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Publish to a Queue via Workers

Publish to a Queue directly from your Worker.

The following example shows you how to publish messages to a Queue from a Worker. The example uses a Worker that receives a JSON payload from the request body and writes it as-is to the Queue, but in a real application you might have more logic before you queue a message.

Prerequisites

Configure your Wrangler file as follows:

{
  "name": "my-worker",
  "queues": {
    "producers": [
      {
        "queue": "my-queue",
        "binding": "YOUR_QUEUE"
      }
    ]
  }
}

1. Create the Worker

The following Worker script:

  1. Validates that the request body is valid JSON.
  2. Publishes the payload to the queue.
interface Env {
  YOUR_QUEUE: Queue;
}


export default {
  async fetch(req, env): Promise<Response> {
    // Validate the payload is JSON
    // In a production application, we may more robustly validate the payload
    // against a schema using a library like 'zod'
    let messages;
    try {
      messages = await req.json();
    } catch (e) {
      // Return a HTTP 400 (Bad Request) if the payload isn't JSON
      return Response.json({ err: "payload not valid JSON" }, { status: 400 });
    }


    // Publish to the Queue
    try {
      await env.YOUR_QUEUE.send(messages);
    } catch (e: any) {
      console.log(`failed to send to the queue: ${e}`);
      // Return a HTTP 500 (Internal Error) if our publish operation fails
      return Response.json({ error: e.message }, { status: 500 });
    }


    // Return a HTTP 200 if the send succeeded!
    return Response.json({ success: true });
  },
} satisfies ExportedHandler<Env>;

To deploy this Worker:

Terminal window
npx wrangler deploy

2. Send a test message

To make sure you successfully write a message to your queue, use curl on the command line:

Terminal window
# Make sure to replace the placeholder with your shared secret
curl -XPOST "https://YOUR_WORKER.YOUR_ACCOUNT.workers.dev" --data '{"messages": [{"msg":"hello world"}]}'
{"success":true}

This will issue a HTTP POST request, and if successful, return a HTTP 200 with a success: true response body.

  • If you receive a HTTP 400, this is because you attempted to send malformed JSON to your queue.
  • If you receive a HTTP 500, this is because the message was not written to your Queue successfully.

You can use wrangler tail to debug the output of console.log.