Functions you can follow

functions/checkout.ts

import { ferrule } from "@ferrule/sdk";

export default ferrule.fn("checkout", async (req, ctx) => {
  const { cart, email } = await req.json();
  const items = await ctx.db.carts.get(cart);   // span: CH5
  ctx.log("cart loaded", { items: items.length });

  const order = await ctx.queue.send("orders", { cart, email }, {
    idempotencyKey: req.headers.get("idempotency-key"),
    retries: 3,
  });
  return Response.json({ id: order.id, status: "created" }, { status: 201 });
});

functions/checkout.py

from ferrule import fn, Response

@fn("checkout")
async def checkout(req, ctx):
    body = await req.json()
    items = await ctx.db.carts.get(body["cart"])  # span: CH5
    ctx.log("cart loaded", items=len(items))

    order = await ctx.queue.send(
        "orders", body,
        idempotency_key=req.headers.get("idempotency-key"),
        retries=3,
    )
    return Response.json({"id": order.id, "status": "created"}, status=201)

functions/checkout.go

package functions

import "github.com/example/ferrule-go"

func Checkout(req *ferrule.Request, ctx *ferrule.Ctx) (*ferrule.Response, error) {
	var body struct{ Cart, Email string }
	if err := req.JSON(&body); err != nil {
		return nil, err
	}
	items, err := ctx.DB.Carts.Get(body.Cart) // span: CH5
	if err != nil {
		return nil, err
	}
	ctx.Log("cart loaded", "items", len(items))

	order, err := ctx.Queue.Send("orders", body, ferrule.Retries(3))
	if err != nil {
		return nil, err
	}
	return ferrule.JSON(201, map[string]string{"id": order.ID, "status": "created"}), nil
}

tty1

# deploy the folder, then call it over HTTP
npx ferrule deploy functions/

curl -X POST https://shop.example.com/api/checkout \
  -H "Authorization: Bearer $SHOP_KEY" \
  -H "Idempotency-Key: ck_7Q" \
  -d '{"cart":"c_8Q2","email":"[email protected]"}'

# print the trace of the last request
npx ferrule trace --last