fix(instrumentation-fetch, instrumentation-xml-http-request) content length attributes missing

CHANGELOG_NEXT.md

@@ -17,6 +17,7 @@
 * refactor(sdk-trace-base)!: remove `new Span` constructor in favor of `Tracer.startSpan` API [#5048](https://github.com/open-telemetry/opentelemetry-js/pull/5048) @david-luna
 * refactor(sdk-trace-base)!: remove `BasicTracerProvider.addSpanProcessor` API in favor of constructor options. [#5134](https://github.com/open-telemetry/opentelemetry-js/pull/5134) @david-luna
 * refactor(sdk-trace-base)!: make `resource` property private in `BasicTracerProvider` and remove `getActiveSpanProcessor` API. [#5192](https://github.com/open-telemetry/opentelemetry-js/pull/5192) @david-luna
+* feat(sdk-trace-web)!: content length attributes are no longer added in `addSpanNetworkEvents`. Logic has been moved to new method `addSpanContentLengthAttributes` [#5257](https://github.com/open-telemetry/opentelemetry-js/pull/5257) @arriIsHere
 
 ### :rocket: (Enhancement)
 

experimental/packages/opentelemetry-instrumentation-fetch/src/fetch.ts

@@ -115,6 +115,7 @@ export class FetchInstrumentation extends InstrumentationBase<FetchInstrumentati
     if (!this.getConfig().ignoreNetworkEvents) {
       web.addSpanNetworkEvents(childSpan, corsPreFlightRequest);
     }
+    web.addSpanContentLengthAttributes(childSpan, corsPreFlightRequest);
     childSpan.end(
       corsPreFlightRequest[web.PerformanceTimingNames.RESPONSE_END]
     );
@@ -265,6 +266,7 @@ export class FetchInstrumentation extends InstrumentationBase<FetchInstrumentati
       if (!this.getConfig().ignoreNetworkEvents) {
         web.addSpanNetworkEvents(span, mainRequest);
       }
+      web.addSpanContentLengthAttributes(span, mainRequest);
     }
   }
 

experimental/packages/opentelemetry-instrumentation-fetch/test/fetch.test.ts

@@ -1211,5 +1211,18 @@ describe('fetch', () => {
       const events = span.events;
       assert.strictEqual(events.length, 0, 'number of events is wrong');
     });
+
+    it('should still add the CONTENT_LENGTH attribute', () => {
+      const span: tracing.ReadableSpan = exportSpy.args[1][0][0];
+      const attributes = span.attributes;
+      const responseContentLength = attributes[
+        SEMATTRS_HTTP_RESPONSE_CONTENT_LENGTH
+      ] as number;
+      assert.strictEqual(
+        responseContentLength,
+        30,
+        `attributes ${SEMATTRS_HTTP_RESPONSE_CONTENT_LENGTH} is <= 0`
+      );
+    });
   });
 });

experimental/packages/opentelemetry-instrumentation-xml-http-request/src/xhr.ts

@@ -37,6 +37,7 @@ import {
   PerformanceTimingNames as PTN,
   shouldPropagateTraceHeaders,
   parseUrl,
+  addSpanContentLengthAttributes,
 } from '@opentelemetry/sdk-trace-web';
 import { EventNames } from './enums/EventNames';
 import {
@@ -152,6 +153,7 @@ export class XMLHttpRequestInstrumentation extends InstrumentationBase<XMLHttpRe
       if (!this.getConfig().ignoreNetworkEvents) {
         addSpanNetworkEvents(childSpan, corsPreFlightRequest);
       }
+      addSpanContentLengthAttributes(childSpan, corsPreFlightRequest);
       childSpan.end(corsPreFlightRequest[PTN.RESPONSE_END]);
     });
   }
@@ -303,6 +305,7 @@ export class XMLHttpRequestInstrumentation extends InstrumentationBase<XMLHttpRe
       if (!this.getConfig().ignoreNetworkEvents) {
         addSpanNetworkEvents(span, mainRequest);
       }
+      addSpanContentLengthAttributes(span, mainRequest);
     }
   }
 

experimental/packages/opentelemetry-instrumentation-xml-http-request/test/xhr.test.ts

@@ -859,6 +859,19 @@ describe('xhr', () => {
             const events = span.events;
             assert.strictEqual(events.length, 3, 'number of events is wrong');
           });
+
+          it('should still add the CONTENT_LENGTH attribute', () => {
+            const span: tracing.ReadableSpan = exportSpy.args[1][0][0];
+            const attributes = span.attributes;
+            const responseContentLength = attributes[
+              SEMATTRS_HTTP_RESPONSE_CONTENT_LENGTH
+            ] as number;
+            assert.strictEqual(
+              responseContentLength,
+              30,
+              `attributes ${SEMATTRS_HTTP_RESPONSE_CONTENT_LENGTH} is <= 0`
+            );
+          });
         });
       });
 

packages/opentelemetry-sdk-trace-web/src/index.ts

@@ -27,6 +27,7 @@ export {
   URLLike,
   addSpanNetworkEvent,
   addSpanNetworkEvents,
+  addSpanContentLengthAttributes,
   getElementXPath,
   getResource,
   hasKey,

packages/opentelemetry-sdk-trace-web/src/utils.ts

@@ -111,6 +111,17 @@ export function addSpanNetworkEvents(
   addSpanNetworkEvent(span, PTN.REQUEST_START, resource);
   addSpanNetworkEvent(span, PTN.RESPONSE_START, resource);
   addSpanNetworkEvent(span, PTN.RESPONSE_END, resource);
+}
+
+/**
+ * Helper function for adding content length attributes to a network span
+ * @param span
+ * @param resource
+ */
+export function addSpanContentLengthAttributes(
+  span: api.Span,
+  resource: PerformanceEntries
+): void {
   const encodedLength = resource[PTN.ENCODED_BODY_SIZE];
   if (encodedLength !== undefined) {
     span.setAttribute(SEMATTRS_HTTP_RESPONSE_CONTENT_LENGTH, encodedLength);