add getTraceHeaders method to span

Author: lobsterkatie

packages/tracing/src/span.ts

@@ -1,5 +1,5 @@
 /* eslint-disable max-lines */
-import { Span as SpanInterface, SpanContext, Transaction } from '@sentry/types';
+import { Span as SpanInterface, SpanContext, TraceHeadersArr, TraceHeadersObj, Transaction } from '@sentry/types';
 import { dropUndefinedKeys, timestampWithMs, uuid4 } from '@sentry/utils';
 
 import { SpanStatus } from './spanstatus';
@@ -246,6 +246,31 @@ export class Span implements SpanInterface {
     return `${this.traceId}-${this.spanId}${sampledString}`;
   }
 
+  /**
+   * @inheritDoc
+   */
+  public getTraceHeaders(format: 'array' | 'object'): TraceHeadersArr | TraceHeadersObj {
+    let headers;
+    const traceparent = this.toTraceparent();
+    // tracestates live on the transaction, so if this is a free-floating span, there won't be one
+    const tracestate = this.transaction?.tracestate;
+
+    if (format === 'array') {
+      // headers = [['sentry-trace', traceparent], ...(tracestate && [['tracestate', tracestate]])];
+      headers = [['sentry-trace', traceparent]];
+      if (tracestate) {
+        headers.push(['tracestate', tracestate]);
+      }
+
+      return headers as TraceHeadersArr;
+    }
+
+    return {
+      'sentry-trace': traceparent,
+      ...(tracestate && { tracestate }),
+    } as TraceHeadersObj;
+  }
+
   /**
    * @inheritDoc
    */

packages/types/src/index.ts

@@ -21,7 +21,7 @@ export { CaptureContext, Scope, ScopeContext } from './scope';
 export { SdkInfo } from './sdkinfo';
 export { Session, SessionContext, SessionStatus } from './session';
 export { Severity } from './severity';
-export { Span, SpanContext } from './span';
+export { Span, SpanContext, TraceHeadersArr, TraceHeadersObj } from './span';
 export { StackFrame } from './stackframe';
 export { Stacktrace } from './stacktrace';
 export { Status } from './status';

packages/types/src/span.ts

@@ -148,6 +148,13 @@ export interface Span extends SpanContext {
   /** Return a traceparent compatible header string */
   toTraceparent(): string;
 
+  /**
+   * Get headers to attach to any outgoing requests made by the operation which created the span
+   *
+   * @returns An object containing the headers
+   */
+  getTraceHeaders(format: 'array' | 'object'): TraceHeadersArr | TraceHeadersObj;
+
   /** Convert the object to JSON for w. spans array info only */
   getTraceContext(): {
     data?: { [key: string]: any };
@@ -159,6 +166,7 @@ export interface Span extends SpanContext {
     tags?: { [key: string]: string };
     trace_id: string;
   };
+
   /** Convert the object to JSON */
   toJSON(): {
     data?: { [key: string]: any };
@@ -173,3 +181,10 @@ export interface Span extends SpanContext {
     trace_id: string;
   };
 }
+
+export type TraceHeadersArr = [['sentry-trace', string], ['tracestate', string]?];
+
+export type TraceHeadersObj = {
+  'sentry-trace': string;
+  tracestate?: string;
+};