Instrument fetch

package.json

@@ -41,7 +41,7 @@
     "@typescript-eslint/eslint-plugin": "^5.61.0",
     "@typescript-eslint/parser": "^5.61.0",
     "@vitest/ui": "^0.34.1",
-    "axios": "^1.4.0",
+    "axios": "^1.7.1",
     "dotenv": "^16.3.1",
     "eslint": "^8.44.0",
     "eslint-config-semistandard": "^17.0.0",

playground/app.js

@@ -8,7 +8,7 @@ const express = require('express');
 const {
   OpenAPM,
   setOpenAPMLabels,
-  metricClient
+  getMetricClient
 } = require('../dist/src/index.js');
 const mysql2 = require('mysql2');
 
@@ -41,7 +41,7 @@ const pool = mysql2.createPool(
   'mysql://express-app:password@127.0.0.1/express' //  If this throws an error, Change the db url to the one you're running on your machine locally or the testing instance you might have hosted.
 );
 
-const client = metricClient();
+const client = getMetricClient();
 const counter = new client.Counter({
   name: 'cancelation_calls',
   help: 'no. of times cancel operation is called'
@@ -77,6 +77,19 @@ app.post('/api/v2/product/search/:term', (req, res) => {
   res.status(200).json({});
 });
 
+app.get('/cat-facts', async (req, res) => {
+  const catFacts = await fetch('https://cat-fact.herokuapp.com/facts', {
+    method: 'GET',
+    headers: {
+      'Content-Type': 'application/json'
+    }
+  })
+    .then((res) => res.json())
+    .then((json) => json.all);
+
+  res.status(200).json(catFacts);
+});
+
 app.all('/api/v1/slug/:slug', (req, res) => {
   setOpenAPMLabels({ slug: req.params.slug });
   res.status(200).json({});

src/OpenAPM.ts

@@ -13,12 +13,13 @@ import type {
 import type { NextFunction, Request, Response } from 'express';
 import type { IncomingMessage, ServerResponse, Server } from 'http';
 
-import { getHostIpAddress, getPackageJson, getSanitizedPath } from './utils';
+import { getPackageJson, getSanitizedPath } from './utils';
 
 import { instrumentExpress } from './clients/express';
 import { instrumentMySQL } from './clients/mysql2';
 import { instrumentNestFactory } from './clients/nestjs';
 import { instrumentNextjs } from './clients/nextjs';
+import { instrumentFetch } from './clients/fetch';
 
 import { LevitateConfig, LevitateEvents } from './levitate/events';
 import {
@@ -32,11 +33,7 @@ export type ExtractFromParams = {
   mask: string;
 };
 
-export type DefaultLabels =
-  | 'environment'
-  | 'program'
-  | 'version'
-  | 'host';
+export type DefaultLabels = 'environment' | 'program' | 'version' | 'host';
 
 export interface OpenAPMOptions {
   /**
@@ -142,6 +139,7 @@ export class OpenAPM extends LevitateEvents {
     if (this.enabled) {
       this.initiateMetricsRoute();
       this.initiatePromClient();
+      this.instrumentThirdParty();
     }
   }
 
@@ -186,7 +184,7 @@ export class OpenAPM extends LevitateEvents {
       environment: this.environment,
       program: packageJson?.name ?? '',
       version: packageJson?.version ?? '',
-      host: os.hostname(),      
+      host: os.hostname(),
       ...this.defaultLabels
     };
 
@@ -416,6 +414,30 @@ export class OpenAPM extends LevitateEvents {
     return metrics.trim();
   };
 
+  private instrumentThirdParty = () => {
+    // wrap(http, 'request', (original): typeof http.request => {
+    //   return function (
+    //     this: typeof original,
+    //     ...args: Parameters<typeof original>
+    //   ) {
+    //     console.log('OpenAPM: http.request', args);
+    //     return original.apply(this, args);
+    //   } as typeof http.request;
+    // });
+
+    // wrap(https, 'request', (original): typeof http.request => {
+    //   return function (
+    //     this: typeof original,
+    //     ...args: Parameters<typeof original>
+    //   ) {
+    //     console.log('OpenAPM: http.request', args);
+    //     return original.apply(this, args);
+    //   } as typeof http.request;
+    // });
+
+    instrumentFetch();
+  };
+
   public instrument(moduleName: SupportedModules): boolean {
     if (!this.enabled) {
       return false;
@@ -469,8 +491,4 @@ export class OpenAPM extends LevitateEvents {
   }
 }
 
