warmup

warmup

Simple module to warmup a server application (such as an Express app) by hitting server URLs and performing various tasks. This module also allows a worker to be warmed up before it is added to a cluster.

Installation

npm install warmup

Usage

var warmup = require('warmup');
warmup(app, tasks, callback);
warmup(app, tasks, options, callback);

Simple example of warming up an Express server application:

var warmup = require('warmup');
var express = require('express');

var app = express();

// ...

warmup(
    app,
    [
        '/foo', // A URL to hit to warmup the server
        '/bar', // A URL to hit to warmup the server
        {
            path: '/baz', // Required
            headers: {
                'User-Agent': 'xxx'
            }
        },
        function myFunc(callback) { // A custom warmup task
            var port = this.port; // The warmup port is there if you need it
            callback();
        },
        {
            name: 'My long task', // You can give a task a name for debugging purposes
            func: function(callback) {
                setTimeout(function() {
                    callback();
                }, 1200);
            },
            timeout: 2000 // Override the default task timeout
        }
    ],
    {
        timeout: 1000 // Set a default task timeout
    }
    function(err) {
        if (err) {
            // handle error
        }
        app.listen(8080);
    });

Passing the warmup tasks information:

• string: as a string that contains the path of the url to make a GET request to during warmup, e.g. '/foo'
• object: as an object if you want to pass additional properties like headers to the request object. Be sure to pass a path property at the bare minimum when passing the request information in this case

The following options are supported:

• timeout - Timeout for each task (defaults to 10s)
• warmupPort - The warmup port to use (defaults to a random port in the range of [10,000-50,000])

The warmup module works by starting the app on a random HTTP port. This allows the application to be started without accepting traffic.

NOTES:

• All of the tasks are executed in parallel
• The default timeout is 10s