fix: omit SAMPLED header if sampling decision is absent

open-telemetry · Aug 29, 2019 · 0c381ae · 0c381ae
1 parent d4abab6
commit 0c381ae
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Showing 2 changed files with 5 additions and 7 deletions.
diff --git a/packages/opentelemetry-core/src/context/propagation/B3Format.ts b/packages/opentelemetry-core/src/context/propagation/B3Format.ts
@@ -52,12 +52,10 @@ export class B3Format implements HttpTextFormat {
       carrier[X_B3_TRACE_ID] = spanContext.traceId;
       carrier[X_B3_SPAN_ID] = spanContext.spanId;
 
-      if (spanContext.traceOptions === undefined) {
-        carrier[X_B3_SAMPLED] = TraceOptions.SAMPLED;
-      } else {
-        carrier[X_B3_SAMPLED] = Number(
-          spanContext.traceOptions || TraceOptions.UNSAMPLED
-        );
+      // We set the header only if there is an existing sampling decision.
+      // Otherwise we will omit it => Absent.
+      if (spanContext.traceOptions !== undefined) {
+        carrier[X_B3_SAMPLED] = Number(spanContext.traceOptions);
       }
     }
   }

diff --git a/packages/opentelemetry-core/test/context/B3Format.test.ts b/packages/opentelemetry-core/test/context/B3Format.test.ts
@@ -88,7 +88,7 @@ describe('B3Format', () => {
         'd4cda95b652f4a1592b449d5929fda1b'
       );
       assert.deepStrictEqual(carrier[X_B3_SPAN_ID], '6e0c63257de34c92');
-      assert.deepStrictEqual(carrier[X_B3_SAMPLED], TraceOptions.SAMPLED);
+      assert.deepStrictEqual(carrier[X_B3_SAMPLED], undefined);
     });
   });