NestJS Kafka - Check for topics in health check

Question

I'd like to check if my service is consuming a topic as part of my health check. I created a custom transport for Kafka:

export class KafkaCustomTransport extends ServerKafka {
  get kafkaClient(): Kafka {
    return this.client;
  }
}

And now I'd like to inject and access it in my health check module:

import { Controller, Get } from '@nestjs/common';
import { HealthCheckService, HttpHealthIndicator, HealthCheck } from '@nestjs/terminus';

@Controller('health')
export class HealthController {
  constructor(
    private health: HealthCheckService,
    private http: HttpHealthIndicator,
    private kafkaTransport: KafkaCustomTransport <- Something like this
  ) {}

  @Get()
  @HealthCheck()
  check() {
    return this.health.check([
      () => this.http.pingCheck('nestjs-docs', 'https://docs.nestjs.com'),
      () => this.kafkaTransport.client...........
    ]);
  }
}

Is there a way to do this? Is there a workaround?

Answer 1

Wrapped it in a provider which I can then get with @Inject:

export const kafkaProvider = {
    provide: "KAFKA",
    useFactory: (): KafkaCustomTransport => {
  
      const kafkaOptions: KafkaOptions["options"] = {};
  
      return new KafkaCustomTransport(options);
    },
    inject: [],
  };

In health check:

@Controller('health')
export class HealthController {
  constructor(
    private health: HealthCheckService,
    private http: HttpHealthIndicator,
    @Inject("KAFKA") private kafkaTransport: KafkaCustomTransport
  ) {}