.env

LOADER=fileLoader
PORT=9000

.env.yaml

app:
  somePort: ${PORT:-12345}
  envLoader: fileLoader
  port: 5005
  apiPrefix: api-blob
  environment: development

app.module.ts

import { Module } from '@nestjs/common';
import { AppController } from './app.controller';
import { AppService } from './app.service';
import { TypedConfigModule, fileLoader } from 'nest-typed-config';
import { AppConfig } from '#config/configuration';

@Module({
  imports: [
    TypedConfigModule.forRoot({
      schema: AppConfig,
      load: fileLoader({ ignoreEnvironmentVariableSubstitution: false }),
    }),
  ],
  controllers: [AppController],
  providers: [AppService],
})
export class AppModule {}

configuration.ts

import { Transform, Type } from 'class-transformer';
import {
  IsArray,
  IsDefined,
  IsInt,
  IsNumber,
  IsOptional,
  IsString,
  ValidateNested,
} from 'class-validator';

export class GeneralConfig {
  @IsNumber()
  @Type(() => Number)
  public readonly somePort!: number;

  @IsInt()
  @IsOptional()
  public readonly port: number = 5005;

  @IsString()
  @IsOptional()
  public readonly envLoader: string;

  @IsString()
  @IsOptional()
  public readonly apiPrefix: string = 'api-blob';

  @IsString()
  @IsOptional()
  public readonly environment: string = 'development';
}

export class AppConfig {
  @Type(() => GeneralConfig)
  @ValidateNested()
  @IsDefined()
  public readonly app: GeneralConfig;
}

main.ts

import { NestFactory } from '@nestjs/core';
import { AppModule } from './app.module';
import { json, urlencoded } from 'body-parser';
import * as cookieParser from 'cookie-parser';
import { Logger, ValidationPipe } from '@nestjs/common';
import { AppConfig } from '#config/configuration';

async function bootstrap() {
  const environment = process.env.NODE_ENV || 'development';

  const app = await NestFactory.create(AppModule, {
    logger:
      environment === 'development'
        ? ['debug', 'log', 'warn', 'error']
        : ['log', 'warn', 'error'],
  });

  // validation pipe
  app.useGlobalPipes(new ValidationPipe());

  // body-parser
  app.use(urlencoded({ extended: true }));
  app.use(json({ limit: '1000mb' }));

  // cookie-parser
  app.use(cookieParser());

  // cors
  app.enableCors({ origin: true, credentials: true });

  // Pre setup
  const logger = new Logger();

  const configService = app.get(AppConfig);

  const apiPrefix = configService.app.apiPrefix;
  app.setGlobalPrefix(apiPrefix);

  const port = configService.app.port;

  console.log('SOME PORT');
  console.log(configService.app.somePort);

  await app.listen(port, () => {
    logger.log(`DTF Cron API is running at port ${port}`);
    logger.log(`API prefix: ${apiPrefix}`);
  });
}
bootstrap();