Move feature to exporter

exporter/opentelemetry-exporter-otlp-proto-http/src/opentelemetry/exporter/otlp/proto/http/metric_exporter/__init__.py

@@ -18,10 +18,18 @@
 from typing import Dict, Optional, Any, Callable, List
 from typing import Sequence, Mapping  # noqa: F401
 
+from opentelemetry.sdk.environment_variables import (
+    OTEL_EXPORTER_OTLP_METRICS_DEFAULT_HISTOGRAM_AGGREGATION,
+)
 from io import BytesIO
 from time import sleep
 from deprecated import deprecated
 
+from opentelemetry.sdk.metrics._internal.aggregation import (
+    _ExponentialBucketHistogramAggregation,
+    _ExplicitBucketHistogramAggregation,
+)
+
 from opentelemetry.exporter.otlp.proto.common._internal import (
     _get_resource_data,
 )
@@ -205,10 +213,38 @@ def __init__(
 
         instrument_class_temporality.update(preferred_temporality or {})
 
+        otel_exporter_otlp_metrics_default_histogram_aggregation = environ.get(
+            OTEL_EXPORTER_OTLP_METRICS_DEFAULT_HISTOGRAM_AGGREGATION,
+            "explicit_bucket_histogram",
+        )
+
+        if otel_exporter_otlp_metrics_default_histogram_aggregation == (
+            "base2_exponential_bucket_histogram"
+        ):
+
+            histogram_aggregation_type = _ExponentialBucketHistogramAggregation
+
+        else:
+
+            if otel_exporter_otlp_metrics_default_histogram_aggregation != (
+                "explicit_bucket_histogram"
+            ):
+
+                _logger.warning(
+                    (
+                        "Invalid value for %s: %s, using explicit bucket "
+                        "histogram aggregation"
+                    ),
+                    OTEL_EXPORTER_OTLP_METRICS_DEFAULT_HISTOGRAM_AGGREGATION,
+                    histogram_aggregation_type,
+                )
+
+            histogram_aggregation_type = _ExplicitBucketHistogramAggregation
+
         MetricExporter.__init__(
             self,
             preferred_temporality=instrument_class_temporality,
-            preferred_aggregation=preferred_aggregation,
+            preferred_aggregation={Histogram, histogram_aggregation_type},
         )
 
     def _export(self, serialized_data: str):

exporter/opentelemetry-exporter-otlp-proto-http/tests/metrics/test_otlp_metrics_exporter.py

@@ -15,7 +15,7 @@
 from logging import WARNING
 from os import environ
 from unittest import TestCase
-from unittest.mock import patch
+from unittest.mock import Mock, patch
 
 from requests import Session
 from requests.models import Response
@@ -40,6 +40,7 @@
     OTEL_EXPORTER_OTLP_HEADERS,
     OTEL_EXPORTER_OTLP_METRICS_CERTIFICATE,
     OTEL_EXPORTER_OTLP_METRICS_COMPRESSION,
+    OTEL_EXPORTER_OTLP_METRICS_DEFAULT_HISTOGRAM_AGGREGATION,
     OTEL_EXPORTER_OTLP_METRICS_ENDPOINT,
     OTEL_EXPORTER_OTLP_METRICS_HEADERS,
     OTEL_EXPORTER_OTLP_METRICS_TEMPORALITY_PREFERENCE,
@@ -54,13 +55,18 @@
     ObservableUpDownCounter,
     UpDownCounter,
 )
+from opentelemetry.sdk.metrics._internal.aggregation import (
+    _ExplicitBucketHistogramAggregation,
+    _ExponentialBucketHistogramAggregation,
+)
 from opentelemetry.sdk.metrics.export import (
     AggregationTemporality,
     MetricExportResult,
     MetricsData,
     ResourceMetrics,
     ScopeMetrics,
 )
+from opentelemetry.sdk.metrics.view import DefaultAggregation
 from opentelemetry.sdk.resources import Resource
 from opentelemetry.sdk.util.instrumentation import (
     InstrumentationScope as SDKInstrumentationScope,
@@ -424,3 +430,60 @@ def test_aggregation_temporality(self):
                 otlp_metric_exporter._preferred_temporality[ObservableGauge],
                 AggregationTemporality.CUMULATIVE,
             )
+
+    def test_exponential_explicit_bucket_histogram(self):
+
+        histogram = Mock(spec=Histogram)
+        default_aggregation = DefaultAggregation()
+
+        self.assertIsInstance(
+            default_aggregation._create_aggregation(histogram, Mock(), Mock()),
+            _ExplicitBucketHistogramAggregation,
+        )
+
+        with patch.dict(
+            environ,
+            {
+                OTEL_EXPORTER_OTLP_METRICS_DEFAULT_HISTOGRAM_AGGREGATION: "base2_exponential_bucket_histogram"
+            },
+        ):
+            self.assertIsInstance(
+                default_aggregation._create_aggregation(
+                    histogram, Mock(), Mock()
+                ),
+                _ExponentialBucketHistogramAggregation,
+            )
+
+        with patch.dict(
+            environ,
+            {OTEL_EXPORTER_OTLP_METRICS_DEFAULT_HISTOGRAM_AGGREGATION: "abc"},
+        ):
+            with self.assertLogs(level=WARNING) as log:
+                self.assertIsInstance(
+                    default_aggregation._create_aggregation(
+                        histogram, Mock(), Mock()
+                    ),
+                    _ExplicitBucketHistogramAggregation,
+                )
+            self.assertEqual(
+                log.output[0],
+                (
+                    "WARNING:opentelemetry.sdk.metrics._internal.aggregation:"
+                    "Invalid value for OTEL_EXPORTER_OTLP_METRICS_DEFAULT_"
+                    "HISTOGRAM_AGGREGATION: abc, using explicit bucket "
+                    "histogram aggregation"
+                ),
+            )
+
+        with patch.dict(
+            environ,
+            {
+                OTEL_EXPORTER_OTLP_METRICS_DEFAULT_HISTOGRAM_AGGREGATION: "explicit_bucket_histogram"
+            },
+        ):
+            self.assertIsInstance(
+                default_aggregation._create_aggregation(
+                    histogram, Mock(), Mock()
+                ),
+                _ExplicitBucketHistogramAggregation,
+            )

opentelemetry-sdk/src/opentelemetry/sdk/environment_variables.py

@@ -650,7 +650,7 @@
 The :envvar:`OTEL_METRICS_EXEMPLAR_FILTER` is the filter for which measurements can become Exemplars.
 """
 
-_OTEL_EXPORTER_OTLP_METRICS_DEFAULT_HISTOGRAM_AGGREGATION = (
+OTEL_EXPORTER_OTLP_METRICS_DEFAULT_HISTOGRAM_AGGREGATION = (
     "OTEL_EXPORTER_OTLP_METRICS_DEFAULT_HISTOGRAM_AGGREGATION"
 )
 """