Nodejs config api is package to make easier configuration nodejs configuration intergration with rabbitmq.

Getting started

Lets install nodco-rabbitmq with npm

npm install --save @musasutisna/nodco-rabbitmq

How to initialize

const nodcoRabbitmqConfig = require('@musasutisna/nodco-rabbitmq');

nodcoRabbitmqConfig(
  {
    host, // string, rabbitmq host
    port, // number, rabitmq port
    username, // string, rabbitmq user username
    password, // string, rabbitmq user password
    vhost, // string, rabbitmq virtual host
    queues, // array, list of queue will be declared
      [
        {
          name, // string, name of queue
          options // object, amqplib option for queue
        }
      ]
    exchanges // array, list of exchange list will be declared
      [
        {
          name, // string, name of exchange
          type, // string, typeof exchange
          options // object, amqplib option for exchange
        }
      ]
  }
)

| Method | Type | Description | |:--|:--|:--| | client | object | A list of RabbitMQ clients that are currently connected. | | channel| object | A list of RabbitMQ channels that are currently open. | | connect| async | Opens a connection to RabbitMQ. | | retries| async | Limits message retries using DLX (Dead Letter Exchange) properties. | | close | async | Closes all connections that have been established. |

connect Function

The connect function is an asynchronous function that establishes a connection to RabbitMQ. It ensures that the application is connected to the RabbitMQ server, allowing for communication and message processing.

Syntax

connect(key, cb);

Parameters

| Parameter | Type | Default | Description | |:--|:--|:--|:--| | key | object | N/A | The unique key in the configuration used during initialization to identify the connection configuration. | | cb | object | N/A | A callback function that is executed once the connection to RabbitMQ is successfully established. It receives the error (if any) and the connection object as parameters. |

Example

const configKey = 'myRabbitMQConfig';

connect(configKey, () => {
  console.log('Connected successfully.');
  // Further logic after successful connection can be added here.
});

Use Case

Establishing a connection to RabbitMQ: Use this function when you need to open a connection to the RabbitMQ server and perform operations like message publishing, subscribing to queues, or managing exchanges. The function ensures that the connection is properly initialized using the provided configuration.

retries Function

The retries function is an asynchronous function designed to handle message retry logic with a specified limit and optional republishing to another exchange if the limit is reached.

Syntax

retries(channel, msg, limit = 10, republish = null)

Parameters

| Parameter | Type | Default | Description | |:--|:--|:--|:--| | channel | object | N/A | An open RabbitMQ channel instance used to interact with the broker (e.g., for acknowledging or republishing messages). | | msg | object | N/A | The message object received from RabbitMQ, containing the message body, headers, and delivery metadata. | | limit | number | 10 | The maximum number of retry attempts allowed before acknowledging or republishing the message. | | republish | object | null | Optional. Specifies the configuration for republishing messages to another exchange. |

republish Object

If provided, the republish parameter should be an object with the following properties:

| Property | Type | Description | |:--|:--|:--| | exchange | string | The name of the target exchange to which the message will be republished. | | key | string | The routing key used to republish the message to the target exchange. |

Example

await retries(
  channel, 
  msg, 
  5, 
  { exchange: 'backup-exchange', key: 'retry-key' }
);

In this example:

• The message will be retried up to 5 times.
• If the retry limit is reached, the message will be republished to the backup-exchange using the routing key retry-key.
• If no limit is provided, the function will default to 10 retries. If republish is not specified, it will default to null.

Use Case

The retries function is ideal for scenarios where you need to limit the number of processing attempts for a message and handle messages that cannot be successfully processed by either:

• Acknowledging them after reaching the retry limit.
• Republishing them to a dead-letter exchange or a fallback mechanism for further investigation.