Node-RED AMQP Ack/Prefetch Nodes

1.1.2 · deprecated · verified Wed Apr 22

The `node-red-contrib-amqp-ack` package provides Node-RED users with robust input and output nodes for interacting with AMQP message brokers like RabbitMQ. Its core functionality includes subscribing to (input) and publishing to (output) AMQP exchanges or queues, with explicit support for message acknowledgment and prefetch count control, ensuring more reliable message processing within Node-RED flows. The package, currently at stable version 1.1.2, has a slow release cadence for new features, with the last significant update dating back four years. A key differentiator is its focus on reliable message delivery through configurable ack and prefetch mechanisms, which are crucial for preventing message loss or excessive load on Node-RED instances. It bundles the `amqp-ts` library for underlying AMQP connectivity, which itself is built upon `amqplib`. However, the `amqp-ts` dependency is largely unmaintained, presenting significant compatibility issues with modern Node.js versions.

Common errors

```
Failed to load flow: Error: Cannot find module 'amqplib/lib/connection'.
```
cause The underlying `amqp-ts` library uses an old version of `amqplib` which is incompatible with newer Node.js versions or has module resolution issues in certain environments.

fix Upgrade your Node-RED instance to use a different AMQP package like `@meowwolf/node-red-contrib-amqp` which supports modern Node.js. If you must use this package, downgrade your Node.js runtime to version 8 or older (not recommended).
```
Error: read ECONNRESET / Connection closed. No error event. / Amqp rabbit disconnected issue.
```
cause The connection to the AMQP broker (e.g., RabbitMQ) was unexpectedly closed, often due to network instability, broker restart, or incorrect broker configuration.

fix Verify network connectivity between Node-RED and the AMQP broker. Check RabbitMQ server logs for client disconnect reasons. Ensure the AMQP server configuration node has correct hostname, port, and vhost settings. While the node attempts reconnection, persistent issues require external resolution.
```
Messages are received by the 'amqp in' node but disappear without being processed by subsequent nodes, or are re-delivered repeatedly.
```
cause The 'amqp in' node is configured with 'noAck' unchecked, but no 'amqp ack' node is present in the flow to acknowledge messages after processing, leading to the broker re-queueing them.

fix Ensure that every 'amqp in' node configured for explicit acknowledgment (`noAck` unchecked) has a corresponding 'amqp ack' node in its processing path to confirm message consumption. Place the 'amqp ack' node after all processing steps have successfully completed.

Warnings

breaking The underlying `amqp-ts` library is unmaintained and is anchored to `amqplib@0.4.2`, which only supports Node.js versions up to 8. This package is incompatible with modern Node.js runtimes (Node.js 10+).
Fix: It is strongly recommended to migrate to an alternative Node-RED AMQP package, such as `@meowwolf/node-red-contrib-amqp`, for compatibility with current Node.js versions. If migration is not an option, ensure your Node-RED instance runs on Node.js 8 or older, which is not recommended for security or performance.
deprecated This package is explicitly recommended to be replaced by alternative AMQP Node-RED contributions for environments using modern Node.js versions due to its core dependency's outdated status.
Fix: Consider uninstalling this package and installing `@meowwolf/node-red-contrib-amqp` via the Node-RED Palette Manager or npm: `npm install @meowwolf/node-red-contrib-amqp`.
gotcha Entering invalid credentials (username/password) in the AMQP configuration node can lead to Node-RED malfunctioning or becoming unresponsive, as the connection attempts might consume excessive resources.
Fix: Always double-check AMQP server credentials. Monitor Node-RED logs for connection errors. Ensure the RabbitMQ server is accessible and configured correctly.
gotcha When `noAck` is unchecked on the 'amqp in' node, messages are not automatically acknowledged. Failure to use an 'amqp ack' node downstream will leave messages unacknowledged in the queue, leading to redelivery upon connection loss or message processing timeout.
Fix: For reliable processing, always follow an 'amqp in' node with `noAck` unchecked by an 'amqp ack' node once message processing is complete. Implement error handling to ensure `nack` or `reject` is used for failed messages.

