From 6404ec1569ab9cd71a01738390157fc5d7ab1796 Mon Sep 17 00:00:00 2001
From: Luka Peschke <luka.peschke@objectif-libre.com>
Date: Thu, 21 Mar 2019 12:19:51 +0100
Subject: [PATCH] Skip a cycle instead of retrying if a metric is not found in
 gnocchi

In case a metric is not found in gnocchi, return nothing instead of retrying.
The metric is unlikely to be available during the next collection cycle.

Change-Id: I4b954b146b800255554449bb19eb4bed3cb87dd4
---
 cloudkitty/collector/gnocchi.py               | 27 ++++++++++++++-----
 .../notes/add-scope-key-58135c2a5c6dae68.yaml |  2 +-
 ...f-nonexistent-metric-ba56a671e68f5bf5.yaml |  6 +++++
 3 files changed, 27 insertions(+), 8 deletions(-)
 create mode 100644 releasenotes/notes/skip-period-if-nonexistent-metric-ba56a671e68f5bf5.yaml

diff --git a/cloudkitty/collector/gnocchi.py b/cloudkitty/collector/gnocchi.py
index ceedaa7d..38751817 100644
--- a/cloudkitty/collector/gnocchi.py
+++ b/cloudkitty/collector/gnocchi.py
@@ -13,8 +13,11 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 #
+import six
+
 from gnocchiclient import auth as gauth
 from gnocchiclient import client as gclient
+from gnocchiclient import exceptions as gexceptions
 from keystoneauth1 import loading as ks_loading
 from oslo_config import cfg
 from oslo_log import log as logging
@@ -309,13 +312,23 @@ class GnocchiCollector(collector.BaseCollector):
         # get groupby
         groupby = self.conf[metric_name]['groupby']
 
-        return self._conn.aggregates.fetch(
-            op,
-            resource_type=resource_type,
-            start=ck_utils.ts2dt(start),
-            stop=ck_utils.ts2dt(end),
-            groupby=groupby,
-            search=self.extend_filter(*query_parameters))
+        try:
+            return self._conn.aggregates.fetch(
+                op,
+                resource_type=resource_type,
+                start=ck_utils.ts2dt(start),
+                stop=ck_utils.ts2dt(end),
+                groupby=groupby,
+                search=self.extend_filter(*query_parameters))
+        except (gexceptions.MetricNotFound, gexceptions.BadRequest) as e:
+            # FIXME(peschk_l): gnocchiclient seems to be raising a BadRequest
+            # when it should be raising MetricNotFound
+            if isinstance(e, gexceptions.BadRequest):
+                if 'Metrics not found' not in six.text_type(e):
+                    raise
+            LOG.warning('[{scope}] Skipping this metric for the '
+                        'current cycle.'.format(scope=project_id, err=e))
+            return []
 
     def _format_data(self, metconf, data, resources_info=None):
         """Formats gnocchi data to CK data.
diff --git a/releasenotes/notes/add-scope-key-58135c2a5c6dae68.yaml b/releasenotes/notes/add-scope-key-58135c2a5c6dae68.yaml
index 0f9185a4..e0a8aa55 100644
--- a/releasenotes/notes/add-scope-key-58135c2a5c6dae68.yaml
+++ b/releasenotes/notes/add-scope-key-58135c2a5c6dae68.yaml
@@ -1,5 +1,5 @@
 ---
 other:
   - |
-    The "scope_key" option is now defained in cloudkitty.conf and has been
+    The "scope_key" option is now defined in cloudkitty.conf and has been
     removed from the cloudkitty and monasca collector's extra_args
diff --git a/releasenotes/notes/skip-period-if-nonexistent-metric-ba56a671e68f5bf5.yaml b/releasenotes/notes/skip-period-if-nonexistent-metric-ba56a671e68f5bf5.yaml
new file mode 100644
index 00000000..a984238d
--- /dev/null
+++ b/releasenotes/notes/skip-period-if-nonexistent-metric-ba56a671e68f5bf5.yaml
@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    The behaviour of the gnocchi collector has changed in case of a nonexistent
+    metric. Given that a nonexistent metric is unlikely to exist in the next
+    collection cycle, the metric is simply skipped.