feat: report url for lambda invoked via api gateway (#2404)

Co-authored-by: Marc Pichler <[email protected]>

Author: johnbley

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

@@ -37,8 +37,10 @@ import {
   TextMapGetter,
   TracerProvider,
   ROOT_CONTEXT,
+  Attributes,
 } from '@opentelemetry/api';
 import {
+  ATTR_URL_FULL,
   SEMATTRS_FAAS_EXECUTION,
   SEMRESATTRS_CLOUD_ACCOUNT_ID,
   SEMRESATTRS_FAAS_ID,
@@ -244,6 +246,7 @@ export class AwsLambdaInstrumentation extends InstrumentationBase<AwsLambdaInstr
                 context.invokedFunctionArn
               ),
             [ATTR_FAAS_COLDSTART]: requestIsColdStart,
+            ...AwsLambdaInstrumentation._extractOtherEventFields(event),
           },
         },
         parent
@@ -426,6 +429,52 @@ 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[ATTR_URL_FULL] = 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) {
+      return undefined;
+    }
+    // Helper function to deal with case variations (instead of making a tolower() copy of the headers)
+    function findAny(
+      event: any,
+      key1: string,
+      key2: string
+    ): string | undefined {
+      return event.headers[key1] ?? event.headers[key2];
+    }
+    const host = findAny(event, 'host', 'Host');
+    const proto = findAny(event, 'x-forwarded-proto', 'X-Forwarded-Proto');
+    const port = findAny(event, 'x-forwarded-port', 'X-Forwarded-Port');
+    if (!(proto && host && (event.path || event.rawPath))) {
+      return undefined;
+    }
+    let answer = proto + '://' + host;
+    if (port) {
+      answer += ':' + port;
+    }
+    answer += event.path ?? event.rawPath;
+    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;
+  }
+
   private static _determineParent(
     event: any,
     context: Context,

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

@@ -33,6 +33,7 @@ import { NodeTracerProvider } from '@opentelemetry/sdk-trace-node';
 import { Context } from 'aws-lambda';
 import * as assert from 'assert';
 import {
+  ATTR_URL_FULL,
   SEMATTRS_EXCEPTION_MESSAGE,
   SEMATTRS_FAAS_COLDSTART,
   SEMATTRS_FAAS_EXECUTION,
@@ -768,4 +769,52 @@ describe('lambda handler', () => {
       assert.strictEqual(span.parentSpanId, undefined);
     });
   });
+
+  describe('url parsing', () => {
+    it('pulls url from api gateway rest events', async () => {
+      initializeHandler('lambda-test/sync.handler');
+      const event = {
+        path: '/lambda/test/path',
+        headers: {
+          Host: 'www.example.com',
+          'X-Forwarded-Proto': 'http',
+          'X-Forwarded-Port': 1234,
+        },
+        queryStringParameters: {
+          key: 'value',
+          key2: 'value2',
+        },
+      };
+
+      await lambdaRequire('lambda-test/sync').handler(event, ctx, () => {});
+      const [span] = memoryExporter.getFinishedSpans();
+      assert.ok(
+        span.attributes[ATTR_URL_FULL] ===
+          'http://www.example.com:1234/lambda/test/path?key=value&key2=value2' ||
+          span.attributes[ATTR_URL_FULL] ===
+            'http://www.example.com:1234/lambda/test/path?key2=value2&key=value'
+      );
+    });
+    it('pulls url from api gateway http events', async () => {
+      initializeHandler('lambda-test/sync.handler');
+      const event = {
+        rawPath: '/lambda/test/path',
+        headers: {
+          host: 'www.example.com',
+          'x-forwarded-proto': 'http',
+          'x-forwarded-port': 1234,
+        },
+        queryStringParameters: {
+          key: 'value',
+        },
+      };
+
+      await lambdaRequire('lambda-test/sync').handler(event, ctx, () => {});
+      const [span] = memoryExporter.getFinishedSpans();
+      assert.strictEqual(
+        span.attributes[ATTR_URL_FULL],
+        'http://www.example.com:1234/lambda/test/path?key=value'
+      );
+    });
+  });
 });