Hetzner

Host your Durable Objects on Hetzner Cloud, and the control plane runs on Servers with a Volume each, behind a private Load Balancer and an HTTPS edge. Each node in a pool is a Server of its own. It’s where Part 4 of the tutorial runs the rooms.

src/cluster.ts

import * as RivetHetzner from "@alchemy.run/rivet/Hetzner";
import * as Layer from "effect/Layer";

export const Cluster = RivetHetzner.ServerControlPlane("Rivet");

export const Default = RivetHetzner.ServerPool("Default").pipe(Layer.provide(Cluster));

Install @alchemy.run/hetzner and finish Hetzner setup.

The control plane

You get one engine on a Server, with its data on a Volume, behind a Load Balancer on the private Network. A small edge Server runs Caddy in front of it and serves the engines over HTTPS at its own address under sslip.io, like https://203-0-113-7.sslip.io, with a certificate from Let’s Encrypt, so you need no domain. A firewall blocks every other connection to the engines.

src/cluster.ts

export const Cluster = RivetHetzner.ServerControlPlane("Rivet", {
  location: "fsn1",
  serverType: "cx33",
  diskSize: 40,
});

Run more engines

More engines share object storage, so objectStorage is required. Hetzner Object Storage works:

src/cluster.ts

export const Cluster = RivetHetzner.ServerControlPlane("Rivet", {
  instances: 3,
  objectStorage: {
    kind: "s3",
    bucket: "my-rivet-data",
    endpoint: "https://nbg1.your-objectstorage.com",
    region: "nbg1",
    accessKeyId: Config.String("HETZNER_S3_ACCESS_KEY_ID"),
    secretAccessKey: Config.Redacted("HETZNER_S3_SECRET_ACCESS_KEY"),
  },
});

Create the bucket and its keys in the Hetzner console first.

The pool

src/cluster.ts

export const Default = RivetHetzner.ServerPool("Default", { replicas: 2, serverType: "cx23" }).pipe(
  Layer.provide(Cluster),
);

Each node’s firewall only allows SSH, which Alchemy uses to deploy it.

Rivet Services

ServicesPool runs Rivet Services on a Server of its own, behind a firewall that drops every inbound connection:

src/cluster.ts

export const Services = RivetHetzner.ServicesPool("Services").pipe(Layer.provide(Cluster));

Call it from a Hetzner Service

src/api.ts

export const ApiServer = Hetzner.Server("ApiServer", {
  serverType: "cx23",
  image: "ubuntu-24.04",
  location: "nbg1",
});

export default class Api extends Hetzner.Service<Api>()(
  "Api",
  { server: ApiServer, main: import.meta.url },
  Effect.gen(function* () {
    const rooms = yield* Room;
    return {
      fetch: Effect.gen(function* () {
        const visitors = yield* rooms.getByName("lobby").join();
        return yield* HttpServerResponse.json({ visitors });
      }),
    };
  }),
) {}

Part 4 of the tutorial deploys this.

Every option, with its default, is in the reference: ServerControlPlane, ServerPool and ServicesPool.