Use specific exception for duplicate timeseries

Use sub-class of ValueError instead of ValueError, so that we can
distinguish issues caused by wrong input (like invalid name format)
from duplicate metrics being registered into the same registry.

Signed-off-by: Takashi Kajinami <kajinamit@oss.nttdata.com>

Author: kajinamit

prometheus_client/core.py

@@ -4,14 +4,15 @@
     HistogramMetricFamily, InfoMetricFamily, Metric, StateSetMetricFamily,
     SummaryMetricFamily, UnknownMetricFamily, UntypedMetricFamily,
 )
-from .registry import CollectorRegistry, REGISTRY
+from .registry import CollectorRegistry, DuplicateTimeseries, REGISTRY
 from .samples import BucketSpan, Exemplar, NativeHistogram, Sample, Timestamp
 
 __all__ = (
     'BucketSpan',
     'CollectorRegistry',
     'Counter',
     'CounterMetricFamily',
+    'DuplicateTimeseries',
     'Enum',
     'Exemplar',
     'Gauge',

prometheus_client/registry.py

@@ -1,6 +1,6 @@
 import copy
 from threading import Lock
-from typing import Dict, Iterable, List, Optional, Protocol
+from typing import Dict, Iterable, List, Optional, Protocol, Set
 
 from .metrics_core import Metric
 
@@ -15,6 +15,14 @@ def collect(self) -> Iterable[Metric]:
         return []
 
 
+class DuplicateTimeseries(ValueError):
+    def __init__(self, duplicates: Set[str]):
+        msg = 'Duplicated timeseries in CollectorRegistry: {}'.format(
+            duplicates)
+        super().__init__(msg)
+        self.duplicates: Set[str] = duplicates
+
+
 class CollectorRegistry:
     """Metric collector registry.
 
@@ -40,9 +48,7 @@ def register(self, collector: Collector) -> None:
             names = self._get_names(collector)
             duplicates = set(self._names_to_collectors).intersection(names)
             if duplicates:
-                raise ValueError(
-                    'Duplicated timeseries in CollectorRegistry: {}'.format(
-                        duplicates))
+                raise DuplicateTimeseries(duplicates)
             for name in names:
                 self._names_to_collectors[name] = collector
             self._collector_to_names[collector] = names

tests/test_core.py

@@ -7,8 +7,8 @@
 
 from prometheus_client import metrics
 from prometheus_client.core import (
-    CollectorRegistry, Counter, CounterMetricFamily, Enum, Gauge,
-    GaugeHistogramMetricFamily, GaugeMetricFamily, Histogram,
+    CollectorRegistry, Counter, CounterMetricFamily, DuplicateTimeseries,
+    Enum, Gauge, GaugeHistogramMetricFamily, GaugeMetricFamily, Histogram,
     HistogramMetricFamily, Info, InfoMetricFamily, Metric, Sample,
     StateSetMetricFamily, Summary, SummaryMetricFamily, UntypedMetricFamily,
 )
@@ -916,41 +916,41 @@ class TestCollectorRegistry(unittest.TestCase):
     def test_duplicate_metrics_raises(self):
         registry = CollectorRegistry()
         Counter('c_total', 'help', registry=registry)
-        self.assertRaises(ValueError, Counter, 'c_total', 'help', registry=registry)
-        self.assertRaises(ValueError, Gauge, 'c_total', 'help', registry=registry)
-        self.assertRaises(ValueError, Gauge, 'c_created', 'help', registry=registry)
+        self.assertRaises(DuplicateTimeseries, Counter, 'c_total', 'help', registry=registry)
+        self.assertRaises(DuplicateTimeseries, Gauge, 'c_total', 'help', registry=registry)
+        self.assertRaises(DuplicateTimeseries, Gauge, 'c_created', 'help', registry=registry)
 
         Gauge('g_created', 'help', registry=registry)
-        self.assertRaises(ValueError, Gauge, 'g_created', 'help', registry=registry)
-        self.assertRaises(ValueError, Counter, 'g', 'help', registry=registry)
+        self.assertRaises(DuplicateTimeseries, Gauge, 'g_created', 'help', registry=registry)
+        self.assertRaises(DuplicateTimeseries, Counter, 'g', 'help', registry=registry)
 
         Summary('s', 'help', registry=registry)
-        self.assertRaises(ValueError, Summary, 's', 'help', registry=registry)
-        self.assertRaises(ValueError, Gauge, 's_created', 'help', registry=registry)
-        self.assertRaises(ValueError, Gauge, 's_sum', 'help', registry=registry)
-        self.assertRaises(ValueError, Gauge, 's_count', 'help', registry=registry)
+        self.assertRaises(DuplicateTimeseries, Summary, 's', 'help', registry=registry)
+        self.assertRaises(DuplicateTimeseries, Gauge, 's_created', 'help', registry=registry)
+        self.assertRaises(DuplicateTimeseries, Gauge, 's_sum', 'help', registry=registry)
+        self.assertRaises(DuplicateTimeseries, Gauge, 's_count', 'help', registry=registry)
         # We don't currently expose quantiles, but let's prevent future
         # clashes anyway.
-        self.assertRaises(ValueError, Gauge, 's', 'help', registry=registry)
+        self.assertRaises(DuplicateTimeseries, Gauge, 's', 'help', registry=registry)
 
         Histogram('h', 'help', registry=registry)
-        self.assertRaises(ValueError, Histogram, 'h', 'help', registry=registry)
+        self.assertRaises(DuplicateTimeseries, Histogram, 'h', 'help', registry=registry)
         # Clashes aggaint various suffixes.
-        self.assertRaises(ValueError, Summary, 'h', 'help', registry=registry)
-        self.assertRaises(ValueError, Gauge, 'h_count', 'help', registry=registry)
-        self.assertRaises(ValueError, Gauge, 'h_sum', 'help', registry=registry)
-        self.assertRaises(ValueError, Gauge, 'h_bucket', 'help', registry=registry)
-        self.assertRaises(ValueError, Gauge, 'h_created', 'help', registry=registry)
+        self.assertRaises(DuplicateTimeseries, Summary, 'h', 'help', registry=registry)
+        self.assertRaises(DuplicateTimeseries, Gauge, 'h_count', 'help', registry=registry)
+        self.assertRaises(DuplicateTimeseries, Gauge, 'h_sum', 'help', registry=registry)
+        self.assertRaises(DuplicateTimeseries, Gauge, 'h_bucket', 'help', registry=registry)
+        self.assertRaises(DuplicateTimeseries, Gauge, 'h_created', 'help', registry=registry)
         # The name of the histogram itself is also taken.
-        self.assertRaises(ValueError, Gauge, 'h', 'help', registry=registry)
+        self.assertRaises(DuplicateTimeseries, Gauge, 'h', 'help', registry=registry)
 
         Info('i', 'help', registry=registry)
-        self.assertRaises(ValueError, Gauge, 'i_info', 'help', registry=registry)
+        self.assertRaises(DuplicateTimeseries, Gauge, 'i_info', 'help', registry=registry)
 
     def test_unregister_works(self):
         registry = CollectorRegistry()
         s = Summary('s', 'help', registry=registry)
-        self.assertRaises(ValueError, Gauge, 's_count', 'help', registry=registry)
+        self.assertRaises(DuplicateTimeseries, Gauge, 's_count', 'help', registry=registry)
         registry.unregister(s)
         Gauge('s_count', 'help', registry=registry)