applicationinsights-express-middleware

Express Middleware tracking for Microsoft Application Insights SDK for Node.js.

Contents

• About
• Usage
  • Dependency Tracking Data
• Developing
  • Install
  • Build
  • Test
  • Lint
• Contributing
• Changelog

About

This repository provides Express Middleware tracking for the Application Insights SDK for Node.js by monkey patching Express and the Application Insights SDK.

Note: This package is currently a WIP and likely to have bugs - please raise issues for anything you find. Please don't use in Production!

Usage

Install this package using npm / yarn.

yarn add applicationinsights-express-middleware

In your application code, require this package before Express and Application Insights:

require("applicationinsights-express-middleware");

const appInsights = require("applicationinsights");
const express = require("express");

...

Or alternatively, use it instead of Application Insights:

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

...

You can enable the auto-collection of Express middleware data by calling setAutoCollectExpressMiddleware(true) while configuring Application Insights:

appInsights
  .setup("<INSTRUMENTATION_KEY>")
  .setAutoCollectExpressMiddleware(true) // Use with or without the other chained auto-collection configuration methods.
  .start();

The default for the Express middleware auto-collection is false, so not calling this method (and calling it with false) will result in the Express middleware not being instrumented.

If you set the value to true, then the once the Application Insights start() method is invoked, the package will then automatically invoke trackDependency() whenever Express middleware is executed.

Please note that the package currently does not support the dispose() method and therefore will not stop instrumenting Express until application restart.

Dependency Tracking Data

The Express middleware data that is sent to Application Insights is of the following form:

{
  "dependencyTypeName": "Express Middleware",
  "target": "/",
  "name": "GET / myMiddleware",
  "data": "",
  "duration": 10,
  "resultCode": 0,
  "success": true,
  "time": "2020-05-02T00:00:16.285Z"
}

Key	Values
dependencyTypeName	One of: "Express Middleware", or "Express Param Middleware", or "Express Error Middleware".
target	The Express path associated with the middleware being executed.
name	The request method and Express path followed by the middleware function's name, or "<anonymous>" if the middleware function does not have a name. E.g. "GET / myMiddleware", or "POST /users/:userId <anonymous>".
data	The error passed to the middleware function's next() method, or an empty string if no error was passed.
duration	The duration of time taken to execute the middleware function in milliseconds.
resultCode	1 if the middleware function called the next() method with an error, otherwise 0.
success	false if the middleware function called the next() method with an error, otherwise true.
time	The datetime when the middleware function was invoked.

Developing

Install

yarn install --frozen-lockfile

Build

yarn build

Test

yarn test

Lint

yarn lint

Contributing

Please check out the CONTRIBUTING docs.

Changelog

Please check out the CHANGELOG docs.