# KafkaConfig

**Kind:** Interface

**Source:** [`packages/microservices/external/kafka.interface.ts`](https://github.com/nestjs/nest/blob/master/packages/microservices/external/kafka.interface.ts#L60)

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

`KafkaConfig` defines the connection, authentication, timeout, and retry settings used to create a Kafka client for the microservices transport layer. It supports static or dynamically resolved brokers, optional TLS, SASL authentication, and configurable request retry behavior.

## Properties

| Property | Type |
|---|---|
| `brokers` | `string[] | BrokersFunction` |
| `ssl` | `tls.ConnectionOptions | boolean` |
| `sasl` | `SASLOptions | Mechanism` |
| `clientId` | `string` |
| `connectionTimeout` | `number` |
| `authenticationTimeout` | `number` |
| `reauthenticationThreshold` | `number` |
| `requestTimeout` | `number` |
| `enforceRequestTimeout` | `boolean` |
| `retry` | `RetryOptions` |
| `socketFactory` | `ISocketFactory` |
| `logLevel` | `logLevel` |
| `logCreator` | `logCreator` |

## Diagram

```mermaid
graph LR
  App[Microservice Application] --> Config[KafkaConfig]
  Config --> Brokers[brokers<br/>string[] or BrokersFunction]
  Config --> Security[ssl and sasl]
  Config --> Identity[clientId]
  Config --> Timeouts[Connection and Request Timeouts]
  Config --> Retry[retry Options]
  Brokers --> Kafka[Kafka Cluster]
  Security --> Kafka
  Identity --> Kafka
  Timeouts --> Kafka
  Retry --> Kafka
```

## Usage

```ts
import type { KafkaConfig } from '@nestjs/microservices';

const kafkaConfig: KafkaConfig = {
  clientId: 'orders-service',
  brokers: ['kafka-1.example.com:9092', 'kafka-2.example.com:9092'],
  ssl: true,
  sasl: {
    mechanism: 'plain',
    username: process.env.KAFKA_USERNAME!,
    password: process.env.KAFKA_PASSWORD!,
  },
  connectionTimeout: 10_000,
  authenticationTimeout: 10_000,
  reauthenticationThreshold: 10_000,
  requestTimeout: 30_000,
  enforceRequestTimeout: true,
  retry: {
    retries: 8,
    initialRetryTime: 300,
  },
};
```

## AI Coding Instructions

- Provide at least one reachable Kafka broker through `brokers`; use a `BrokersFunction` only when broker discovery must be resolved dynamically.
- Match `ssl` and `sasl` settings to the Kafka cluster security configuration; enabling SASL without valid credentials will prevent client startup.
- Set a stable, unique `clientId` per service to make Kafka logs, metrics, and broker-side diagnostics easier to trace.
- Keep timeout and retry values aligned with deployment networking conditions, especially when connecting to managed or cross-region Kafka clusters.
- Enable `enforceRequestTimeout` when requests must fail predictably instead of waiting indefinitely for broker responses.