opentelemetry-sdk: fix OTLP exporting of histogram explicit buckets advisory (open-telemetry#4434)

OTLP exporters don't rely on the default aggregation for histogram
instead they do it explicitly. So instead of setting boundaries at init
time of ExplicitBucketHistogramAggregation delay it in _create_aggregation
when we have the Histogram at hand.

Co-authored-by: Emídio Neto <[email protected]>

Author: xrmx

CHANGELOG.md

@@ -5,6 +5,11 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## Unreleased
+
+- opentelemetry-sdk: fix OTLP exporting of Histograms with explicit buckets advisory
+  ([#4434](https://github.com/open-telemetry/opentelemetry-python/pull/4434))
+
 ## Version 1.30.0/0.51b0 (2025-02-03)
 
 - Always setup logs sdk, OTEL_PYTHON_LOGGING_AUTO_INSTRUMENTATION_ENABLED only controls python `logging` module handler setup

opentelemetry-sdk/src/opentelemetry/sdk/metrics/_internal/aggregation.py

@@ -1367,10 +1367,6 @@ def __init__(
         boundaries: Optional[Sequence[float]] = None,
         record_min_max: bool = True,
     ) -> None:
-        if boundaries is None:
-            boundaries = (
-                _DEFAULT_EXPLICIT_BUCKET_HISTOGRAM_AGGREGATION_BOUNDARIES
-            )
         self._boundaries = boundaries
         self._record_min_max = record_min_max
 
@@ -1391,6 +1387,12 @@ def _create_aggregation(
                 AggregationTemporality.CUMULATIVE
             )
 
+        if self._boundaries is None:
+            self._boundaries = (
+                instrument._advisory.explicit_bucket_boundaries
+                or _DEFAULT_EXPLICIT_BUCKET_HISTOGRAM_AGGREGATION_BOUNDARIES
+            )
+
         return _ExplicitBucketHistogramAggregation(
             attributes,
             instrument_aggregation_temporality,

opentelemetry-sdk/tests/metrics/integration_test/test_histogram_advisory_explicit_buckets.py

@@ -15,6 +15,7 @@
 from unittest import TestCase
 
 from opentelemetry.sdk.metrics import MeterProvider
+from opentelemetry.sdk.metrics._internal.instrument import Histogram
 from opentelemetry.sdk.metrics.export import InMemoryMetricReader
 from opentelemetry.sdk.metrics.view import (
     ExplicitBucketHistogramAggregation,
@@ -133,3 +134,33 @@ def test_view_overrides_buckets(self):
         self.assertEqual(
             metric.data.data_points[0].explicit_bounds, (10.0, 100.0, 1000.0)
         )
+
+    def test_explicit_aggregation(self):
+        reader = InMemoryMetricReader(
+            preferred_aggregation={
+                Histogram: ExplicitBucketHistogramAggregation()
+            }
+        )
+        meter_provider = MeterProvider(
+            metric_readers=[reader],
+        )
+        meter = meter_provider.get_meter("testmeter")
+        histogram = meter.create_histogram(
+            "testhistogram",
+            explicit_bucket_boundaries_advisory=[1.0, 2.0, 3.0],
+        )
+        histogram.record(1, {"label": "value"})
+        histogram.record(2, {"label": "value"})
+        histogram.record(3, {"label": "value"})
+
+        metrics = reader.get_metrics_data()
+        self.assertEqual(len(metrics.resource_metrics), 1)
+        self.assertEqual(len(metrics.resource_metrics[0].scope_metrics), 1)
+        self.assertEqual(
+            len(metrics.resource_metrics[0].scope_metrics[0].metrics), 1
+        )
+        metric = metrics.resource_metrics[0].scope_metrics[0].metrics[0]
+        self.assertEqual(metric.name, "testhistogram")
+        self.assertEqual(
+            metric.data.data_points[0].explicit_bounds, (1.0, 2.0, 3.0)
+        )