Part 2: Configure the Service

In Part 1 you deployed a Service on its own fly.dev hostname. Now you will pin where it runs and which port it listens on, add a health route, and ship a change.

Pin a region

Fly Machines live in a region. The default is iad (Ashburn). Set it explicitly so the Volume you add in Part 3 can match:

export default class Api extends Fly.Service<Api>()(
  "Api",
  { main: import.meta.url },
  { main: import.meta.url, region: "iad" },

Changing region moves the Machine

A new Machine is created in the new region and the old one is deleted; the hostname stays the same. Regions lists the codes.

Set the port

Give the Service an explicit port so the Fly proxy knows where to forward:

export default class Api extends Fly.Service<Api>()(
  "Api",
  { main: import.meta.url, region: "iad" },
  { main: import.meta.url, region: "iad", port: 3000 },

The port is written to the process environment as PORT and used as the Machine’s internal_port. By default Alchemy publishes HTTP 80 and HTTPS 443 on the Fly proxy in front of it.

Add a health route

Add /health so you (and later, Fly checks) can probe the process:

src/api.ts

import { HttpServerRequest } from "effect/http/HttpServerRequest";
// ...
    return {
      fetch: Effect.succeed(HttpServerResponse.text("Hello from Fly!")),
      fetch: Effect.gen(function* () {
        const request = yield* HttpServerRequest;
        const url = new URL(request.url, "http://service");
        if (url.pathname === "/health") {
          return HttpServerResponse.json({ ok: true });
        }
        return HttpServerResponse.text("Hello from Fly!");
      }),
    };

Deploy

bun

bun alchemy deploy

npm

npm run alchemy deploy

pnpm

pnpm alchemy deploy

yarn

yarn alchemy deploy

Plan: 1 to update

~ Api (Fly.Service)

Proceed?
◉ Yes ○ No
✓ Api (Fly.Service) updated
{
  appName: "myapp-api-dev-a1b2c3d4",
  url: "https://myapp-api-dev-a1b2c3d4.fly.dev",
}

iad and port 3000 match the defaults from Part 1, so the Machine stays where it is. The new route changes the bundle hash, so Alchemy builds a new image and updates the Machine in place. The App and its URL stay the same.

Try it out

curl https://myapp-api-dev-a1b2c3d4.fly.dev/health
# → {"ok":true}

Ship a change

Edit the greeting in src/api.ts and deploy again:

Plan: 1 to update

~ Api (Fly.Service)

Proceed?
◉ Yes ○ No
✓ Api (Fly.Service) updated

Alchemy hashes the bundle: if your code didn’t change, the Service is a no-op; if it did, a new image is built, pushed, and the Machine updated in place.

Recap

You now have:

• An HTTP Service running as a Fly Machine in iad on port 3000
• A /health route on its public https://{appName}.fly.dev URL
• A code-hash-based update loop — edit, deploy, new image

In Part 3, you’ll attach a Volume and persist data across deploys.