@kikobeats/cold-start NPM

cold-start

Last version

Create lazy singleton functions with cold-start capabilities.

Why

A cold start is the first time your code has been executed in a while (5–25minutes).

This concept has been using for some infrastructure providers, such as:

AWS Lambda shutting down λ functions after an inactivity time.
Heroku Dynos sleeping instances after 30 minutes no web traffic activity.

This library brings you this concept to be applied to any piece of software, like:

Keep up a pool of servers where actually just a few of them are actively used.
Keep expensive process running that most of the time it isn't being used.
Wrap some sensible pieces of code that need to be restarted after a while.

The mission of the library is to keep on sync machine resources with real usage.

It's specially useful when you want to shutdown a long-time process that actually is not being used, cutting down infrastructure costs.

Install

$ npm install @kikobeats/cold-start --save

Usage

const coldStart = require('@kikobeats/cold-start')()
const createBrowserless = require('browserless')
const ms = require('ms')

const getBrowserless = coldStart({
  // every cold start function need to have an unique name
  name: 'browserless',
  // setup lazy intialization, it should be return something to be use into succesive calls
  start: createBrowserless,
  // setup teardown, if it's necessary
  stop: browserless => browserless.destroy(),
  // how much idle time to consider the function can be stopped.
  duration: ms('5m')
})

;(async () => {
  // first call will initialize the cold start function
  await getBrowserless()

  // succesive calls will reuse the instance
  await getBrowserless()

  // If the cold start function is not being called in a time window of 5m,
  // the cold start function will be destroyed.
  // The first call after that will allocate it again
  await getBrowserless()
})()