetime
 
 from monascaclient import exc
+from oslo_log import log
 
 from watcher.common import clients
 from watcher.common import exception
 from watcher.datasource import base
 
+LOG = log.getLogger(__name__)
+
 
 class MonascaHelper(base.DataSourceBase):
 
@@ -53,8 +56,8 @@ class MonascaHelper(base.DataSourceBase):
             self.osc.reset_clients()
             self.monasca = self.osc.monasca()
             return f(*args, **kwargs)
-        except Exception:
-            raise
+        except Exception as e:
+            LOG.exception(e)
 
     def _format_time_params(self, start_time, end_time, period):
         """Format time-related params to the correct Monasca format
@@ -78,11 +81,11 @@ class MonascaHelper(base.DataSourceBase):
         return start_timestamp, end_timestamp, period
 
     def check_availability(self):
-        try:
-            self.query_retry(self.monasca.metrics.list)
-        except Exception:
+        status = self.query_retry(self.monasca.metrics.list)
+        if status:
+            return 'available'
+        else:
             return 'not available'
-        return 'available'
 
     def list_metrics(self):
         # TODO(alexchadin): this method should be implemented in accordance to