feat(auto-instrumentations-node): add getPropagator to get propagators from environment

metapackages/auto-instrumentations-node/package.json

@@ -94,7 +94,12 @@
     "@opentelemetry/resource-detector-container": "^0.3.9",
     "@opentelemetry/resource-detector-gcp": "^0.29.9",
     "@opentelemetry/resources": "^1.24.0",
-    "@opentelemetry/sdk-node": "^0.51.0"
+    "@opentelemetry/sdk-node": "^0.51.0",
+    "@opentelemetry/core": "^1.24.1",
+    "@opentelemetry/propagator-b3": "^1.24.1",
+    "@opentelemetry/propagator-jaeger": "^1.24.1",
+    "@opentelemetry/propagator-aws-xray": "^1.24.1",
+    "@opentelemetry/propagator-ot-trace": "^0.27.2"
   },
   "files": [
     "build/src/**/*.js",

metapackages/auto-instrumentations-node/src/index.ts

@@ -17,5 +17,6 @@
 export {
   getNodeAutoInstrumentations,
   getResourceDetectorsFromEnv as getResourceDetectors,
+  getPropagator,
   InstrumentationConfigMap,
 } from './utils';

metapackages/auto-instrumentations-node/src/register.ts

@@ -17,6 +17,7 @@ import * as opentelemetry from '@opentelemetry/sdk-node';
 import { diag, DiagConsoleLogger } from '@opentelemetry/api';
 import {
   getNodeAutoInstrumentations,
+  getPropagator,
   getResourceDetectorsFromEnv,
 } from './utils';
 
@@ -28,6 +29,7 @@ diag.setLogger(
 const sdk = new opentelemetry.NodeSDK({
   instrumentations: getNodeAutoInstrumentations(),
   resourceDetectors: getResourceDetectorsFromEnv(),
+  textMapPropagator: getPropagator(),
 });
 
 try {

metapackages/auto-instrumentations-node/src/utils.ts

@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-import { diag } from '@opentelemetry/api';
+import { diag, TextMapPropagator } from '@opentelemetry/api';
 import { Instrumentation } from '@opentelemetry/instrumentation';
 
 import { AmqplibInstrumentation } from '@opentelemetry/instrumentation-amqplib';
@@ -80,6 +80,15 @@
   azureFunctionsDetector,
   azureVmDetector,
 } from '@opentelemetry/resource-detector-azure';
+import {
+  CompositePropagator,
+  W3CBaggagePropagator,
+  W3CTraceContextPropagator,
+} from '@opentelemetry/core';
+import { B3InjectEncoding, B3Propagator } from '@opentelemetry/propagator-b3';
+import { JaegerPropagator } from '@opentelemetry/propagator-jaeger';
+import { OTTracePropagator } from '@opentelemetry/propagator-ot-trace';
+import { AWSXRayPropagator } from '@opentelemetry/propagator-aws-xray';
 
 const RESOURCE_DETECTOR_CONTAINER = 'container';
 const RESOURCE_DETECTOR_ENVIRONMENT = 'env';
@@ -253,3 +262,56 @@
     return resourceDetector || [];
   });
 }
+
+type PropagatorFactoryFunction = () => TextMapPropagator;
+
+const propagatorMap = new Map<string, PropagatorFactoryFunction>([
+  ['tracecontext', () => new W3CTraceContextPropagator()],
+  ['baggage', () => new W3CTraceContextPropagator()],
+  [
+    'b3',
+    () => new B3Propagator({ injectEncoding: B3InjectEncoding.SINGLE_HEADER }),
+  ],
+  [
+    'b3multi',
+    () => new B3Propagator({ injectEncoding: B3InjectEncoding.MULTI_HEADER }),
+  ],
+  ['jaeger', () => new JaegerPropagator()],
+  ['xray', () => new AWSXRayPropagator()],
+  ['ottrace', () => new OTTracePropagator()],
+]);
+
+/**
+ * Get a propagator based on the OTEL_PROPAGATORS env var.
+ */
+export function getPropagator(): TextMapPropagator {
+  if (process.env.OTEL_PROPAGATORS == null) {
+    return new CompositePropagator({
+      propagators: [
+        new W3CTraceContextPropagator(),
+        new W3CBaggagePropagator(),
+      ],
+    });
+  }
+
+  const propagatorsFromEnv = process.env.OTEL_PROPAGATORS?.split(',').map(
+    value => value.toLowerCase()
+  );
+
+  const propagators = propagatorsFromEnv.flatMap(propagatorName => {
+    const propagatorFactoryFunction = propagatorMap.get(propagatorName);
+    if (propagatorFactoryFunction == null) {
+      diag.error(
+        `Invalid propagator "${propagatorName}" specified in the environment variable OTEL_PROPAGATORS`
+      );
+      return [];
+    }
+    return propagatorFactoryFunction();
+  });
+
+  if (propagators.length === 1) {
+    return propagators[0];
+  }
+
+  return new CompositePropagator({ propagators });
+}

metapackages/auto-instrumentations-node/test/utils.test.ts

@@ -19,7 +19,7 @@ import { HttpInstrumentationConfig } from '@opentelemetry/instrumentation-http';
 import * as assert from 'assert';
 import * as sinon from 'sinon';
 import { getNodeAutoInstrumentations } from '../src';
-import { getResourceDetectorsFromEnv } from '../src/utils';
+import { getPropagator, getResourceDetectorsFromEnv } from '../src/utils';
 
 describe('utils', () => {
   describe('getNodeAutoInstrumentations', () => {
@@ -161,4 +161,31 @@ describe('utils', () => {
       delete process.env.OTEL_NODE_RESOURCE_DETECTORS;
     });
   });
+
+  describe('getPropagator', () => {
+    afterEach(() => {
+      delete process.env.OTEL_PROPAGATORS;
+    });
+
+    it('should return default when env var is unset', () => {
+      assert.deepStrictEqual(getPropagator().fields(), [
+        'traceparent',
+        'tracestate',
+        'baggage',
+      ]);
+    });
+
+    it('should return the selected propagator when one is in the list', () => {
+      process.env.OTEL_PROPAGATORS = 'tracecontext';
+      assert.deepStrictEqual(getPropagator().fields(), [
+        'traceparent',
+        'tracestate',
+      ]);
+    });
+
+    it('should return the selected propagators when multiple are in the list', () => {
+      process.env.OTEL_PROPAGATORS = 'b3,jaeger';
+      assert.deepStrictEqual(getPropagator().fields(), ['b3', 'uber-trace-id']);
+    });
+  });
 });