feat(microservices): add IncomingKafkaMessage interface

[ruscon]

Feature Request

feat(microservice): add Kafka transport IncomingMessage interface

Is your feature request related to a problem? Please describe.

In the documentation https://docs.nestjs.com/microservices/kafka IncomingMessage interface is indicated

interface IncomingMessage {
  topic: string;
  partition: number;
  timestamp: string;
  size: number;
  attributes: number;
  offset: string;
  key: any;
  value: any;
  headers: Record<string, any>;
}

This interface is missing in the @nestjs/microservice

Describe the solution you'd like

Maybe it should be added to the @nestjs/microservice Kafka interfaces?

the real incoming message example

{
  magicByte: 2,
  attributes: 0,
  timestamp: '1582833272310',
  offset: '28',
  key: null,
  value: { action: 'test', body: { order_number: 'test' } },
  headers: { 'app.name': 'Conduktor' },
  isControlRecord: false,
  batchContext: {
    firstOffset: '28',
    firstTimestamp: '1582833272310',
    partitionLeaderEpoch: 0,
    inTransaction: false,
    isControlBatch: false,
    lastOffsetDelta: 0,
    producerId: '-1',
    producerEpoch: -1,
    firstSequence: -1,
    maxTimestamp: '1582833272310',
    magicByte: 2
  },
  topic: 'notify',
  partition: 0
}

so, the interface could be

interface IncomingKafkaMessage<V = any, K = any, H = Record<string, any>> {
  magicByte: number;
  topic: string;
  partition: number;
  timestamp: string;
  size: number;
  attributes: number;
  offset: string;
  key: K;
  value: V;
  headers: H;
  isControlRecord: boolean;
  batchContext: {
    firstOffset:  string;
    firstTimestamp: string;
    partitionLeaderEpoch: number;
    inTransaction: boolean;
    isControlBatch: boolean;
    lastOffsetDelta: number;
    producerId: string;
    producerEpoch: number;
    firstSequence: number;
    maxTimestamp: string;
    magicByte: number;
 }
}

[kamilmysliwiec]

Would you like to create a PR?

[ruscon]

Yep, if you OK with the IncomingKafkaMessage interface.

[kamilmysliwiec]

I've spent some time on this and I decided that we shouldn't be adding interfaces unrelated to NestJS. This particular one should be added to the kafkajs library instead (or typings of this library). The IncomingMessage doesn't contain anything specifically related to NestJS.