HTTP

Worker A that declares a Service binding to Worker B can forward a Request object to Worker B, by calling the fetch() method that is exposed on the binding object.

For example, consider the following Worker that implements a fetch() handler:

wrangler.jsonc

{
  "name": "worker_b",
  "main": "./src/workerB.js"
}

wrangler.toml

name = "worker_b"
main = "./src/workerB.js"

export default {
  async fetch(request, env, ctx) {
    return new Response("Hello World!");
  }
}

The following Worker declares a binding to the Worker above:

wrangler.jsonc

{
  "name": "worker_a",
  "main": "./src/workerA.js",
  "services": [
    {
      "binding": "WORKER_B",
      "service": "worker_b"
    }
  ]
}

wrangler.toml

name = "worker_a"
main = "./src/workerA.js"
services = [
  { binding = "WORKER_B", service = "worker_b" }
]

And then can forward a request to it:

export default {
  async fetch(request, env) {
    return await env.WORKER_B.fetch(request);
  },
};

Note

If you construct a new request manually, rather than forwarding an existing one, ensure that you provide a valid and fully-qualified URL with a hostname. For example:

export default {
  async fetch(request, env) {
    // provide a valid URL
    let newRequest = new Request("https://valid-url.com", { method: "GET" });
    let response = await env.WORKER_B.fetch(newRequest);
    return response;
  }
};