Propagate b3 parentspanid and debug flag

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

@@ -49,7 +49,7 @@ export interface SpanContext {
    *
    * SAMPLED = 0x1 and NONE = 0x0;
    */
-  traceFlags: TraceFlags;
+  traceFlags?: TraceFlags;
   /**
    * Tracing-system-specific info to propagate.
    *

packages/opentelemetry-core/src/context/propagation/B3Propagator.ts

@@ -26,9 +26,19 @@ import { getParentSpanContext, setExtractedSpanContext } from '../context';
 export const X_B3_TRACE_ID = 'x-b3-traceid';
 export const X_B3_SPAN_ID = 'x-b3-spanid';
 export const X_B3_SAMPLED = 'x-b3-sampled';
+export const X_B3_PARENT_SPAN_ID = 'x-b3-parentspanid';
+export const X_B3_FLAGS = 'x-b3-flags';
+export const PARENT_SPAN_ID_KEY = Context.createKey(
+  'OpenTelemetry Context Key B3 Parent Span Id'
+);
+export const DEBUG_FLAG_KEY = Context.createKey(
+  'OpenTelemetry Context Key B3 Debug Flag'
+);
 const VALID_TRACEID_REGEX = /^([0-9a-f]{16}){1,2}$/i;
 const VALID_SPANID_REGEX = /^[0-9a-f]{16}$/i;
 const INVALID_ID_REGEX = /^0+$/i;
+const VALID_SAMPLED_VALUES = [true, 'true', '1', 1];
+const VALID_UNSAMPLED_VALUES = [0, '0', 'false', false];
 
 function isValidTraceId(traceId: string): boolean {
   return VALID_TRACEID_REGEX.test(traceId) && !INVALID_ID_REGEX.test(traceId);
@@ -38,25 +48,106 @@ function isValidSpanId(spanId: string): boolean {
   return VALID_SPANID_REGEX.test(spanId) && !INVALID_ID_REGEX.test(spanId);
 }
 
+function isValidParentSpanID(spanId: string | undefined): boolean {
+  return spanId === undefined || isValidSpanId(spanId);
+}
+
+function isValidSampledValue(sampled: number | undefined): boolean {
+  return (
+    sampled === undefined ||
+    VALID_SAMPLED_VALUES.includes(sampled) ||
+    VALID_UNSAMPLED_VALUES.includes(sampled)
+  );
+}
+
+function parseHeader(header: unknown) {
+  return Array.isArray(header) ? header[0] : header;
+}
+
 /**
  * Propagator for the B3 HTTP header format.
  * Based on: https://github.com/openzipkin/b3-propagation
  */
 export class B3Propagator implements HttpTextPropagator {
+  _getHeaderValue(carrier: unknown, getter: GetterFunction, key: string) {
+    const header = getter(carrier, key);
+    return parseHeader(header);
+  }
+
+  _getTraceId(carrier: unknown, getter: GetterFunction): string {
+    const traceId = this._getHeaderValue(carrier, getter, X_B3_TRACE_ID);
+    if (typeof traceId === 'string') {
+      return traceId.padStart(32, '0');
+    }
+    return '';
+  }
+
+  _getSpanId(carrier: unknown, getter: GetterFunction): string {
+    const spanId = this._getHeaderValue(carrier, getter, X_B3_SPAN_ID);
+    if (typeof spanId === 'string') {
+      return spanId;
+    }
+    return '';
+  }
+
+  _getParentSpanId(
+    carrier: unknown,
+    getter: GetterFunction
+  ): string | undefined {
+    const spanId = this._getHeaderValue(carrier, getter, X_B3_PARENT_SPAN_ID);
+    if (typeof spanId === 'string') {
+      return spanId;
+    }
+    return;
+  }
+
+  _getDebug(carrier: unknown, getter: GetterFunction): string | undefined {
+    const debug = this._getHeaderValue(carrier, getter, X_B3_FLAGS);
+    return debug === '1' ? '1' : undefined;
+  }
+
+  _getTraceFlags(carrier: unknown, getter: GetterFunction): number | undefined {
+    const traceFlags = this._getHeaderValue(carrier, getter, X_B3_SAMPLED);
+    const debug = this._getDebug(carrier, getter);
+    if (debug === '1') {
+      return TraceFlags.SAMPLED;
+    } else if (traceFlags !== undefined) {
+      if (VALID_SAMPLED_VALUES.includes(traceFlags)) {
+        return TraceFlags.SAMPLED;
+      } else if (VALID_UNSAMPLED_VALUES.includes(traceFlags)) {
+        return TraceFlags.NONE;
+      } else {
+        // Invalid traceflag
+        return 2;
+      }
+    }
+    return;
+  }
+
   inject(context: Context, carrier: unknown, setter: SetterFunction) {
     const spanContext = getParentSpanContext(context);
     if (!spanContext) return;
-
+    const parentSpanId = context.getValue(PARENT_SPAN_ID_KEY) as
+      | undefined
+      | string;
     if (
       isValidTraceId(spanContext.traceId) &&
-      isValidSpanId(spanContext.spanId)
+      isValidSpanId(spanContext.spanId) &&
+      isValidParentSpanID(parentSpanId)
     ) {
+      const debug = context.getValue(DEBUG_FLAG_KEY);
       setter(carrier, X_B3_TRACE_ID, spanContext.traceId);
       setter(carrier, X_B3_SPAN_ID, spanContext.spanId);
-
-      // We set the header only if there is an existing sampling decision.
-      // Otherwise we will omit it => Absent.
-      if (spanContext.traceFlags !== undefined) {
+      if (parentSpanId) {
+        setter(carrier, X_B3_PARENT_SPAN_ID, parentSpanId);
+      }
+      // According to the B3 spec, if the debug flag is set,
+      // the sampled flag shouldn't be propagated as well.
+      if (debug === '1') {
+        setter(carrier, X_B3_FLAGS, debug);
+      } else if (spanContext.traceFlags !== undefined) {
+        // We set the header only if there is an existing sampling decision.
+        // Otherwise we will omit it => Absent.
         setter(
           carrier,
           X_B3_SAMPLED,
@@ -69,31 +160,25 @@ export class B3Propagator implements HttpTextPropagator {
   }
 
