opentelemetry-sdk: fix OTLP exporting of histogram explicit buckets advisory

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

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)
+        )