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Publish to a Queue via HTTP

Publish to a Queue directly via HTTP and Workers.

The following example shows you how to publish messages to a queue from any HTTP client, using a shared secret to securely authenticate the client.

This allows you to write to a Queue from any service or programming language that support HTTP, including Go, Rust, Python or even a Bash script.

Prerequisites

Configure your wrangler.toml file as follows:

name = "my-worker"


[[queues.producers]]
  queue = "my-queue"
  binding = "YOUR_QUEUE"

1. Create a shared secret

Before you deploy the Worker, you need to create a secret that you can use as a shared secret. A shared secret is a secret that both the client uses to authenticate and the server (your Worker) matches against for authentication.

To generate a cryptographically secure secret, you can use the openssl command-line tool and wrangler secret to create a hex-encoded string that can be used as the shared secret:

Terminal window
openssl rand -hex 32
# This will output a 65 character long hex string

Copy this string and paste it into the prompt for wrangler secret:

Terminal window
npx wrangler secret put QUEUE_AUTH_SECRET
✨ Success! Uploaded secret QUEUE_AUTH_SECRET

This secret will also need to be used by the client application writing to the queue: ensure you store it securely.

2. Create the Worker

The following Worker script:

  1. Authenticates the client using a shared secret.
  2. Validates that the payload uses JSON.
  3. Publishes the payload to the queue.
interface Env {
  YOUR_QUEUE: Queue;
  QUEUE_AUTH_SECRET: string;
}


export default {
  async fetch(req, env): Promise<Response> {
    // Authenticate that the client has the correct auth key
    if (env.QUEUE_AUTH_SECRET == "") {
      return Response.json(
        { err: "application not configured" },
        { status: 500 },
      );
    }


    // Return a HTTP 403 (Forbidden) if the auth key is invalid/incorrect/misconfigured
    let authToken = req.headers.get("Authorization") || "";
    let encoder = new TextEncoder();
    // Securely compare our secret with the auth token provided by the client
    try {
      if (
        !crypto.subtle.timingSafeEqual(
          encoder.encode(env.QUEUE_AUTH_SECRET),
          encoder.encode(authToken),
        )
      ) {
        return Response.json(
          { err: "invalid auth token provided" },
          { status: 403 },
        );
      }
    } catch (e) {
      return Response.json(
        { err: "invalid auth token provided" },
        { status: 403 },
      );
    }


    // Optional: 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: 500 });
    }


    // 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

3. Send a test message

To make sure you successfully authenticate and 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 -H "Authorization: pasteyourkeyhere" "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 403, this is because the Authorization header is invalid, or you did not configure a secret.
  • If you receive a HTTP 500, this is either because you did not correctly create a shared secret to your Worker, or you attempted to send an invalid message to your queue.

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

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