Cloudflare Developers•2mo ago

How to access environment variables in Cloudflare Workers when using RPC binding

I'm working with two separate Cloudflare Workers, where Worker A calls a function in Worker B via a binding (RPC). Worker B requires an environment variable to send an email, and this variable should be scoped to Worker B itself, so it doesn't depend on Worker A's environment. Here's the relevant code for Worker B:

export class WorkerEmail extends WorkerEntrypoint {
  // Currently, entrypoints without a named handler are not supported

  async fetch(request: Request): Promise<Response> {
    const url = new URL(request.url);
    if (url.pathname === "/send" && request.method === "POST") {
      const { email, firstName }: { email: string; firstName: string } =
        await request.json();
      return this.send(email, firstName, this.env as Env); // Attempting to pass env here
    }
    return new Response(null, { status: 404 });
  }

  
  async send(email: string, firstName: string, env: Env): Promise<Response> {
    const resend = new Resend(env.RESEND_API); // env.RESEND_API should come from Worker B's environment
    
  }
}

export class WorkerEmail extends WorkerEntrypoint {
  // Currently, entrypoints without a named handler are not supported

  async fetch(request: Request): Promise<Response> {
    const url = new URL(request.url);
    if (url.pathname === "/send" && request.method === "POST") {
      const { email, firstName }: { email: string; firstName: string } =
        await request.json();
      return this.send(email, firstName, this.env as Env); // Attempting to pass env here
    }
    return new Response(null, { status: 404 });
  }

  
  async send(email: string, firstName: string, env: Env): Promise<Response> {
    const resend = new Resend(env.RESEND_API); // env.RESEND_API should come from Worker B's environment
    
  }
}

When I use HTTP with fetch in Worker A, it works fine:

await c.env.WORKER_EMAIL.fetch(
  new Request("https://worker-email/send", {
    method: "POST",
    headers: { "Content-Type": "application/json" },
    body: JSON.stringify({ email, firstName }),
  })
);

await c.env.WORKER_EMAIL.fetch(
  new Request("https://worker-email/send", {
    method: "POST",
    headers: { "Content-Type": "application/json" },
    body: JSON.stringify({ email, firstName }),
  })
);

However, if I want to call Worker B directly via an RPC-style binding (like await c.env.WORKER_EMAIL.send(email, firstName)), I run into issues with accessing the environment variable env.RESEND_API directly in Worker B. It seems the environment is not properly scoped when using RPC and it stays undefined Question: How can I pass the correct environment to Worker B's send function when using RPC? Or is there a better way to structure this to ensure Worker B can access its own environment variables independently of Worker A? What am I missing here? Any guidance would be greatly appreciated!

2 Replies

NleaOP•2mo ago

@Skye, thanks for pointing that out! While I used this.env within the fetch function to pass the env parameter to the send function, it didn’t occur to me that I don’t actually need the env parameter—I can simply declare it within the send function 🤦‍♀️ . I think I had a big mental block there. Thanks for helping me untangle it!

hkdobrev•2w ago

If anyone is stumbling upon this when using TypeScript, just make sure to define your Env interface and then extend WorkerEntrypoint<Env> this allows this.env to be visible by the ts compiler and to not cause any warnings in development. this exists in other examples, but not in the RPC ones.

Gaming

Programming

How to access environment variables in Cloudflare Workers when using RPC binding