fix(propagator-aws-xray): correctly propagate over grpc (#2604)

Co-authored-by: Marc Pichler <[email protected]>

Author: dweitzman-codaio

propagators/propagator-aws-xray/src/AWSXRayPropagator.ts

@@ -99,7 +99,10 @@ export class AWSXRayPropagator implements TextMapPropagator {
     if (!relevantHeaderKey) {
       return INVALID_SPAN_CONTEXT;
     }
-    const traceHeader = getter.get(carrier, relevantHeaderKey);
+    const rawTraceHeader = getter.get(carrier, relevantHeaderKey);
+    const traceHeader = Array.isArray(rawTraceHeader)
+      ? rawTraceHeader[0]
+      : rawTraceHeader;
 
     if (!traceHeader || typeof traceHeader !== 'string') {
       return INVALID_SPAN_CONTEXT;

propagators/propagator-aws-xray/test/AWSXRayPropagator.test.ts

@@ -23,6 +23,7 @@ import {
   SpanContext,
   TraceFlags,
   trace,
+  TextMapGetter,
 } from '@opentelemetry/api';
 import { TraceState } from '@opentelemetry/core';
 
@@ -317,6 +318,33 @@ describe('AWSXRayPropagator', () => {
       });
     });
 
+    it('should extract multi header using array getter', () => {
+      carrier[AWSXRAY_TRACE_ID_HEADER] =
+        'Root=1-8a3c60f7-d188f8fa79d48a391a778fa6;Parent=53995c3f42cd8ad8;Sampled=1';
+      const multiGetter: TextMapGetter = {
+        get(carrier, key) {
+          if (carrier == null || carrier[key] === undefined) {
+            return undefined;
+          }
+          return [carrier[key]];
+        },
+        keys: function (carrier: any): string[] {
+          return defaultTextMapGetter.keys(carrier);
+        },
+      };
+
+      const extractedSpanContext = trace
+        .getSpan(xrayPropagator.extract(ROOT_CONTEXT, carrier, multiGetter))
+        ?.spanContext();
+
+      assert.deepStrictEqual(extractedSpanContext, {
+        traceId: TRACE_ID,
+        spanId: SPAN_ID,
+        isRemote: true,
+        traceFlags: TraceFlags.SAMPLED,
+      });
+    });
+
     describe('.fields()', () => {
       it('should return a field with AWS X-Ray Trace ID header', () => {
         const expectedField = xrayPropagator.fields();