feat(core): Read propagation context off scopes in startSpan APIs

packages/core/src/tracing/trace.ts

@@ -5,6 +5,7 @@ import { dropUndefinedKeys, logger, tracingContextFromHeaders } from '@sentry/ut
 import { DEBUG_BUILD } from '../debug-build';
 import { getCurrentScope, withScope } from '../exports';
 import type { Hub } from '../hub';
+import { getIsolationScope } from '../hub';
 import { getCurrentHub } from '../hub';
 import { handleCallbackErrors } from '../utils/handleCallbackErrors';
 import { hasTracingEnabled } from '../utils/hasTracingEnabled';
@@ -172,11 +173,32 @@ export function startInactiveSpan(context: StartSpanOptions): Span | undefined {
     ? // eslint-disable-next-line deprecation/deprecation
       context.scope.getSpan()
     : getActiveSpan();
-  return parentSpan
-    ? // eslint-disable-next-line deprecation/deprecation
-      parentSpan.startChild(ctx)
-    : // eslint-disable-next-line deprecation/deprecation
-      hub.startTransaction(ctx);
+
+  if (parentSpan) {
+    // eslint-disable-next-line deprecation/deprecation
+    return parentSpan.startChild(ctx);
+  } else {
+    const isolationScope = getIsolationScope();
+    const scope = getCurrentScope();
+
+    const { traceId, dsc, parentSpanId, sampled } = {
+      ...isolationScope.getPropagationContext(),
+      ...scope.getPropagationContext(),
+    };
+
+    // eslint-disable-next-line deprecation/deprecation
+    return hub.startTransaction({
+      traceId,
+      parentSpanId,
+      parentSampled: sampled,
+      ...ctx,
+      metadata: {
+        dynamicSamplingContext: dsc,
+        // eslint-disable-next-line deprecation/deprecation
+        ...ctx.metadata,
+      },
+    });
+  }
 }
 
 /**
@@ -256,11 +278,32 @@ function createChildSpanOrTransaction(
   if (!hasTracingEnabled()) {
     return undefined;
   }
-  return parentSpan
-    ? // eslint-disable-next-line deprecation/deprecation
-      parentSpan.startChild(ctx)
-    : // eslint-disable-next-line deprecation/deprecation
-      hub.startTransaction(ctx);
+
+  if (parentSpan) {
+    // eslint-disable-next-line deprecation/deprecation
+    return parentSpan.startChild(ctx);
+  } else {
+    const isolationScope = getIsolationScope();
+    const scope = getCurrentScope();
+
+    const { traceId, dsc, parentSpanId, sampled } = {
+      ...isolationScope.getPropagationContext(),
+      ...scope.getPropagationContext(),
+    };
+
+    // eslint-disable-next-line deprecation/deprecation
+    return hub.startTransaction({
+      traceId,
+      parentSpanId,
+      parentSampled: sampled,
+      ...ctx,
+      metadata: {
+        dynamicSamplingContext: dsc,
+        // eslint-disable-next-line deprecation/deprecation
+        ...ctx.metadata,
+      },
+    });
+  }
 }
 
 /**

packages/core/test/lib/tracing/trace.test.ts

@@ -5,6 +5,7 @@ import {
   getCurrentScope,
   makeMain,
   spanToJSON,
+  withScope,
 } from '../../../src';
 import { Scope } from '../../../src/scope';
 import {
@@ -318,6 +319,22 @@ describe('startSpan', () => {
     expect(getCurrentScope()).toBe(initialScope);
     expect(getActiveSpan()).toBe(undefined);
   });
+
+  it("picks up the trace id off the parent scope's propagation context", () => {
+    expect.assertions(1);
+    withScope(scope => {
+      scope.setPropagationContext({
+        traceId: '99999999999999999999999999999999',
+        spanId: '1212121212121212',
+        dsc: {},
+        parentSpanId: '4242424242424242',
+      });
+
+      startSpan({ name: 'span' }, span => {
+        expect(span?.spanContext().traceId).toBe('99999999999999999999999999999999');
+      });
+    });
+  });
 });
 
 describe('startSpanManual', () => {
@@ -381,6 +398,23 @@ describe('startSpanManual', () => {
 
     expect(start).toEqual(1234);
   });
+
+  it("picks up the trace id off the parent scope's propagation context", () => {
+    expect.assertions(1);
+    withScope(scope => {
+      scope.setPropagationContext({
+        traceId: '99999999999999999999999999999991',
+        spanId: '1212121212121212',
+        dsc: {},
+        parentSpanId: '4242424242424242',
+      });
+
+      startSpanManual({ name: 'span' }, span => {
+        expect(span?.spanContext().traceId).toBe('99999999999999999999999999999991');
+        span?.end();
+      });
+    });
+  });
 });
 
 describe('startInactiveSpan', () => {
@@ -429,6 +463,22 @@ describe('startInactiveSpan', () => {
     const span = startInactiveSpan({ name: 'outer', startTime: [1234, 0] });
     expect(spanToJSON(span!).start_timestamp).toEqual(1234);
   });
+
+  it("picks up the trace id off the parent scope's propagation context", () => {
+    expect.assertions(1);
+    withScope(scope => {
+      scope.setPropagationContext({
+        traceId: '99999999999999999999999999999991',
+        spanId: '1212121212121212',
+        dsc: {},
+        parentSpanId: '4242424242424242',
+      });
+
+      const span = startInactiveSpan({ name: 'span' });
+      expect(span?.spanContext().traceId).toBe('99999999999999999999999999999991');
+      span?.end();
+    });
+  });
 });
 
 describe('continueTrace', () => {