Check something on a remote site using AWS Lambda, Puppeteer, and SNS

futbin-checker.js

// See https://github.com/shelfio/chrome-aws-lambda-layer for more info
// on the layer needed to make chrome-aws-lambda work

const AWS = require('aws-sdk');
const chromium = require('chrome-aws-lambda');

exports.handler = async (event, context) => {  
    let sns = new AWS.SNS();
    
    let browser = await chromium.puppeteer.launch({
      args: chromium.args,
      defaultViewport: chromium.defaultViewport,
      executablePath: await chromium.executablePath,
      headless: chromium.headless,
      ignoreHTTPSErrors: true,
    });
    
    let page = await browser.newPage();
    await page.goto(process.env.REMOTE_URL);
    let top_of_range = await page.evaluate(() => {
      let range = document.getElementById('pr_ps').innerText;
      return range.match(/[\d\,]+/g)[1].replace(/,/g, '');
    });
    await browser.close();
    
    let message = `Top of range is now ${top_of_range}`;
    
    const promise = new Promise((resolve, reject) => {
      if (Number(top_of_range) == 150000) {
        resolve();
      }

      sns.publish({
        Message: message,
        TopicArn: process.env.SNS_ARN
      }, function(err, data) {
        if (err) {
          console.log(err.stack);
          reject();
        }
        resolve();
      });
    });
    
    return promise;
};