MqttOptions

Kind: Interface

Source: packages/microservices/interfaces/microservice-configuration.interface.ts

Part of: Microservices

MqttOptions configures a NestJS microservice that communicates through the MQTT transport. It combines standard MQTT client settings with Nest-specific serialization, deserialization, subscription, and MQTT v5 user-property options.

Properties

Diagram

mermaid
graph LR
  A[Microservice Configuration] --> B[MqttOptions]
  B --> C[transport: Transport.MQTT]
  B --> D[options]
  D --> E[MqttClientOptions]
  D --> F[url]
  D --> G[serializer / deserializer]
  D --> H[subscribeOptions]
  D --> I[userProperties]
  H --> J[qos, nl, rap, rh]
  B --> K[MQTT Broker]

Usage

ts
import { Transport } from '@nestjs/microservices';
import type { MqttOptions } from '@nestjs/microservices';

const mqttConfig: MqttOptions = {
  transport: Transport.MQTT,
  options: {
    url: 'mqtt://localhost:1883',
    clientId: 'orders-service',
    clean: true,

    subscribeOptions: {
      qos: 1,
      nl: false,
      rap: true,
      rh: 0,
    },

    userProperties: {
      service: 'orders',
      environment: 'production',
    },
  },
};

// Example integration:
// NestFactory.createMicroservice(AppModule, mqttConfig);

AI Coding Instructions

• Always set transport to Transport.MQTT; this interface is specifically for MQTT microservice configurations.
• Use options.url for the broker connection string, or provide equivalent host, port, and protocol settings supported by MqttClientOptions.
• Configure serializer and deserializer together when using a custom message format so outgoing and incoming payloads remain compatible.
• Set subscribeOptions.qos intentionally based on delivery guarantees; higher QoS can increase broker and network overhead.
• Use userProperties only when the connected broker and clients support MQTT v5 properties.

How it works

MqttOptions is the public TypeScript configuration interface for selecting the MQTT microservice transport. It is one variant of MicroserviceOptions; its optional transport discriminator is Transport.MQTT, and its optional options object combines MQTT client connection settings with Nest-specific MQTT settings. microservice-configuration.interface.ts:25-33 microservice-configuration.interface.ts:142-168