feat: add IsRemote field to SpanContext, set by propagators (#451)

* feat(opentelemetry-types): add isRemote field

* fix(opentelemetry-core): set isRemote true when extracting

* fix(opentelemetry-core): set isRemote on BinaryTraceContext

* fix(opentelemetry-types): adjust isRemote comment

Makes it more obvious when the flag changes and what the default value is.

Author: KaindlJulian

packages/opentelemetry-core/src/context/propagation/B3Format.ts

@@ -76,6 +76,7 @@ export class B3Format implements HttpTextFormat {
       return {
         traceId,
         spanId,
+        isRemote: true,
         traceFlags: isNaN(Number(options))
           ? TraceFlags.UNSAMPLED
           : Number(options),

packages/opentelemetry-core/src/context/propagation/BinaryTraceContext.ts

@@ -86,6 +86,9 @@ export class BinaryTraceContext implements BinaryFormat {
     ) {
       return null;
     }
+
+    result.isRemote = true;
+
     // See serializeSpanContext for byte offsets.
     result.traceId = toHex(buf.slice(TRACE_ID_OFFSET, SPAN_ID_FIELD_ID_OFFSET));
     result.spanId = toHex(

packages/opentelemetry-core/src/context/propagation/HttpTraceContext.ts

@@ -90,6 +90,8 @@ export class HttpTraceContext implements HttpTextFormat {
     const spanContext = parse(traceParent);
     if (!spanContext) return null;
 
+    spanContext.isRemote = true;
+
     const traceStateHeader = carrier[TRACE_STATE_HEADER];
     if (traceStateHeader) {
       // If more than one `tracestate` header is found, we merge them into a

packages/opentelemetry-core/test/context/B3Format.test.ts

@@ -55,6 +55,7 @@ describe('B3Format', () => {
         spanId: '6e0c63257de34c92',
         traceFlags: TraceFlags.UNSAMPLED,
         traceState: new TraceState('foo=bar,baz=qux'),
+        isRemote: false,
       };
 
       b3Format.inject(spanContext, 'B3Format', carrier);
@@ -101,6 +102,7 @@ describe('B3Format', () => {
       assert.deepStrictEqual(extractedSpanContext, {
         spanId: 'b7ad6b7169203331',
         traceId: '0af7651916cd43dd8448eb211c80319c',
+        isRemote: true,
         traceFlags: TraceFlags.UNSAMPLED,
       });
     });
@@ -114,6 +116,7 @@ describe('B3Format', () => {
       assert.deepStrictEqual(extractedSpanContext, {
         spanId: 'b7ad6b7169203331',
         traceId: '0af7651916cd43dd8448eb211c80319c',
+        isRemote: true,
         traceFlags: TraceFlags.SAMPLED,
       });
     });
@@ -127,6 +130,7 @@ describe('B3Format', () => {
       assert.deepStrictEqual(extractedSpanContext, {
         spanId: 'b7ad6b7169203331',
         traceId: '0af7651916cd43dd8448eb211c80319c',
+        isRemote: true,
         traceFlags: TraceFlags.SAMPLED,
       });
     });
@@ -140,6 +144,7 @@ describe('B3Format', () => {
       assert.deepStrictEqual(extractedSpanContext, {
         spanId: 'b7ad6b7169203331',
         traceId: '0af7651916cd43dd8448eb211c80319c',
+        isRemote: true,
         traceFlags: TraceFlags.UNSAMPLED,
       });
     });
@@ -173,6 +178,7 @@ describe('B3Format', () => {
       assert.deepStrictEqual(extractedSpanContext, {
         spanId: 'b7ad6b7169203331',
         traceId: '0af7651916cd43dd8448eb211c80319c',
+        isRemote: true,
         traceFlags: TraceFlags.SAMPLED,
       });
     });

packages/opentelemetry-core/test/context/BinaryTraceContext.test.ts

@@ -134,7 +134,7 @@ describe('BinaryTraceContext', () => {
           binaryTraceContext.fromBytes(testCase.binary),
           testCase.structured &&
             Object.assign(
-              { traceFlags: TraceFlags.UNSAMPLED },
+              { isRemote: true, traceFlags: TraceFlags.UNSAMPLED },
               testCase.structured
             )
         );

packages/opentelemetry-core/test/context/HttpTraceContext.test.ts

@@ -76,6 +76,7 @@ describe('HttpTraceContext', () => {
       assert.deepStrictEqual(extractedSpanContext, {
         spanId: 'b7ad6b7169203331',
         traceId: '0af7651916cd43dd8448eb211c80319c',
+        isRemote: true,
         traceFlags: TraceFlags.SAMPLED,
       });
     });
@@ -106,6 +107,7 @@ describe('HttpTraceContext', () => {
       assert.deepStrictEqual(extractedSpanContext, {
         spanId: 'b7ad6b7169203331',
         traceId: '0af7651916cd43dd8448eb211c80319c',
+        isRemote: true,
         traceFlags: TraceFlags.SAMPLED,
       });
     });
@@ -139,6 +141,7 @@ describe('HttpTraceContext', () => {
       assert.deepStrictEqual(extractedSpanContext, {
         spanId: 'b7ad6b7169203331',
         traceId: '0af7651916cd43dd8448eb211c80319c',
+        isRemote: true,
         traceFlags: TraceFlags.SAMPLED,
         traceState: new TraceState('foo=bar,baz=qux,quux=quuz'),
       });

packages/opentelemetry-types/src/trace/span_context.ts

@@ -35,6 +35,10 @@ export interface SpanContext {
    * lowercase hex characters corresponding to 64 bits.
    */
   spanId: string;
+  /**
+   * Only true if the SpanContext was propagated from a remote parent.
+   */
+  isRemote?: boolean;
   /**
    * Trace flags to propagate.
    *