ConsumerConfig

Kind: Interface

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

Part of: Microservices

ConsumerConfig defines configuration options for a Kafka consumer used by the microservices Kafka transport. It controls consumer group membership, partition assignment and rebalancing behavior, heartbeat/session timing, and message fetch batch limits.

Properties

Diagram

mermaid
graph LR
  App[Microservice Consumer] --> Config[ConsumerConfig]
  Config --> Group[groupId]
  Config --> Assignment[partitionAssigners]
  Config --> Rebalancing[Session, rebalance, and heartbeat settings]
  Config --> Fetching[Fetch size and wait-time settings]
  Group --> Kafka[Kafka Consumer Group]
  Assignment --> Kafka
  Rebalancing --> Kafka
  Fetching --> Kafka

Usage

ts
import type { ConsumerConfig } from './kafka.interface';

const consumerConfig: ConsumerConfig = {
  groupId: 'billing-service',
  partitionAssigners: [],
  metadataMaxAge: 300_000,
  sessionTimeout: 30_000,
  rebalanceTimeout: 60_000,
  heartbeatInterval: 3_000,
  maxBytesPerPartition: 1_048_576,
  minBytes: 1,
  maxBytes: 10_485_760,
  maxWaitTimeInMs: 5_000,
};

// Pass consumerConfig to the Kafka transport/client initialization.

AI Coding Instructions

• Use a stable, service-specific groupId; consumers sharing a group ID load-balance partitions.
• Keep heartbeatInterval meaningfully lower than sessionTimeout to prevent unintended consumer removal.
• Ensure maxBytes is large enough for the expected aggregate batch size and is compatible with broker fetch limits.
• Configure partitionAssigners consistently across consumers in the same group to avoid rebalance compatibility issues.
• Treat timeout and fetch-size changes as operational tuning values; validate them against message volume and processing duration.

How it works

ConsumerConfig is an exported TypeScript interface representing the KafkaJS consumer-creation options in this repository’s Kafka type surface; the file explicitly states that it contains KafkaJS types only, not NestJS logic. packages/microservices/external/kafka.interface.ts:1-8 A Kafka instance accepts this type as the required argument to consumer() and returns a Consumer. packages/microservices/external/kafka.interface.ts:19-24