From 590392dbd413502ae9ff73fa6737420bca5e624c Mon Sep 17 00:00:00 2001
From: Aksel Allas <aksel.allas@pactum.com>
Date: Wed, 10 Jan 2024 17:15:37 +0200
Subject: [PATCH] feat(add-aggregation-selector-option-to-otlp-metric-exporter)

---
 experimental/CHANGELOG.md                     |  2 ++
 .../src/OTLPMetricExporterBase.ts             | 18 +++++++++++++
 .../src/OTLPMetricExporterOptions.ts          |  6 ++++-
 .../test/node/CollectorMetricExporter.test.ts | 27 +++++++++++++++++++
 4 files changed, 52 insertions(+), 1 deletion(-)

diff --git a/experimental/CHANGELOG.md b/experimental/CHANGELOG.md
index 845a7e7ad6..6733db73d3 100644
--- a/experimental/CHANGELOG.md
+++ b/experimental/CHANGELOG.md
@@ -13,6 +13,8 @@ All notable changes to experimental packages in this project will be documented
 
 ### :rocket: (Enhancement)
 
+* feat(exporter-metrics-otlp-http): add option to set the exporter aggregation preference  [#4409](https://github.com/open-telemetry/opentelemetry-js/pull/4409) @AkselAllas
+
 ### :bug: (Bug Fix)
 
 * fix(instrumentation): use caret range on import-in-the-middle [#4380](https://github.com/open-telemetry/opentelemetry-js/pull/4380) @pichlermarc
diff --git a/experimental/packages/opentelemetry-exporter-metrics-otlp-http/src/OTLPMetricExporterBase.ts b/experimental/packages/opentelemetry-exporter-metrics-otlp-http/src/OTLPMetricExporterBase.ts
index db8a4a32ed..66a5bfb596 100644
--- a/experimental/packages/opentelemetry-exporter-metrics-otlp-http/src/OTLPMetricExporterBase.ts
+++ b/experimental/packages/opentelemetry-exporter-metrics-otlp-http/src/OTLPMetricExporterBase.ts
@@ -21,6 +21,8 @@ import {
   InstrumentType,
   PushMetricExporter,
   ResourceMetrics,
+  Aggregation,
+  AggregationSelector,
 } from '@opentelemetry/sdk-metrics';
 import {
   AggregationTemporalityPreference,
@@ -104,6 +106,16 @@ function chooseTemporalitySelector(
   return chooseTemporalitySelectorFromEnvironment();
 }
 
+function chooseAggregationSelector(
+  config: OTLPMetricExporterOptions | undefined
+) {
+  if (config?.aggregationPreference) {
+    return config.aggregationPreference;
+  } else {
+    return (_instrumentType: any) => Aggregation.Default();
+  }
+}
+
 export class OTLPMetricExporterBase<
   T extends OTLPExporterBase<
     OTLPMetricExporterOptions,
@@ -114,9 +126,11 @@ export class OTLPMetricExporterBase<
 {
   public _otlpExporter: T;
   private _aggregationTemporalitySelector: AggregationTemporalitySelector;
+  private _aggregationSelector: AggregationSelector;
 
   constructor(exporter: T, config?: OTLPMetricExporterOptions) {
     this._otlpExporter = exporter;
+    this._aggregationSelector = chooseAggregationSelector(config);
     this._aggregationTemporalitySelector = chooseTemporalitySelector(
       config?.temporalityPreference
     );
@@ -137,6 +151,10 @@ export class OTLPMetricExporterBase<
     return Promise.resolve();
   }
 
+  selectAggregation(instrumentType: InstrumentType): Aggregation {
+    return this._aggregationSelector(instrumentType);
+  }
+
   selectAggregationTemporality(
     instrumentType: InstrumentType
   ): AggregationTemporality {
diff --git a/experimental/packages/opentelemetry-exporter-metrics-otlp-http/src/OTLPMetricExporterOptions.ts b/experimental/packages/opentelemetry-exporter-metrics-otlp-http/src/OTLPMetricExporterOptions.ts
index e03bde4e75..ff805e3b17 100644
--- a/experimental/packages/opentelemetry-exporter-metrics-otlp-http/src/OTLPMetricExporterOptions.ts
+++ b/experimental/packages/opentelemetry-exporter-metrics-otlp-http/src/OTLPMetricExporterOptions.ts
@@ -15,12 +15,16 @@
  */
 
 import { OTLPExporterConfigBase } from '@opentelemetry/otlp-exporter-base';
-import { AggregationTemporality } from '@opentelemetry/sdk-metrics';
+import {
+  AggregationTemporality,
+  AggregationSelector,
+} from '@opentelemetry/sdk-metrics';
 
 export interface OTLPMetricExporterOptions extends OTLPExporterConfigBase {
   temporalityPreference?:
     | AggregationTemporalityPreference
     | AggregationTemporality;
+  aggregationPreference?: AggregationSelector;
 }
 
 export enum AggregationTemporalityPreference {
diff --git a/experimental/packages/opentelemetry-exporter-metrics-otlp-http/test/node/CollectorMetricExporter.test.ts b/experimental/packages/opentelemetry-exporter-metrics-otlp-http/test/node/CollectorMetricExporter.test.ts
index 66f6af3006..b72ed5f8cb 100644
--- a/experimental/packages/opentelemetry-exporter-metrics-otlp-http/test/node/CollectorMetricExporter.test.ts
+++ b/experimental/packages/opentelemetry-exporter-metrics-otlp-http/test/node/CollectorMetricExporter.test.ts
@@ -43,7 +43,9 @@ import {
 } from '../metricsHelper';
 import { MockedResponse } from './nodeHelpers';
 import {
+  Aggregation,
   AggregationTemporality,
+  ExplicitBucketHistogramAggregation,
   InstrumentType,
   ResourceMetrics,
 } from '@opentelemetry/sdk-metrics';
@@ -218,6 +220,31 @@ describe('OTLPMetricExporter - node with json over http', () => {
     });
   });
 
+  describe('aggregation', () => {
+    it('aggregationSelector calls the selector supplied to the constructor', () => {
+      const aggregation = new ExplicitBucketHistogramAggregation([
+        0, 100, 100000,
+      ]);
+      const exporter = new OTLPMetricExporter({
+        aggregationPreference: _instrumentType => aggregation,
+      });
+      assert.equal(
+        exporter.selectAggregation(InstrumentType.COUNTER),
+        aggregation
+      );
+    });
+
+    it('aggregationSelector returns the default aggregation preference when nothing is supplied', () => {
+      const exporter = new OTLPMetricExporter({
+        aggregationPreference: _instrumentType => Aggregation.Default(),
+      });
+      assert.equal(
+        exporter.selectAggregation(InstrumentType.COUNTER),
+        Aggregation.Default()
+      );
+    });
+  });
+
   describe('when configuring via environment', () => {
     const envSource = process.env;
     it('should use url defined in env that ends with root path and append version and signal path', () => {