chore: adding info to debug whenever headers are being skipped due to cors policy (#2061)

Co-authored-by: Valentin Marchaud <[email protected]>

Author: obecny

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

@@ -145,6 +145,11 @@ export class FetchInstrumentation extends InstrumentationBase<
         this._getConfig().propagateTraceHeaderCorsUrls
       )
     ) {
+      const headers: Partial<Record<string, unknown>> = {};
+      api.propagation.inject(api.context.active(), headers);
+      if (Object.keys(headers).length > 0) {
+        api.diag.debug('headers inject skipped due to CORS policy');
+      }
       return;
     }
 
@@ -292,8 +297,8 @@ export class FetchInstrumentation extends InstrumentationBase<
       ): Promise<Response> {
         const url = input instanceof Request ? input.url : input;
         const options = input instanceof Request ? input : init || {};
-        const span = plugin._createSpan(url, options);
-        if (!span) {
+        const createdSpan = plugin._createSpan(url, options);
+        if (!createdSpan) {
           return original.apply(this, [url, options]);
         }
         const spanData = plugin._prepareSpanData(url);
@@ -338,15 +343,15 @@ export class FetchInstrumentation extends InstrumentationBase<
 
         return new Promise((resolve, reject) => {
           return api.context.with(
-            api.setSpan(api.context.active(), span),
+            api.setSpan(api.context.active(), createdSpan),
             () => {
               plugin._addHeaders(options, url);
               plugin._tasksCount++;
               return original
                 .apply(this, [url, options])
                 .then(
-                  (onSuccess as any).bind(this, span, resolve),
-                  onError.bind(this, span, reject)
+                  (onSuccess as any).bind(this, createdSpan, resolve),
+                  onError.bind(this, createdSpan, reject)
                 );
             }
           );

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

@@ -537,10 +537,19 @@ describe('fetch', () => {
     });
 
     describe('when propagateTraceHeaderCorsUrls does NOT MATCH', () => {
+      let spyDebug: sinon.SinonSpy;
       beforeEach(done => {
+        const diagLogger = new api.DiagConsoleLogger();
+        spyDebug = sinon.spy();
+        diagLogger.debug = spyDebug;
+        api.diag.setLogger(diagLogger, api.DiagLogLevel.ALL);
         clearData();
         prepareData(done, url, {});
       });
+      afterEach(() => {
+        sinon.restore();
+      });
+
       it('should NOT set trace headers', () => {
         assert.strictEqual(
           lastResponse.headers[X_B3_TRACE_ID],
@@ -558,6 +567,12 @@ describe('fetch', () => {
           `trace header '${X_B3_SAMPLED}' should not be set`
         );
       });
+      it('should debug info that injecting headers was skipped', () => {
+        assert.strictEqual(
+          spyDebug.lastCall.args[0],
+          'headers inject skipped due to CORS policy'
+        );
+      });
     });
   });
 

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

@@ -106,6 +106,11 @@ export class XMLHttpRequestInstrumentation extends InstrumentationBase<XMLHttpRe
         this._getConfig().propagateTraceHeaderCorsUrls
       )
     ) {
+      const headers: Partial<Record<string, unknown>> = {};
+      api.propagation.inject(api.context.active(), headers);
+      if (Object.keys(headers).length > 0) {
+        api.diag.debug('headers inject skipped due to CORS policy');
+      }
       return;
     }
     const headers: { [key: string]: unknown } = {};

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

@@ -549,7 +549,12 @@ describe('xhr', () => {
           'AND origin does NOT match window.location And does NOT match' +
             ' with propagateTraceHeaderCorsUrls',
           () => {
+            let spyDebug: sinon.SinonSpy;
             beforeEach(done => {
+              const diagLogger = new api.DiagConsoleLogger();
+              spyDebug = sinon.spy();
+              diagLogger.debug = spyDebug;
+              api.diag.setLogger(diagLogger, api.DiagLogLevel.ALL);
               clearData();
               prepareData(
                 done,
@@ -573,6 +578,13 @@ describe('xhr', () => {
                 `trace header '${X_B3_SAMPLED}' should not be set`
               );
             });
+
+            it('should debug info that injecting headers was skipped', () => {
+              assert.strictEqual(
+                spyDebug.lastCall.args[0],
+                'headers inject skipped due to CORS policy'
+              );
+            });
           }
         );