fix(otel): support setting DD_METRICS_OTEL_ENABLED to False (#7028)

Author: mabdinur

packages/dd-trace/src/config.js

@@ -627,8 +627,12 @@ class Config {
     target.otelMaxExportBatchSize = nonNegInt(OTEL_BSP_MAX_EXPORT_BATCH_SIZE, 'OTEL_BSP_MAX_EXPORT_BATCH_SIZE', false)
     target.otelMaxQueueSize = nonNegInt(OTEL_BSP_MAX_QUEUE_SIZE, 'OTEL_BSP_MAX_QUEUE_SIZE', false)
 
-    const otelMetricsExporter = !OTEL_METRICS_EXPORTER || OTEL_METRICS_EXPORTER.toLowerCase() !== 'none'
-    this.#setBoolean(target, 'otelMetricsEnabled', DD_METRICS_OTEL_ENABLED && otelMetricsExporter)
+    const otelMetricsExporterEnabled = OTEL_METRICS_EXPORTER?.toLowerCase() !== 'none'
+    this.#setBoolean(
+      target,
+      'otelMetricsEnabled',
+      DD_METRICS_OTEL_ENABLED && isTrue(DD_METRICS_OTEL_ENABLED) && otelMetricsExporterEnabled
+    )
     // Set OpenTelemetry metrics configuration with specific _METRICS_ vars
     // taking precedence over generic _EXPORTERS_ vars
     if (OTEL_EXPORTER_OTLP_ENDPOINT || OTEL_EXPORTER_OTLP_METRICS_ENDPOINT) {

packages/dd-trace/test/opentelemetry/metrics.spec.js

@@ -834,11 +834,17 @@ describe('OpenTelemetry Meter Provider', () => {
   })
 
   describe('Initialization', () => {
-    it('does not initialize when OTEL metrics are disabled', () => {
+    it('does not initialize when OTEL metrics configuration is unset', () => {
       const { meterProvider } = setupTracer({ DD_METRICS_OTEL_ENABLED: undefined })
       const { MeterProvider } = require('../../src/opentelemetry/metrics')
 
-      // Should return no-op provider when disabled, not our custom MeterProvider
+      assert.strictEqual(meterProvider instanceof MeterProvider, false)
+    })
+
+    it('does not initialize when OTEL metrics are explicitly disabled', () => {
+      const { meterProvider } = setupTracer({ DD_METRICS_OTEL_ENABLED: 'false' })
+      const { MeterProvider } = require('../../src/opentelemetry/metrics')
+
       assert.strictEqual(meterProvider instanceof MeterProvider, false)
     })