How to run Puppeteer (Headless Chrome) using Google Firebase Cloud Functions

Jesus Manuel Olivas

June 04, 2019

After following a discussion at the GatsbyJS discord space about running puppeter using a cloud function. I decided to give it a try and in this post I will share my experience.

What is Puppeteer?

Puppeteer is a Node library which provides a high-level API to control Chrome or Chromium over the DevTools Protocol. Puppeteer runs headless by default.

Why Puppeteer?

This library comes with everything you need to:

Generate screenshots and PDFs of pages.
Crawl a SPA.
Pre-render content (i.e. "SSR" (Server-Side Rendering)).
Automate form submission, UI testing, keyboard input, etc.

For te purpose of tihs example we are going to take advantage of the screenshot generation.

Which Cloud Provider?

For the purpose of this example. I will be using a Cloud Function from Google Firebase service

Adding the puppeteer dependency

To use Puppeteer in your project using npm execute on your functions directory:

npm install --save puppeteer

The Firebase Cloud Function

The following example creates a new http function to handle the request using the <https://path-to-your-project.web.app>/screeshot url. This returns a screenshot of the provided url query parameter.

exports.screenshot = functions
  .runWith({
    timeoutSeconds: 120,
    memory: "2GB"
  })
  .https.onRequest((request, response) => {
    (async () => {
      const url = request.query.url;
      const width = parseInt(request.query.width) || 1024;
      const height = parseInt(request.query.height) || 768;
      const fullPage = request.query.full
        ? request.query.full === "true"
        : false;

      if (!url) {
        return response.send(`Invalid url: ${url}`);
      }

      const browser = await puppeteer.launch({
        args: ["--no-sandbox"]
      });
      const page = await browser.newPage();

      await page.goto(url, { waitUntil: "networkidle2" });

      if (!fullPage) {
        await page.setViewport({ width, height });
      }

      const screenshot = await page.screenshot({ fullPage });

      await browser.close();

      return response.type("image/png").send(screenshot);
    })();
  });

Note the runWith method is used in order to set timeout and memory allocation used on the cloud function execution.

How to use it?

Passing the url and using the default width and height values /screenshot?url=https://jmolivas.com/
Passing the url and width and height values /screenshot?url=https://jmolivas.com/&width=1200&height=1600
Forcing full page /screenshot?url=https://jmolivas.com/&full=true

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