# KafkaOptions

**Kind:** Interface

**Source:** [`packages/microservices/interfaces/microservice-configuration.interface.ts`](https://github.com/nestjs/nest/blob/master/packages/microservices/interfaces/microservice-configuration.interface.ts#L333)

**Part of:** [Microservices](subsystem-packages-microservices)

`KafkaOptions` configures a NestJS microservice that communicates through Apache Kafka. It combines Kafka client, consumer, producer, subscription, serialization, and message-parsing settings while enforcing `Transport.KAFKA` as the selected transport.

## Properties

| Property | Type |
|---|---|
| `transport` | `Transport.KAFKA` |
| `options` | `{ postfixId?: string; client?: KafkaConfig; consumer?: ConsumerConfig; run?: Omit<ConsumerRunConfig, 'eachBatch' | 'eachMessage'>; subscribe?: Omit<ConsumerSubscribeTopics, 'topics'>; producer?: ProducerConfig; send?: Omit<ProducerRecord, 'topic' | 'messages'>; serializer?: Serializer; deserializer?: Deserializer; parser?: KafkaParserConfig; producerOnlyMode?: boolean; }` |

## Diagram

```mermaid
graph LR
  A[KafkaOptions] --> B[transport: Transport.KAFKA]
  A --> C[options]

  C --> D[client: KafkaConfig]
  C --> E[consumer: ConsumerConfig]
  C --> F[run: ConsumerRunConfig]
  C --> G[subscribe: ConsumerSubscribeTopics]
  C --> H[producer: ProducerConfig]
  C --> I[send: ProducerRecord defaults]
  C --> J[serializer / deserializer]
  C --> K[parser: KafkaParserConfig]
  C --> L[producerOnlyMode]

  D --> M[Kafka Broker]
  E --> M
  H --> M
```

## Usage

```ts
import { NestFactory } from '@nestjs/core';
import { AppModule } from './app.module';
import { KafkaOptions, Transport } from '@nestjs/microservices';

async function bootstrap() {
  const kafkaOptions: KafkaOptions = {
    transport: Transport.KAFKA,
    options: {
      client: {
        clientId: 'billing-service',
        brokers: ['localhost:9092'],
      },
      consumer: {
        groupId: 'billing-consumer-group',
      },
      subscribe: {
        fromBeginning: false,
      },
      run: {
        autoCommit: true,
      },
      producer: {
        allowAutoTopicCreation: false,
      },
      send: {
        acks: -1,
      },
    },
  };

  const app = await NestFactory.createMicroservice(AppModule, kafkaOptions);
  await app.listen();
}

bootstrap();
```

## AI Coding Instructions

- Always set `transport` to `Transport.KAFKA`; this interface is specifically for Kafka-based microservices.
- Configure a unique `client.clientId` and stable `consumer.groupId` to avoid conflicts between deployed service instances.
- Do not provide `topics` in `subscribe`, `topic` or `messages` in `send`, or `eachBatch`/`eachMessage` in `run`; NestJS manages these values per handler and message operation.
- Use custom `serializer`, `deserializer`, or `parser` options when integrating with non-Nest producers or consumers that use different payload formats.
- Set `producerOnlyMode: true` for services that publish Kafka messages but do not register Kafka message handlers.