Supabase Edge Functions

Generating PDFs from Supabase Edge Functions

Edge Functions give you 256 MB of memory, 2 seconds of CPU and a 20 MB bundle. Chromium is about 300 MB. That is the entire problem — and the reason the fix is not a smaller browser but moving the render off the function.

The limits you are working inside

Figures from Supabase's published Edge Function limits. Verify against their docs before designing around them.

Your three real options

Complete example: render, store, sign

The pattern most invoice and certificate flows want — the PDF lands in Storage and the caller gets a time-limited URL. Set the key with supabase secrets set RENDERFY_API_KEY=rfy_live_...

// supabase/functions/generate-invoice/index.ts
import { createClient } from "npm:@supabase/supabase-js@2";

const supabase = createClient(
  Deno.env.get("SUPABASE_URL")!,
  Deno.env.get("SUPABASE_SERVICE_ROLE_KEY")!,
);

Deno.serve(async (req) => {
  const { invoiceId } = await req.json();

  const { data: invoice, error } = await supabase
    .from("invoices")
    .select("*")
    .eq("id", invoiceId)
    .single();

  if (error) {
    return Response.json({ error: error.message }, { status: 404 });
  }

  // Awaiting this is I/O — it does not touch the 2s CPU budget.
  const render = await fetch("https://renderfy.io/api/v1/render", {
    method: "POST",
    headers: {
      Authorization: `Bearer ${Deno.env.get("RENDERFY_API_KEY")}`,
      "Content-Type": "application/json",
    },
    body: JSON.stringify({
      type: "html",
      content: invoiceHtml(invoice),
      options: { format: "pdf", dimensions: "a4" },
    }),
  });

  if (!render.ok) {
    return Response.json({ error: "Render failed" }, { status: 502 });
  }

  const pdf = await render.arrayBuffer();
  const path = `invoices/${invoice.id}.pdf`;

  const { error: uploadError } = await supabase.storage
    .from("documents")
    .upload(path, pdf, {
      contentType: "application/pdf",
      upsert: true,
    });

  if (uploadError) {
    return Response.json({ error: uploadError.message }, { status: 500 });
  }

  const { data: signed } = await supabase.storage
    .from("documents")
    .createSignedUrl(path, 60 * 60); // 1 hour

  return Response.json({ url: signed?.signedUrl });
});

Deploy with supabase functions deploy generate-invoice. The function bundle stays a few kilobytes, because nothing heavy ships with it.

Two things to get right

• →Use the service role key only inside the function. It bypasses row-level security. The client should receive the signed URL, never the key.
• →Make retries safe. If the caller retries after a network blip you do not want to be charged twice or write a second object. Send an Idempotency-Key derived from the invoice id, and keep upsert: true on the Storage write.