ProducerConfig

Kind: Interface

Source: packages/microservices/external/kafka.interface.ts

Part of: Microservices

ProducerConfig defines Kafka producer-specific options used when configuring a microservice client. It controls partitioning, retries, metadata refresh behavior, topic creation, and transactional delivery guarantees.

Properties

Diagram

mermaid
graph LR
  A[Kafka Microservice Client] --> B[ProducerConfig]
  B --> C[Custom Partitioner]
  B --> D[Retry Options]
  B --> E[Topic Metadata Settings]
  B --> F[Idempotent Producer]
  B --> G[Transactional Producer]
  G --> H[transactionalId]
  G --> I[transactionTimeout]
  B --> J[maxInFlightRequests]

Usage

ts
import { Transport } from '@nestjs/microservices';
import type { ProducerConfig } from '@nestjs/microservices/external/kafka.interface';

const producerConfig: ProducerConfig = {
  retry: {
    retries: 5,
    initialRetryTime: 300,
  },
  metadataMaxAge: 300_000,
  allowAutoTopicCreation: false,
  idempotent: true,
  transactionalId: 'orders-producer-1',
  transactionTimeout: 30_000,
  maxInFlightRequests: 1,
};

const kafkaOptions = {
  transport: Transport.KAFKA,
  options: {
    client: {
      clientId: 'orders-service',
      brokers: ['localhost:9092'],
    },
    producer: producerConfig,
  },
};

AI Coding Instructions

• Configure idempotent: true with a stable transactionalId when producers require exactly-once or transactional delivery semantics.
• Keep maxInFlightRequests low, typically 1, when ordering and idempotent delivery guarantees are required.
• Set allowAutoTopicCreation: false in production and provision topics explicitly through infrastructure tooling.
• Use retry settings appropriate for broker availability and transient network failures; avoid excessively aggressive retry loops.
• Provide createPartitioner only when default Kafka partition selection does not meet message routing requirements.

How it works

ProducerConfig is an exported TypeScript interface that describes the optional configuration argument accepted by Kafka.producer(config?). The file states that its declarations are intended to represent KafkaJS package types only. kafka.interface.ts:1-8 kafka.interface.ts:19-24

All of its properties are optional, so the type itself requires no fields. kafka.interface.ts:110-119

Its fields are:

• createPartitioner?: ICustomPartitioner — a zero-argument function returning a partition-selection function. That returned function receives topic, partitionMetadata, and message, and returns a partition number. kafka.interface.ts:111 kafka.interface.ts:129-135
• retry?: RetryOptions — retry settings: optional maxRetryTime, initialRetryTime, factor, multiplier, retries, and an optional asynchronous restartOnFailure callback receiving an Error and returning Promise<boolean>. kafka.interface.ts:112 kafka.interface.ts:253-260
• metadataMaxAge?: number, allowAutoTopicCreation?: boolean, idempotent?: boolean, transactionalId?: string, transactionTimeout?: number, and maxInFlightRequests?: number. kafka.interface.ts:113-118

Nest exposes this type as KafkaOptions.options.producer. microservice-configuration.interface.ts:333-355 The Kafka client creates a producer with this.options.producer || {}, then registers producer event listeners and connects it. client-kafka.ts:184-186 The Kafka server passes this.options.producer to producer(), registers producer event listeners, and connects the resulting producer. server-kafka.ts:107-118

This interface contains no executable validation, error handling, or side effects. The observable configuration interpretation, validation, defaults, and errors belong to the externally declared KafkaJS Kafka.producer() implementation rather than code in this repository. kafka.interface.ts:1-8 kafka.interface.ts:19-24