Set OTLP Metric Temporality to Delta

src/agent/aksLoader.ts

@@ -11,7 +11,7 @@ import { InstrumentationOptions } from '../types';
 import { OTLPMetricExporter as OTLPProtoMetricExporter } from "@opentelemetry/exporter-metrics-otlp-proto";
 import { OTLPMetricExporter as OTLPHttpMetricExporter } from "@opentelemetry/exporter-metrics-otlp-http";
 import { MetricReader, PeriodicExportingMetricReader } from "@opentelemetry/sdk-metrics";
-import { OTLP_METRIC_EXPORTER_EXPORT_INTERVAL } from './types';
+import { ENV_OTEL_EXPORTER_OTLP_METRICS_TEMPORALITY_PREFERENCE, OTLP_METRIC_EXPORTER_EXPORT_INTERVAL } from './types';
 
 export class AKSLoader extends AgentLoader {
 
@@ -55,6 +55,9 @@ export class AKSLoader extends AgentLoader {
                 )
             );
 
+            // Ensure Delta temporality is used for OTLP metrics
+            process.env[ENV_OTEL_EXPORTER_OTLP_METRICS_TEMPORALITY_PREFERENCE] = "Delta";
+
             // Create metricReaders array and add OTLP reader if environment variables request it
             try {
                 const metricReaders: MetricReader[] = [];

src/agent/types.ts

@@ -5,6 +5,7 @@ export const AZURE_APP_NAME = process.env.WEBSITE_SITE_NAME || 'unknown';
 export const AZURE_MONITOR_AUTO_ATTACH = "AZURE_MONITOR_AUTO_ATTACH";
 
 export const OTLP_METRIC_EXPORTER_EXPORT_INTERVAL = 60000; // in ms
+export const ENV_OTEL_EXPORTER_OTLP_METRICS_TEMPORALITY_PREFERENCE = "OTEL_EXPORTER_OTLP_METRICS_TEMPORALITY_PREFERENCE";
 
 export interface IAgentLogger {
     log(message: any, ...optional: any[]): void;

test/unitTests/agent/aksLoader.tests.ts

@@ -355,6 +355,21 @@ describe("agent/AKSLoader", () => {
         assert.equal(exporter.constructor.name, "OTLPMetricExporter", "Should be an OTLPMetricExporter");
     });
 
+    it("constructor sets OTEL_EXPORTER_OTLP_METRICS_TEMPORALITY_PREFERENCE to Delta", () => {
+        const env = {
+            ["APPLICATIONINSIGHTS_CONNECTION_STRING"]: "InstrumentationKey=1aa11111-bbbb-1ccc-8ddd-eeeeffff3333",
+        };
+        process.env = env;
+
+        new AKSLoader();
+
+        assert.equal(
+            process.env["OTEL_EXPORTER_OTLP_METRICS_TEMPORALITY_PREFERENCE"],
+            "Delta",
+            "OTEL_EXPORTER_OTLP_METRICS_TEMPORALITY_PREFERENCE should be set to Delta"
+        );
+    });
+
     it("constructor creates OTLP metric reader when OTEL_METRICS_EXPORTER contains mixed case otlp with other exporters", () => {
         const env = {
             ["APPLICATIONINSIGHTS_CONNECTION_STRING"]: "InstrumentationKey=1aa11111-bbbb-1ccc-8ddd-eeeeffff3333",