   extract(context: Context, carrier: unknown, getter: GetterFunction): Context {
-    const traceIdHeader = getter(carrier, X_B3_TRACE_ID);
-    const spanIdHeader = getter(carrier, X_B3_SPAN_ID);
-    const sampledHeader = getter(carrier, X_B3_SAMPLED);
-
-    const traceIdHeaderValue = Array.isArray(traceIdHeader)
-      ? traceIdHeader[0]
-      : traceIdHeader;
-    const spanId = Array.isArray(spanIdHeader) ? spanIdHeader[0] : spanIdHeader;
-
-    const options = Array.isArray(sampledHeader)
-      ? sampledHeader[0]
-      : sampledHeader;
-
-    if (typeof traceIdHeaderValue !== 'string' || typeof spanId !== 'string') {
-      return context;
-    }
-
-    const traceId = traceIdHeaderValue.padStart(32, '0');
+    const traceId = this._getTraceId(carrier, getter);
+    const spanId = this._getSpanId(carrier, getter);
+    const parentSpanId = this._getParentSpanId(carrier, getter);
+    const traceFlags = this._getTraceFlags(carrier, getter);
+    const debug = this._getDebug(carrier, getter);
 
-    if (isValidTraceId(traceId) && isValidSpanId(spanId)) {
+    if (
+      isValidTraceId(traceId) &&
+      isValidSpanId(spanId) &&
+      isValidParentSpanID(parentSpanId) &&
+      isValidSampledValue(traceFlags)
+    ) {
+      context = context.setValue(PARENT_SPAN_ID_KEY, parentSpanId);
+      context = context.setValue(DEBUG_FLAG_KEY, debug);
       return setExtractedSpanContext(context, {
         traceId,
         spanId,
         isRemote: true,
-        traceFlags: isNaN(Number(options)) ? TraceFlags.NONE : Number(options),
+        traceFlags,
       });
     }
     return context;

packages/opentelemetry-core/src/trace/sampler/ParentOrElseSampler.ts

@@ -41,7 +41,7 @@ export class ParentOrElseSampler implements Sampler {
     links: Link[]
   ): SamplingResult {
     // Respect the parent sampling decision if there is one
-    if (parentContext) {
+    if (parentContext && parentContext.traceFlags !== undefined) {
       return {
         decision:
           (TraceFlags.SAMPLED & parentContext.traceFlags) === TraceFlags.SAMPLED

packages/opentelemetry-core/src/trace/sampler/ProbabilitySampler.ts

@@ -31,7 +31,7 @@ export class ProbabilitySampler implements Sampler {
   shouldSample(parentContext?: SpanContext): SamplingResult {
     // Respect the parent sampling decision if there is one.
     // TODO(#1284): add an option to ignore parent regarding to spec.
-    if (parentContext) {
+    if (parentContext && parentContext.traceFlags !== undefined) {
       return {
         decision:
           (TraceFlags.SAMPLED & parentContext.traceFlags) === TraceFlags.SAMPLED