PDFCraft
AWS Lambda

PDF generation in AWS Lambda

The usual approach — packaging chrome-aws-lambda — is a 50 MB layer, a cold start measured in seconds, and a Chromium build you now own the patching of. Calling an API is a few kilobytes of code and no layer at all.

The code

// handler.mjs — API Gateway proxy integration
export const handler = async (event) => {
  const { html } = JSON.parse(event.body ?? '{}');

  const upstream = await fetch('https://api.pdfcraft.dev/v1/render', {
    method: 'POST',
    headers: {
      authorization: `Bearer ${process.env.PDFCRAFT_API_KEY}`,
      'content-type': 'application/json',
    },
    body: JSON.stringify({ html, options: { printBackground: true } }),
  });

  if (!upstream.ok) {
    const { error } = await upstream.json();
    return { statusCode: upstream.status, body: JSON.stringify({ error }) };
  }

  const pdf = Buffer.from(await upstream.arrayBuffer());

  return {
    statusCode: 200,
    headers: { 'content-type': 'application/pdf' },
    // API Gateway requires base64 for binary, and isBase64Encoded is what
    // tells it to decode again on the way out.
    body: pdf.toString('base64'),
    isBase64Encoded: true,
  };
};

What to watch for

Why not run the browser yourself

You can. Puppeteer and Playwright both work, and for a script you run by hand they are the right answer. The cost arrives at the point it becomes a service someone depends on: one long-lived browser per process rather than one per request, a semaphore so four renders do not become forty, a hard timeout that force-closes a hung page before it holds a slot forever, a scheduled restart because Chromium leaks, and a Chromium version you are now responsible for patching.

None of that is hard. All of it is work that has nothing to do with your product, and it fails under concurrency rather than in testing — which is the worst time to discover it.

Other frameworks

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