Generate PDFs in Netlify Functions

// netlify/functions/invoice.mjs
export default async (req, context) => {
  const { invoiceId } = await req.json();
  const html = await buildInvoiceHtml(invoiceId);

  const res = await fetch("https://rendral.com/api/v1/pdf", {
    method: "POST",
    headers: {
      Authorization: "Bearer " + Netlify.env.get("RENDRAL_API_KEY"),
      "Content-Type": "application/json",
    },
    body: JSON.stringify({
      html,
      options: { format: "A4", pageNumbers: true },
    }),
  });

  if (!res.ok) {
    return new Response("Render failed", { status: 502 });
  }

  return new Response(res.body, {
    headers: {
      "Content-Type": "application/pdf",
      "Content-Disposition": 'inline; filename="invoice.pdf"',
    },
  });
};