Hold your horses.

Enforce a budget on any cloud resource. One atomic operation that answers yes or no. No setup, no migration, no suprise bills.

A recursive function with a missing break statement can do 116 billion database reads before lunch. Someone needs to hold their horses.

// 50,000 text messages a month, and not one more.
const sms = hh.group("sms")
  .budget("messages", { limit: 50_000, renewal: renewal.monthly() });

// Sending to 200 people. Can we afford it?
const result = await sms
  .draw("messages", 200)
  .charge();

Declare your budgets

Limits travel inline with every draw, so there is no setup call and no migration. Change a constant, deploy, done.

import { HorseHolderClient, renewal } from "@horse-holder/client";

const hh = new HorseHolderClient({
  apiKey: process.env.HORSEHOLDER_API_KEY,
});

const storage = hh.group("r2-storage")
  .budget("put-ops", {
    limit: 1_000_000,
    warnings: [0.8],
    renewal: renewal.monthly({ timezone: "America/Chicago" }),
  })
  .budget("egress-bytes", {
    limit: 50_000_000_000,
    renewal: renewal.monthly(),
  });

Ask before you spend

Budgets in a group are drawn together or not at all. A refusal is a returned value, not a thrown error.

const result = await storage
  .draw("put-ops", 1)
  .draw("egress-bytes", object.size)
  .idempotent(uploadId)
  .charge();

if (!result.ok) {
  return tooExpensive({ retryAfter: result.retryAfter });
}

await bucket.put(key, object);

Or settle up afterwards

Hold an estimate, then commit what it actually cost. Crash instead, and the hold expires on its own.

const email = hh.group("transactional-email")
  .budget("sends", { limit: 200_000, renewal: renewal.monthly() });

// Hold the whole recipient list, then correct it to what actually went out.
const lease = await email
  .draw("sends", recipients.length)
  .idempotent(campaignId)
  .reserve({ ttlSeconds: 60 });

if (lease.ok) {
  const sent = await deliverCampaign(recipients);
  await lease.commit({ "sends": sent.length });
}

Install

The client is on npm as @horse-holder/client. Zero dependencies, and baseUrl defaults here, so an API key is all it needs.

npm install @horse-holder/client