Event Emitter based node library that emits process metrics (uptime, memory, cpu) at given intervals
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README.md

metrica

npm version CircleCI codecov.io JavaScript Style Guide

Event Emitter based node library that emits process metrics (uptime, memory, cpu) at given intervals

Install & quick usage

Requirements: this library is written for Node.js >= 6.0

As usual, this happens through NPM:

npm install --save metrica

Then, in your code:

const m = require('metrica')()
// metrics is an event emitter

m.on('tick', (data) => console.log(data))
// tick happens (by default) every minute and data will look like:
// {
//   cpu: {
//     user: 129255,
//     system: 25515
//   },
//   memory: {
//     rss: 21843968,
//     heapTotal: 8208384,
//     heapUsed: 5394352,
//     external: 8628
//   },
//   uptime: 44.858
// }

🤔 Rationale

When running your Node.js app in production you might be interested in gathering metrics about the running process. Perhaps, you want to log this information or send it to a centralized metrics system.

This library gives you an easy way to collect process metric continuously and offers a convenient event based interface so that you can easily attach your custom logic to handle the new metrics.

Options

When instantiating a new process metrics you can specify some options:

interval: 60000, autoStart: true

  • interval (default 60000) - Allows you to specify how often the metrics are collected. This can be a number (milliseconds) or a string expression as supported by the ms module
  • autoStart (default true) - Will automatically start the collection of metrics at given intervals. If set to false you should start the collection with the .start() method

Methods

A process metrics instance will expose few methods:

  • .start() - Will start the automatic collection of metrics (which will trigger tick events at given intervals)
  • .stop() - Will stop the automatic collection of metrics
  • .getMetrics() - Will get and return the current metrics. It's not going to trigger a tick event.

Events

A process metrics instance is an event emitter and will emit the following events:

  • tick - triggered continuously at the given interval time. It will contain as a payload the current metrics object.

Complete example

This example will collect and log metrics for 5 seconds and then stop the collection:

const metrica = require('metrica')
const m = metrica({ interval: '1s', autoStart: false })
m.on('tick', (metrics) => console.log('Tick:', metrics))
setTimeout(() => m.stop(), 5000)
m.start()

👯‍ Contributing

Everyone is very welcome to contribute to this project. You can contribute just by submitting bugs or suggesting improvements by opening an issue on GitHub.

🤦‍ License

Licensed under MIT License. © Luciano Mammino.