NodeJS Microservices with NestJS, Kafka, and Kubernetes - Part 3

api-services.controller.ts

import {
  Controller,
  Get,
  Post,
  Body,
  Patch,
  Param,
  Delete,
} from '@nestjs/common';
import { ServicesService } from './services.service';
import { CreateServiceDto, UpdateServiceDto } from '@limascloud/common-dto';

@Controller('services')
export class ServicesController {
  constructor(private readonly servicesService: ServicesService) {}

  @Post()
  create(@Body() createServiceDto: CreateServiceDto) {
    return this.servicesService.create(createServiceDto);
  }

  @Get()
  findAll() {
    return this.servicesService.findAll();
  }

  @Get(':id')
  findOne(@Param('id') id: string) {
    return this.servicesService.findOne(+id);
  }

  @Patch(':id')
  update(@Param('id') id: string, @Body() updateServiceDto: UpdateServiceDto) {
    return this.servicesService.update(+id, updateServiceDto);
  }

  @Delete(':id')
  remove(@Param('id') id: string) {
    return this.servicesService.remove(+id);
  }
}

api-services.service.ts

import { Inject, Injectable } from '@nestjs/common';
import { CreateServiceDto, UpdateServiceDto } from '@limascloud/common-dto';
import { Producer } from '@nestjs/microservices/external/kafka.interface';
import { Logger } from '@nestjs/common';

@Injectable()
export class ServicesService {
  constructor(@Inject('KAFKA_PRODUCER') private kafkaProducer: Producer) {}

  create(createServiceDto: CreateServiceDto) {
    const id = Math.floor(Math.random() * 100);
    this.sendKafkaEvent(`${id}`, {
      eventType: 'ServiceCreated',
      id,
      ...createServiceDto,
    });
    return 'This action adds a new service';
  }

  findAll() {
    return `This action returns all services`;
  }

  findOne(id: number) {
    return `This action returns a #${id} service`;
  }

  update(id: number, updateServiceDto: UpdateServiceDto) {
    updateServiceDto.id = id;
    this.sendKafkaEvent(`${id}`, {
      eventType: 'ServiceUpdated',
      ...updateServiceDto,
    });
    return `This action updates a #${id} service`;
  }

  remove(id: number) {
    this.sendKafkaEvent(`${id}`, { eventType: 'ServiceDeleted', id });
    return `This action removes a #${id} service`;
  }

  sendKafkaEvent(key, value) {
    const message = { key, value: JSON.stringify(value) };
    Logger.debug(
      `sending message: ${JSON.stringify(message, null, 2)}`,
      'ServicesService',
    );
    this.kafkaProducer.send({
      topic: 'services',
      messages: [{ key, value: JSON.stringify(value) }],
    });
  }
}

convert-to-monorepo.sh

#!/bin/bash


cd api
# creates a blank microservices project under apps/microservices and converts the api project in a monorepo. Also moves current api code to apps/api
nest g app microservices

# Delete all generated microservices code and copy original content from the original project
rm -rf apps/microservices/src
cp -r ../microservices/src apps/microservices

# Move to the root of the repository. It's time to delete the old microservices project and move all files under api to the root of the repository
cd ..
rm -rf microservices api/README.md
mv api/.* .
mv api/* .

# Remove empty api folder and install necessary dependencies for the microservices project (these where listed in the original microservices/package.json)
rm -rf api
npm i @nestjs/event-emitter class-transformer

# OPTIONAL, open package.json, modify name property to microservices-nestjs-k8 instead of api

lib-dto-index.ts

export * from './event.dto';
export * from './create-service.dto';
export * from './delete-service.dto';
export * from './kafka-service.dto';
export * from './update-service.dto';

lib-index.ts

export * from './common-dto.module';
export * from './common-dto.service';
export * from './services/dto';

microservices-services.controller.ts

import { Controller, Logger, ValidationPipe } from '@nestjs/common';
import { EventPattern, Payload } from '@nestjs/microservices';
import { EventEmitter2, OnEvent } from '@nestjs/event-emitter';
import {
  KafkaServiceDto,
  CreateServiceDto,
  UpdateServiceDto,
  DeleteServiceDto,
} from '@limascloud/common-dto';

@Controller()
export class ServicesController {
  constructor(private eventEmitter: EventEmitter2) {}

  @EventPattern('services')
  serviceEvent(@Payload(new ValidationPipe()) { value }: KafkaServiceDto) {
    Logger.debug(value, 'ServicesController - serviceEvent');
    this.eventEmitter.emit(value.eventType, value);
  }

  @OnEvent('ServiceCreated')
  handleServiceCreatedEvent(createServiceDto: CreateServiceDto) {
    Logger.debug(
      createServiceDto,
      'ServicesController - handleServiceCreatedEvent',
    );
  }

  @OnEvent('ServiceUpdated')
  handleServiceUpdatedEvent(updateServiceDto: UpdateServiceDto) {
    Logger.debug(
      updateServiceDto,
      'ServicesController - handleServiceUpdatedEvent',
    );
  }

  @OnEvent('ServiceDeleted')
  handleServiceDeletedEvent(deleteServiceDto: DeleteServiceDto) {
    Logger.debug(
      deleteServiceDto,
      'ServicesController - handleServiceDeletedEvent',
    );
  }
}

move-dtos-to-new-lib.sh

#!/bin/bash

# Moves dtos from microservices project to new created library, and deletes the dtos from the api projects.
# File relative references to dtos needs to be modified to new lib location.

# From the repository root directory
mkdir -p libs/common-dto/src/services/dto
touch libs/common-dto/src/services/dto/index.ts
mv apps/microservices/src/services/dto/* libs/common-dto/src/services/dto
rm -rf apps/microservices/src/services/dto apps/api/src/services/dto