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    0.1.7 • Public • Published

    Express Loadmill

    Users of Loadmill can use this express middleware for:

    1. Quick and easy domain verification.
    2. Enabling CORS strictly from in order to perform crowdsourced load tests.
    3. Sample performance metrics of the Node process to be viewed alongside client-side metrics during a load test.


    Using npm:

    npm install express-loadmill --save

    Using yarn:

    yarn add express-loadmill


    Use loadmill middleware before everything else (that should be exposed to testing):

    var app = require('express')();
    var Loadmill = require('express-loadmill');
    app.use(Loadmill({verifyToken: process.env.LOADMILL_VERIFY_TOKEN}));

    The above code enables both CORS and domain verification. You may optionally disable CORS by setting the enableCors option to false, e.g.

    app.use(Loadmill({enableCors: false, verifyToken: process.env.LOADMILL_VERIFY_TOKEN}));

    Note however that you will not be able to perform high-volume load tests with loadmill without enabling CORS.

    Domain verification will only be enabled if you supply a verification token, thus the following code will only enable CORS:



    To enable cookies being sent to and from the server (by setting Access-Control-Allow-Credentials response header), set the enableCookies option to true, e.g.

    app.use(Loadmill({enableCookies: true, verifyToken: process.env.LOADMILL_VERIFY_TOKEN}));

    Note that you will also need to enable cookies for your test in the Advanced Settings section of your test configuration.


    By enabling performance monitoring, samples of CPU and memory usage of the Node process will be sent to Loadmill (only during load testing) and will be displayed alongside client-side metrics in your performance metrics charts.


    The monitoring module is an optional dependency, therefore you must install it. Before installing, make sure you are using Node version v6.1.0 or higher.

    Using npm:

    npm install express-loadmill loadmill-monitor --save

    Using yarn:

    yarn add express-loadmill loadmill-monitor

    To enable monitoring, you need to configure monitor options with a personal API token (note this is not the same as verifyToken):

        verifyToken: process.env.LOADMILL_VERIFY_TOKEN,
        monitor: {
            // Required:
            apiToken: process.env.LOADMILL_API_TOKEN,
            // Default is TRUE:
            enabled: process.env.ENABLE_LOADMILL_MONITORING

    Learn More


    npm i express-loadmill

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    • itaysabato
    • yigall