Install

npm install node-red-contrib-amqp-ack npm
yarn add node-red-contrib-amqp-ack yarn
pnpm add node-red-contrib-amqp-ack pnpm

Imports

Node-RED Node Registration
wrong:
```
import { AmqpInNode } from 'node-red-contrib-amqp-ack';
```
correct:
```
RED.nodes.registerType('amqp in', AmqpInNode);
RED.nodes.registerType('amqp out', AmqpOutNode);
RED.nodes.registerType('amqp ack', AmqpAckNode);
RED.nodes.registerType('amqp-server', AmqpServerConfigNode);
```
These are internal Node-RED registrations, typically found within the node's `.js` definition files. End-users interact with nodes by dragging them from the Node-RED editor palette. Direct ESM/CJS imports in user-land JavaScript are not how these Node-RED contrib nodes are typically consumed.

Loading Node Definitions (Internal Node-RED)

wrong:

import AmqpInNode from 'node-red-contrib-amqp-ack/nodes/amqp-in';

correct:

const AmqpInNode = require('./nodes/amqp-in.js');
const AmqpOutNode = require('./nodes/amqp-out.js');
const AmqpAckNode = require('./nodes/amqp-ack.js');
const AmqpServerConfigNode = require('./nodes/amqp-server.js');

This CommonJS `require` pattern is how Node-RED's runtime loads individual node definition files, typically from within the package's directory. ESM imports are not supported for these internal Node-RED node files.

Quickstart

This Node-RED flow demonstrates basic AMQP publish/subscribe with manual acknowledgment and prefetch. It includes an AMQP input node configured with acknowledgment, a debug node to display messages, and an AMQP ack node to manually acknowledge the message after processing. An inject node triggers an AMQP output node to publish messages to a specified exchange. A shared 'amqp-server' configuration node manages the connection to the RabbitMQ broker.

[{"id":"d16f7e8a.401828","type":"tab","label":"AMQP Ack/Prefetch Example","disabled":false,"info":"Example flow demonstrating AMQP input with acknowledgment and output."},{"id":"28b1e42a.5b512","type":"amqp in","z":"d16f7e8a.401828","name":"Listen to Queue (Ack)","server":"80c32d43.6826c8","exchange":"my-exchange","queue":"my-queue","exchangeType":"topic","routingKey":"#","noAck":false,"prefetch":1,"x":160,"y":120,"wires":[["71a7d6e6.2e47e8","65c3e7b.6f23e48"]]},{"id":"71a7d6e6.2e47e8","type":"debug","z":"d16f7e8a.401828","name":"Received Message","topic":"","property":"payload","x":390,"y":120,"wires":[]},{"id":"65c3e7b.6f23e48","type":"amqp ack","z":"d16f7e8a.401828","name":"Acknowledge Message","server":"80c32d43.6826c8","x":390,"y":180,"wires":[]},{"id":"ae7d5c7b.8f3b28","type":"inject","z":"d16f7e8a.401828","name":"","props":[{"p":"payload"},{"p":"topic","vt":"str"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"my.key","payload":"Hello AMQP","payloadType":"str","x":140,"y":300,"wires":[["69f41b9.5a52868"]]},{"id":"69f41b9.5a52868","type":"amqp out","z":"d16f7e8a.401828","name":"Publish to Exchange","server":"80c32d43.6826c8","exchange":"my-exchange","exchangeType":"topic","routingKey":"my.key","x":390,"y":300,"wires":[]},{"id":"80c32d43.6826c8","type":"amqp-server","name":"RabbitMQ Local","host":"localhost","port":"5672","vhost":"/","clientid":"node-red","heartbeat":"60","topology":"[]","tls":""}]

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