WorkerEntrypoint

Source: src/Cloudflare/Workers/WorkerEntrypoint.ts

Bind a specific WorkerEntrypoint class exported by another Worker.

Binding a Worker directly in env (env: { TARGET: worker }) targets its default entrypoint. A Worker that exposes additional WorkerEntrypoint classes — workerd treats every named class export of an entry module as an entrypoint — is bound with WorkerEntrypoint, which selects the class by name and can deliver ctx.props to it.

Defining the Target Entrypoint

Export a class extending Cloudflare’s native WorkerEntrypoint from the target Worker’s module. This Api class defines the RPC methods that callers can invoke through a named service binding.

target/src/worker.ts

import { WorkerEntrypoint } from "cloudflare:workers";

export class Api extends WorkerEntrypoint {
  async greet(name: string): Promise<string> {
    return `hello ${name}`;
  }
}

export default {
  async fetch() {
    return new Response("ok");
  },
};

Binding a Named Entrypoint

Import the exported Api class as a type and select its named export with "Api". Pass its instance type (Api, not typeof Api) to get Cloudflare’s native Service<Api> RPC client. Without a type argument, the binding is a bare Fetcher; the entrypoint name alone cannot identify the class’s type.

alchemy.run.ts

import * as Cloudflare from "alchemy/Cloudflare";
import type { Api } from "./target/src/worker.ts";

const target = yield* Cloudflare.Worker("Target", {
  main: "./target/src/worker.ts",
});

const caller = yield* Cloudflare.Worker("Caller", {
  main: "./caller/src/worker.ts",
  env: {
    API: Cloudflare.WorkerEntrypoint<Api>(target, "Api"),
  },
});

caller/src/worker.ts

import type { CallerEnv } from "../../alchemy.run.ts";

export default {
  async fetch(request: Request, env: CallerEnv) {
    return new Response(await env.API.greet("alice"));
  },
};

Delivering ctx.props

The options form attaches properties the target reads from this.ctx.props — workerd’s per-binding configuration channel. Output values resolve at deploy time.

env: {
  VENDOR: Cloudflare.WorkerEntrypoint(vendorWorker, {
    entrypoint: "Vendor",
    props: { baseUrl: site.url },
  }),
}