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Publish to a Queue via Workers

Publish to a Queue directly from your Worker.

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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:

{
	"$schema": "./node_modules/wrangler/config-schema.json",
	"name": "my-worker",
	"queues": {
		"producers": [
			{
				"queue": "my-queue",
				"binding": "YOUR_QUEUE"
			}
		]
	}
}
"$schema" = "./node_modules/wrangler/config-schema.json"
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, ctx): 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 {
			// Return a HTTP 400 (Bad Request) if the payload isn't JSON
			return Response.json({ error: "payload not valid JSON" }, { status: 400 });
		}

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

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

To deploy this Worker:

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:

# 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.