feat: makes execution id accessible in the user's code (#58)

Retrieves execution id from `Synthetic-Execution-Id` and allows it to be used in `syntheticCode`.

Author: tiffunky

packages/synthetics-sdk-api/package.json

@@ -16,6 +16,7 @@
     "@types/supertest": "^2.0.12",
     "chai": "^4.3.7",
     "express": "^4.18.2",
+    "node-mocks-http": "^1.13.0",
     "sinon": "^16.0.0",
     "supertest": "^6.3.3"
   },

packages/synthetics-sdk-api/src/handlers.ts

@@ -29,9 +29,14 @@ import { getInstrumentedLogger } from './auto_instrumentation';
 instantiateMetadata();
 
 const asyncFilenamePrefix = 'async ';
+const syntheticExecutionIdHeader = 'Synthetic-Execution-Id';
 const runSynthetic = async (
-  // eslint-disable-next-line  @typescript-eslint/no-explicit-any
-  syntheticCode: (args: { logger: Logger }) => any
+  syntheticCode: (args: {
+    logger: Logger;
+    executionId: string | undefined;
+    // eslint-disable-next-line  @typescript-eslint/no-explicit-any
+  }) => any,
+  executionId: string | undefined
 ) => {
   const logger = await getInstrumentedLogger();
   const startTime = new Date().toISOString();
@@ -40,7 +45,7 @@ const runSynthetic = async (
   const synthetic_generic_result = GenericResultV1.create();
 
   try {
-    await syntheticCode({ logger });
+    await syntheticCode({ logger, executionId });
     synthetic_generic_result.ok = true;
   } catch (err: unknown) {
     synthetic_generic_result.ok = false;
@@ -93,12 +98,18 @@ const runSynthetic = async (
  * returns the results via res.send
  */
 export function runSyntheticHandler(
-  // eslint-disable-next-line  @typescript-eslint/no-explicit-any
-  syntheticCode: (args: { logger: Logger }) => any
+  syntheticCode: (args: {
+    logger: Logger;
+    executionId: string | undefined;
+    // eslint-disable-next-line  @typescript-eslint/no-explicit-any
+  }) => any
 ) {
   // eslint-disable-next-line  @typescript-eslint/no-explicit-any
-  return async (req: Request, res: Response): Promise<any> =>
-    res.send(await runSynthetic(syntheticCode));
+  return async (req: Request, res: Response): Promise<any> => {
+    res.send(
+      await runSynthetic(syntheticCode, req.get(syntheticExecutionIdHeader))
+    );
+  };
 }
 
 export function firstUserErrorStackFrame(

packages/synthetics-sdk-api/test/unit/handlers.spec.ts

@@ -15,6 +15,7 @@
 import { SyntheticResult, runSyntheticHandler } from '../../src/index';
 import { AssertionError, expect } from 'chai';
 import { Request, Response } from 'express';
+import { createRequest } from 'node-mocks-http';
 import { firstUserErrorStackFrame } from '../../src/handlers';
 import ErrorStackParser = require('error-stack-parser');
 
@@ -24,13 +25,15 @@ describe('GCM Synthetics Handler', async () => {
     const handler = runSyntheticHandler(() => true);
 
     const runHandler = new Promise((resolve) => {
+      const mockRequest = createRequest({});
+
       let mockResponse = {
         send: (body: any) => {
           resolve(body);
         }
       } as Response;
 
-      handler({} as Request, mockResponse);
+      handler(mockRequest, mockResponse);
     });
 
     const syntheticResult = await runHandler as SyntheticResult;
@@ -53,13 +56,14 @@ describe('GCM Synthetics Handler', async () => {
     });
 
     const runHandler = new Promise((resolve) => {
+      const mockRequest = createRequest({});
       let mockResponse = {
         send: (body: any) => {
           resolve(body);
         }
       } as Response;
 
-      handler({} as Request, mockResponse);
+      handler(mockRequest, mockResponse);
     });
 
     const syntheticResult = await runHandler as SyntheticResult;
@@ -92,13 +96,14 @@ describe('GCM Synthetics Handler', async () => {
     const handler = runSyntheticHandler(handlerFunction);
 
     const runHandler = new Promise((resolve) => {
+      const mockRequest = createRequest({});
       let mockResponse = {
         send: (body: any) => {
           resolve(body);
         }
       } as Response;
 
-      handler({} as Request, mockResponse);
+      handler(mockRequest, mockResponse);
     });
 
     const syntheticResult = await runHandler as SyntheticResult;
@@ -153,4 +158,29 @@ describe('GCM Synthetics Handler', async () => {
         '    at async MyClass.Function (/user/my/file.js:6:11)');
     });
   });
+
+  it('has execution id available', async () => {
+    const executionId = 'deadbeefdeadbeefdeadbeefdeadbeef'
+    const handler = runSyntheticHandler((args: {executionId: string|undefined}) => {
+      expect(args.executionId).to.equal(executionId);
+    });
+
+    const runHandler = new Promise((resolve) => {
+      const mockRequest = createRequest({
+        headers: {"Synthetic-Execution-Id": executionId}
+      });
+
+      let mockResponse = {
+        send: (body: any) => {
+          resolve(body);
+        }
+      } as Response;
+
+      handler(mockRequest, mockResponse);
+    });
+
+    const syntheticResult = await runHandler as SyntheticResult;
+    expect(syntheticResult?.synthetic_generic_result_v1?.ok).to.be.true;
+    expect(syntheticResult?.synthetic_generic_result_v1?.generic_error).to.be.undefined;
+  });
 });