-export function getMetricClient() {
-  return promClient;
-}
-
 export default OpenAPM;

src/clients/fetch.ts

@@ -0,0 +1,55 @@
+import { getMetricClient } from '../get-metric-client';
+import { wrap } from '../shimmer';
+
+export const instrumentFetch = () => {
+  const client = getMetricClient();
+
+  const counter = new client.Counter({
+    name: 'fetch_requests_total',
+    help: 'Monitor the number of fetch requests made by the application to external services',
+    labelNames: ['method', 'status', 'origin']
+  });
+
+  const histogram = new client.Histogram({
+    name: 'fetch_duration_milliseconds',
+    help: 'Monitor the duration of fetch requests made by the application to external services',
+    labelNames: ['method', 'status', 'origin']
+  });
+
+  wrap(globalThis, 'fetch', (originalFetch): typeof globalThis.fetch => {
+    return async function (
+      this: typeof originalFetch,
+      ...args: Parameters<typeof originalFetch>
+    ) {
+      const start = process.hrtime.bigint();
+      const result = originalFetch.apply(this, args);
+
+      if (result instanceof Promise) {
+        await result;
+      }
+      const end = process.hrtime.bigint();
+      const duration = Number(end - start) / 1e6;
+
+      const origin = new URL(args[0].toString()).origin;
+
+      counter.inc({
+        method: args[1]?.method ?? 'GET',
+        // @ts-ignore
+        status: result.status as string,
+        origin: origin.toString()
+      });
+
+      histogram.observe(
+        {
+          method: args[1]?.method ?? 'GET',
+          // @ts-ignore
+          status: result.status as string,
+          origin: origin.toString()
+        },
+        duration
+      );
+
+      return result;
+    } as typeof fetch;
+  });
+};

src/get-metric-client.ts

@@ -0,0 +1,5 @@
+import promClient from 'prom-client';
+
+export function getMetricClient() {
+  return promClient;
+}

src/index.ts

@@ -1,3 +1,4 @@
-export { default as OpenAPM, getMetricClient } from './OpenAPM';
+export { getMetricClient } from './get-metric-client';
+export { default as OpenAPM } from './OpenAPM';
 export { setOpenAPMLabels } from './async-local-storage.http';
 export type { OpenAPMOptions } from './OpenAPM';

tests/express.test.ts

@@ -1,7 +1,8 @@
 import express, { Express } from 'express';
 import { test, expect, describe, beforeAll, afterAll } from 'vitest';
 
-import OpenAPM, { getMetricClient } from '../src/OpenAPM';
+import OpenAPM from '../src/OpenAPM';
+import { getMetricClient } from '../src/get-metric-client';
 import { addRoutes, makeRequest, sendTestRequests } from './utils';
 import prom from 'prom-client';
 
@@ -28,7 +29,7 @@ describe('REDMiddleware', () => {
     addRoutes(app);
     app.listen(3002);
 
-    const out = await sendTestRequests(app, NUMBER_OF_REQUESTS);
+    // const out = await sendTestRequests(app, NUMBER_OF_REQUESTS);
   });
 
   afterAll(async () => {
@@ -38,8 +39,6 @@ describe('REDMiddleware', () => {
     });
   });
 
-  test;
-
   test('Captures Counter Metrics - App', async () => {
     const parsedData = await getMetrics();
 
@@ -142,4 +141,9 @@ describe('REDMiddleware', () => {
       metricValues?.find((m) => m.labels.path === '/api/labels/:id')?.labels.id
     ).toBe('123');
   });
+
+  test('Third Party call instrumentation', async () => {
+    const res = await makeRequest(app, '/cat-facts');
+    expect(true).toBe(true);
+  });
 });

tests/utils.ts

@@ -1,8 +1,9 @@
 import request from 'supertest';
 import express from 'express';
+import axios from 'axios';
 import type { Express } from 'express';
 import { setOpenAPMLabels } from '../src/async-local-storage.http';
-import { getMetricClient } from '../src/OpenAPM';
+import { getMetricClient } from '../src/get-metric-client';
 
 export const addRoutes = (app: Express) => {
   const router = express.Router();
@@ -41,6 +42,19 @@ export const addRoutes = (app: Express) => {
     res.status(200).send(id);
   });
 
+  app.get('/cat-facts', async (req, res) => {
+    const catFacts = await fetch('https://cat-fact.herokuapp.com/facts', {
+      method: 'GET',
+      headers: {
+        'Content-Type': 'application/json'
+      }
+    })
+      .then((res) => res.json())
+      .then((json) => json.all);
+
+    res.status(200).send(catFacts);
+  });
+
   return app;
 };