Lighthouse Lambda Layer

A Lambda layer with all the required dependencies to run Google Lighthouse.

Prerequisites

Nodejs (at least version 10)

Yarn

Amazon AWS account and awscli installed and configured: https://aws.amazon.com/getting-started/

Serverless CLI

Setup

yarn

Deploy

yarn deploy

Usage

In your serverless.yml:

functions:
  functionThatUsesLighthouse:
    layers:
      - layerArn # You'll have this after you run the deploy command

In you Lambda function:

const lighthouse = require('lighthouse');
const log = require('lighthouse-logger');
const chromeLauncher = require('chrome-launcher');

let chromePath = undefined;

// this lets us support invoke local
if (!process.env.IS_LOCAL) {
  chromePath = '/opt/bin/chromium';

  // https://github.com/alixaxel/chrome-aws-lambda/blob/3779715fdc197a245af662725977133b2d676bf9/source/index.js#L6
  // required for node10 support - makes sure fonts and shared libraries are loaded correctly
  if (process.env.FONTCONFIG_PATH === undefined) {
    process.env.FONTCONFIG_PATH = '/opt/lib';
  }

  if (
    process.env.LD_LIBRARY_PATH &&
    process.env.LD_LIBRARY_PATH.startsWith('/opt/lib:') !== true
  ) {
    process.env.LD_LIBRARY_PATH = [
      ...new Set(['/opt/lib', ...process.env.LD_LIBRARY_PATH.split(':')]),
    ].join(':');
  }
}

const chromeFlags = [
  '--headless',
  '--disable-dev-shm-usage',
  '--disable-gpu',
  '--no-zygote',
  '--no-sandbox',
  '--single-process',
  '--hide-scrollbars',
];

// utility function to run lighthouse
const runLighthouse = async url => {
  let chrome = null;
  try {
    chrome = await chromeLauncher.launch({ chromeFlags, chromePath });

    const options = {
      port: chrome.port,
      logLevel: 'info',
    };

    log.setLevel(options.logLevel);

    const results = await lighthouse(url, options);
    return results;
  } finally {
    if (chrome) {
      await chrome.kill();
    }
  }
};

// do something with runLighthouse