2 replies

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)

await c.env.WORKER_EMAIL.send(email, firstName)

), I run into issues with accessing the environment variable

env.RESEND_API

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!

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

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)

await c.env.WORKER_EMAIL.send(email, firstName)

), I run into issues with accessing the environment variable

env.RESEND_API

env.RESEND_API

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

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

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