feat(instrumentation-fetch): add option to apply attributes to all fe…

…tch spans
open-telemetry · Apr 2, 2021 · bb62ad3 · bb62ad3
1 parent 853fcb9
commit bb62ad3
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Showing 2 changed files with 43 additions and 2 deletions.
diff --git a/packages/opentelemetry-instrumentation-fetch/src/fetch.ts b/packages/opentelemetry-instrumentation-fetch/src/fetch.ts
@@ -19,6 +19,7 @@ import {
   isWrapped,
   InstrumentationBase,
   InstrumentationConfig,
+  safeExecuteInTheMiddle,
 } from '@opentelemetry/instrumentation';
 import * as core from '@opentelemetry/core';
 import * as web from '@opentelemetry/web';
@@ -43,6 +44,14 @@ const getUrlNormalizingAnchor = () => {
   return a;
 };
 
+export interface FetchCustomAttributeFunction {
+  (
+    span: api.Span,
+    request: Request | RequestInit,
+    result: Response | FetchError
+  ): void;
+}
+
 /**
  * FetchPlugin Config
  */
@@ -61,6 +70,8 @@ export interface FetchInstrumentationConfig extends InstrumentationConfig {
    * also not be traced.
    */
   ignoreUrls?: Array<string | RegExp>;
+  /** Function for adding custom attributes on the span */
+  applyCustomAttributesOnSpan?: FetchCustomAttributeFunction;
 }
 
 /**
@@ -187,14 +198,16 @@ export class FetchInstrumentation extends InstrumentationBase<
     }
     const method = (options.method || 'GET').toUpperCase();
     const spanName = `HTTP ${method}`;
-    return this.tracer.startSpan(spanName, {
+    const span = this.tracer.startSpan(spanName, {
       kind: api.SpanKind.CLIENT,
       attributes: {
         [AttributeNames.COMPONENT]: this.moduleName,
         [HttpAttribute.HTTP_METHOD]: method,
         [HttpAttribute.HTTP_URL]: url,
       },
     });
+
+    return span;
   }
 
   /**
@@ -306,6 +319,8 @@ export class FetchInstrumentation extends InstrumentationBase<
           response: Response
         ) {
           try {
+            plugin._applyAttributesAfterFetch(span, options, response);
+
             if (response.status >= 200 && response.status < 400) {
               plugin._endSpan(span, spanData, response);
             } else {
@@ -326,6 +341,7 @@ export class FetchInstrumentation extends InstrumentationBase<
           error: FetchError
         ) {
           try {
+            plugin._applyAttributesAfterFetch(span, options, error);
             plugin._endSpan(span, spanData, {
               status: error.status || 0,
               statusText: error.message,
@@ -355,6 +371,21 @@ export class FetchInstrumentation extends InstrumentationBase<
     };
   }
 
+  private _applyAttributesAfterFetch(
+    span: api.Span,
+    request: Request | RequestInit,
+    result: Response | FetchError
+  ) {
+    if (this._getConfig().applyCustomAttributesOnSpan) {
+      safeExecuteInTheMiddle(
+        () =>
+          this._getConfig().applyCustomAttributesOnSpan!(span, request, result),
+        () => {},
+        true
+      );
+    }
+  }
+
   /**
    * Prepares a span data - needed later for matching appropriate network
    *     resources

diff --git a/packages/opentelemetry-instrumentation-fetch/test/fetch.test.ts b/packages/opentelemetry-instrumentation-fetch/test/fetch.test.ts
@@ -57,6 +57,11 @@ const getData = (url: string, method?: string) =>
     },
   });
 
+const customAttributeFunction = (span: api.Span): void => {
+  span.setAttribute('span kind', api.SpanKind.CLIENT);
+  span.setAttribute('custom', 'custom-attribute-value');
+};
+
 const defaultResource = {
   connectEnd: 15,
   connectStart: 13,
@@ -285,7 +290,10 @@ describe('fetch', () => {
   describe('when request is successful', () => {
     beforeEach(done => {
       const propagateTraceHeaderCorsUrls = [url];
-      prepareData(done, url, { propagateTraceHeaderCorsUrls });
+      prepareData(done, url, {
+        propagateTraceHeaderCorsUrls,
+        applyCustomAttributesOnSpan: customAttributeFunction,
+      });
     });
 
     afterEach(() => {
@@ -368,6 +376,8 @@ describe('fetch', () => {
         `attributes ${HttpAttribute.HTTP_RESPONSE_CONTENT_LENGTH} is <= 0`
       );
 
+      assert.strictEqual(attributes['span kind'], api.SpanKind.CLIENT);
+
       assert.strictEqual(keys.length, 9, 'number of attributes is wrong');
     });