Check for duplicates in "groupby" and "metadata" for each metric

This updates the "cloudkitty.collector.validate_conf" function in order to
check for duplicates between "groupby" and "metadata" in the metrics.yml
configuration file.

Change-Id: Ic1d3e301d111a5694aff3a665aff261c562a0efc
Story: 2006941
Task: 37615

cloudkitty/collector/__init__.py

@@ -248,6 +248,29 @@ class BaseCollector(object):
         return name, data
 
 
+class InvalidConfiguration(Exception):
+    pass
+
+
+def check_duplicates(metric_name, metric):
+    """Checks for duplicates in "groupby" and "metadata".
+
+    :param metric: config dict for a metric to check
+    :type metric: dict
+    """
+    groupby = set(metric['groupby'])
+    metadata = set(metric['metadata'])
+    duplicates = groupby.intersection(metadata)
+    if duplicates:
+        raise InvalidConfiguration(
+            'Metric {} has duplicates in groupby and metadata: {}'.format(
+                metric_name, metric))
+
+    metric['groupby'] = list(groupby)
+    metric['metadata'] = list(metadata)
+    return metric
+
+
 def validate_conf(conf):
     """Validates the provided configuration."""
     collector = get_collector_without_invoke()
@@ -255,4 +278,5 @@ def validate_conf(conf):
     for metric_name, metric in output.items():
         if 'alt_name' not in metric.keys():
             metric['alt_name'] = metric_name
+        check_duplicates(metric_name, metric)
     return output

cloudkitty/tests/collectors/test_validation.py

@@ -27,7 +27,7 @@ class MetricConfigValidationTest(tests.TestCase):
         'metrics': {
             'metric_one': {
                 'groupby': ['one'],
-                'metadata': ['one'],
+                'metadata': ['two'],
                 'unit': 'u',
             }
         }
@@ -36,7 +36,7 @@ class MetricConfigValidationTest(tests.TestCase):
     base_output = {
         'metric_one': {
             'groupby': ['one'],
-            'metadata': ['one'],
+            'metadata': ['two'],
             'unit': 'u',
             'factor': 1,
             'offset': 0,
@@ -166,3 +166,11 @@ class MetricConfigValidationTest(tests.TestCase):
             collector.prometheus.PrometheusCollector.check_configuration(data),
             expected_output,
         )
+
+    def test_check_duplicates(self):
+        data = copy.deepcopy(self.base_data)
+        for metric_name, metric in data['metrics'].items():
+            metric['metadata'].append('one')
+            self.assertRaises(
+                collector.InvalidConfiguration,
+                collector.check_duplicates, metric_name, metric)

releasenotes/notes/check-duplicates-metadata-groupby-d5ee99941bb483fd.yaml

@@ -0,0 +1,5 @@
+---
+upgrade:
+  - |
+    When the config is loaded, there is now a verification for duplicates
+    between ``groupby`` and ``metadata`` for each metric.