Sort by label keys before generating labels key and value lists

CHANGELOG.md

@@ -19,6 +19,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   ([#3785](https://github.com/open-telemetry/opentelemetry-python/pull/3785))
 - Add capture the fully qualified type name for raised exceptions in spans
   ([#3837](https://github.com/open-telemetry/opentelemetry-python/pull/3837))
+- Prometheus exporter sort label keys to prevent duplicate metrics when user input changes order 
+  ([#3698](https://github.com/open-telemetry/opentelemetry-python/pull/3698))
 
 ## Version 1.24.0/0.45b0 (2024-03-28)
 

exporter/opentelemetry-exporter-prometheus/src/opentelemetry/exporter/prometheus/__init__.py

@@ -237,7 +237,7 @@ def _translate_to_prometheus(
                 label_keys = []
                 label_values = []
 
-                for key, value in number_data_point.attributes.items():
+                for key, value in sorted(number_data_point.attributes.items()):
                     label_keys.append(self._sanitize(key))
                     label_values.append(self._check_value(value))
 

exporter/opentelemetry-exporter-prometheus/tests/test_prometheus_exporter.py

@@ -436,3 +436,24 @@ def test_target_info_sanitize(self):
             prometheus_metric.samples[0].labels["ratio"],
             "0.1",
         )
+
+    def test_label_order_does_not_matter(self):
+        metric_reader = PrometheusMetricReader()
+        provider = MeterProvider(metric_readers=[metric_reader])
+        meter = provider.get_meter("getting-started", "0.1.2")
+        counter = meter.create_counter("counter")
+
+        counter.add(1, {'cause': 'cause1', 'reason': 'reason1'})
+        counter.add(1, {'reason': 'reason2', 'cause': 'cause2'})
+
+        prometheus_output = generate_latest().decode()
+
+        # All labels are mapped correctly
+        self.assertIn('cause="cause1"', prometheus_output)
+        self.assertIn('cause="cause2"', prometheus_output)
+        self.assertIn('reason="reason1"', prometheus_output)
+        self.assertIn('reason="reason2"', prometheus_output)
+
+        # Only one metric is generated
+        metric_count = prometheus_output.count('# HELP counter_total')
+        self.assertEqual(metric_count, 1)