feat: report url for lambda invoked via api gateway

Author: johnbley

plugins/node/opentelemetry-instrumentation-aws-lambda/src/instrumentation.ts

@@ -38,13 +38,15 @@ import {
   TraceFlags,
   TracerProvider,
   ROOT_CONTEXT,
+  Attributes,
 } from '@opentelemetry/api';
 import {
   AWSXRAY_TRACE_ID_HEADER,
   AWSXRayPropagator,
 } from '@opentelemetry/propagator-aws-xray';
 import {
   SEMATTRS_FAAS_EXECUTION,
+  SEMATTRS_HTTP_URL,
   SEMRESATTRS_CLOUD_ACCOUNT_ID,
   SEMRESATTRS_FAAS_ID,
 } from '@opentelemetry/semantic-conventions';
@@ -203,6 +205,7 @@ export class AwsLambdaInstrumentation extends InstrumentationBase<AwsLambdaInstr
               AwsLambdaInstrumentation._extractAccountId(
                 context.invokedFunctionArn
               ),
+            ...AwsLambdaInstrumentation._extractOtherEventFields(event),
           },
         },
         parent
@@ -385,6 +388,41 @@ export class AwsLambdaInstrumentation extends InstrumentationBase<AwsLambdaInstr
     return propagation.extract(otelContext.active(), httpHeaders, headerGetter);
   }
 
+  private static _extractOtherEventFields(event: any): Attributes {
+    const answer: Attributes = {};
+    const fullUrl = this._extractFullUrl(event);
+    if (fullUrl) {
+      answer[SEMATTRS_HTTP_URL] = fullUrl;
+    }
+    return answer;
+  }
+
+  private static _extractFullUrl(event: any): string | undefined {
+    // API gateway encodes a lot of url information in various places to recompute this
+    if (!event.headers || !event.path) {
+      return undefined;
+    }
+    let answer = '';
+    if (event.headers['x-forwarded-proto']) {
+      answer += event.headers['x-forwarded-proto'] + '://';
+    }
+    if (event.headers['host']) {
+      answer += event.headers['host'];
+    }
+    answer += event.path;
+    if (event.queryStringParameters) {
+      let first = true;
+      for (const key in event.queryStringParameters) {
+        answer += first ? '?' : '&';
+        answer += encodeURIComponent(key);
+        answer += '=';
+        answer += encodeURIComponent(event.queryStringParameters[key]);
+        first = false;
+      }
+    }
+    return answer.length === 0 ? undefined : answer;
+  }
+
   private static _determineParent(
     event: any,
     context: Context,

plugins/node/opentelemetry-instrumentation-aws-lambda/test/integrations/lambda-handler.test.ts

@@ -35,6 +35,7 @@ import * as assert from 'assert';
 import {
   SEMATTRS_EXCEPTION_MESSAGE,
   SEMATTRS_FAAS_EXECUTION,
+  SEMATTRS_HTTP_URL,
   SEMRESATTRS_FAAS_NAME,
 } from '@opentelemetry/semantic-conventions';
 import {
@@ -983,4 +984,28 @@ describe('lambda handler', () => {
       assert.strictEqual(span.parentSpanId, undefined);
     });
   });
+
+  describe('url parsing', () => {
+    it('pulls url from api gateway events', async () => {
+      initializeHandler('lambda-test/sync.handler');
+      const event = {
+        path: '/lambda/test/path',
+        headers: {
+          host: 'www.example.com',
+          'x-forwarded-proto': 'http',
+        },
+        queryStringParameters: {
+          key: 'value',
+        },
+      };
+
+      await lambdaRequire('lambda-test/sync').handler(event, ctx, () => {});
+      const [span] = memoryExporter.getFinishedSpans();
+      assert.strictEqual(
+        span.attributes[SEMATTRS_HTTP_URL],
+        'http://www.example.com/lambda/test/path?key=value'
+      );
+      console.log(span);
+    });
+  });
 });