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Social Cards as a Service

I love the idea of programmatically generated images. That power is close at hand these days for us front-end developers, thanks to the concept of headless browsers. Take Puppeteer, the library for controlling headless Chrome. Generating images from URLs is their default use case:

const puppeteer = require('puppeteer');

(async () => {
  const browser = await puppeteer.launch();
  const page = await browser.newPage();
  await page.goto('https://example.com');
  await page.screenshot({path: 'example.png'});

  await browser.close();
})();

That ought to get the ol' mind grape going. What if we had URLs on our site that — with the power of our HTML and CSS skills — created perfect little designs for sharing using dynamic data... then turned them into images and used them for our meta tags?

The first I saw of this idea was Drew McLellan's Dynamic Social Sharing Images. Drew wrote a script to fire up Puppeteer and get the job done.

Since the design part is entirely an HTML/CSS adventure, I'm sure you could imagine a setup where the URL passed in parameters that did things like set copy and typography, colors, sizes, etc. Zeit built exactly that!

The URL is like this:

https://og-image.now.sh/I%20am%20Chris%20and%20I%20am%20**cool**%20la%20tee%20ding%20dong%20da..png?theme=light&md=1&fontSize=100px&images=https%3A%2F%2Fassets.zeit.co%2Fimage%2Fupload%2Ffront%2Fassets%2Fdesign%2Fhyper-color-logo.svg

Kind of amazing that you can spin up an entire browser in a cloud function! Netlify also offers cloud functions, and when I mentioned this to Phil Hawksworth, he told me he was already doing this for his blog!

So on a blog post like this one, an image like this is automatically generated:

Which is inserted as meta:

<meta property="og:image" content="https://www.hawksworx.com/card-image/-blog-find-that-at-card.png">

I dug through Phil's repos, naturally, and found his little machine for doing it.

I'm madly envious of all this and need to get one set up for myself.

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