Application Insights Express Middleware

0.0.5 verified Fri May 01 auth: no javascript deprecated

A package that monkey-patches Express and the Application Insights SDK for Node.js to automatically track Express middleware execution as dependency telemetry. It provides a setAutoCollectExpressMiddleware() method to enable collection, sending trackDependency() calls with middleware names and durations. Current version 0.0.5, last updated in May 2020. This is an early-stage project with no production guarantee; it is a WIP and likely has bugs. It targets the deprecated Azure Application Insights SDK and is not maintained actively. Consider the official @opentelemetry/instrumentation-express and @azure/monitor-opentelemetry for modern use cases.

Common errors

error TypeError: appInsights.setAutoCollectExpressMiddleware is not a function ↓

cause The middleware package was not required (or required after applicationinsights), so the method was not added to appInsights object.

fix

Ensure you require('applicationinsights-express-middleware') before const appInsights = require('applicationinsights').

error Error: Cannot find module 'applicationinsights-express-middleware' ↓

cause Package not installed or missing from node_modules.

fix

Run npm install applicationinsights-express-middleware.

error Cannot read properties of undefined (reading 'trackDependency') ↓

cause Application Insights not started or not configured properly.

fix

Call appInsights.setup('key').start() after requiring the middleware package.

Warnings

deprecated Project is abandoned; last release in 2020. Uses deprecated Azure Application Insights SDK. ↓

fix Migrate to @opentelemetry/instrumentation-express and @azure/monitor-opentelemetry.

breaking v0.0.5 renamed 'wrap' to 'patch' internally; API unchanged but internal monkey-patching changed. ↓

fix Update your code to use the new internal names if you relied on undocumented internals.

gotcha Must require this package before both applicationinsights and express. ↓

fix Reorder requires: require('applicationinsights-express-middleware') first, then applicationinsights, then express.

gotcha No support for dispose(); cannot stop instrumentation once started. ↓

fix Restart the application to stop tracking.

deprecated Azure Application Insights SDK is deprecated in favor of OpenTelemetry-based SDK. ↓

fix Use @azure/monitor-opentelemetry with @opentelemetry/instrumentation-express instead.

Install

npm install applicationinsights-express-middleware

yarn add applicationinsights-express-middleware

pnpm add applicationinsights-express-middleware

Imports

default

wrong

import applicationinsightsExpress from 'applicationinsights-express-middleware'

correct

require('applicationinsights-express-middleware')

This package has no default export; side-effect require only.

setAutoCollectExpressMiddleware

wrong

require('applicationinsights-express-middleware').setAutoCollectExpressMiddleware(true)

correct

appInsights.setup('key'); appInsights.setAutoCollectExpressMiddleware(true); appInsights.start();

Method is added to the applicationinsights instance after requiring the middleware package, not exported directly.

ApplicationInsights

wrong

import { ApplicationInsights } from 'applicationinsights'

correct

const appInsights = require('applicationinsights');

ApplicationInsights SDK is CommonJS only; cannot be imported as named ES module.

Quickstart

Enables automatic tracking of Express middleware as dependencies in Azure Application Insights.

// run: npm install applicationinsights-express-middleware applicationinsights express

require('applicationinsights-express-middleware');
const appInsights = require('applicationinsights');
const express = require('express');

const app = express();

appInsights
  .setup(process.env.APPINSIGHTS_INSTRUMENTATIONKEY ?? '')
  .setAutoCollectExpressMiddleware(true)
  .start();

app.get('/', (req, res) => {
  res.send('Hello World');
});

app.listen(3000, () => console.log('Listening on 3000'));