[frontend] reunite trace from loadgenerator (open-telemetry#1506)

CHANGELOG.md

@@ -9,6 +9,8 @@ the release.
 
 * [frauddetectionservice] use span links when consuming from Kafka
   ([#1501](https://github.com/open-telemetry/opentelemetry-demo/pull/1501))
+* [frontend] reunite trace from loadgenerator
+  ([#1506](https://github.com/open-telemetry/opentelemetry-demo/pull/1506))
 
 ## 1.9.0
 

src/frontend/utils/telemetry/InstrumentationMiddleware.ts

@@ -2,47 +2,19 @@
 // SPDX-License-Identifier: Apache-2.0
 
 import { NextApiHandler } from 'next';
-import { context, Exception, propagation, Span, SpanKind, SpanStatusCode, trace } from '@opentelemetry/api';
+import {context, Exception, Span, SpanStatusCode, trace} from '@opentelemetry/api';
 import { SemanticAttributes } from '@opentelemetry/semantic-conventions';
 import { metrics } from '@opentelemetry/api';
-import { AttributeNames } from '../enums/AttributeNames';
 
 const meter = metrics.getMeter('frontend');
 const requestCounter = meter.createCounter('app.frontend.requests');
 
 const InstrumentationMiddleware = (handler: NextApiHandler): NextApiHandler => {
   return async (request, response) => {
-    const { headers, method, url = '', httpVersion } = request;
+    const {method, url = ''} = request;
     const [target] = url.split('?');
 
-    let span;
-    const baggage = propagation.getBaggage(context.active());
-    if (baggage?.getEntry('synthetic_request')?.value == 'true') {
-      // if synthetic_request baggage is set, create a new trace linked to the span in context
-      // this span will look similar to the auto-instrumented HTTP span
-      const syntheticSpan = trace.getSpan(context.active()) as Span;
-      const tracer = trace.getTracer(process.env.OTEL_SERVICE_NAME as string);
-      span = tracer.startSpan(`HTTP ${method}`, {
-        root: true,
-        kind: SpanKind.SERVER,
-        links: [{ context: syntheticSpan.spanContext() }],
-        attributes: {
-          'app.synthetic_request': true,
-          [SemanticAttributes.HTTP_TARGET]: target,
-          [SemanticAttributes.HTTP_METHOD]: method,
-          [SemanticAttributes.HTTP_USER_AGENT]: headers['user-agent'] || '',
-          [SemanticAttributes.HTTP_URL]: `${headers.host}${url}`,
-          [SemanticAttributes.HTTP_FLAVOR]: httpVersion,
-        },
-      });
-    } else {
-      // continue current trace/span
-      span = trace.getSpan(context.active()) as Span;
-    }
-
-    if (request.query['sessionId'] != null) {
-      span.setAttribute(AttributeNames.SESSION_ID, request.query['sessionId']);
-    }
+    const span = trace.getSpan(context.active()) as Span;
 
     let httpStatus = 200;
     try {
@@ -56,9 +28,6 @@ const InstrumentationMiddleware = (handler: NextApiHandler): NextApiHandler => {
     } finally {
       requestCounter.add(1, { method, target, status: httpStatus });
       span.setAttribute(SemanticAttributes.HTTP_STATUS_CODE, httpStatus);
-      if (baggage?.getEntry('synthetic_request')?.value == 'true') {
-        span.end();
-      }
     }
   };
 };