300. Configs

Setup Configs

• Configuration | NestJS - A progressive Node.js framework

1. save configuration files (environment variables), inside .env files
2. load .env files using @nest/config library
3. use the variables using process.env.[variable_name]

npm i --save @nestjs/config

@Module({
  imports: [
    ConfigModule.forRoot(),
    TypeOrmModule.forRoot({
      type: 'postgres',
      host: process.env.DATABASE_HOST,
      port: +process.env.DATABASE_PORT,
      username: process.env.DATABASE_USER,
      //...
    }),
  ],
})
export class AppModule {}

Custom .env Path

• Configuration | NestJS - A progressive Node.js framework
• we can also pass custom env file
  • by default ConfigModule.forRoot() looks for a .env file in the root directory of the application.
  • To specify another path for the .env file, use the envFilePath property

ConfigModule.forRoot({
  envFilePath: '.development.env',
});

• we can configure configmodule behavior by defining different options
  • ignoreEnvFile
    • this is useful to prevent configmodule from looking .env to load environment variables…this is useful for cases such as providing environment variables using hosting ui instead of .env

ConfigModule.forRoot({
	ignoreEnvFile: true
})

Using Config Service

• Configuration | NestJS - A progressive Node.js framework
• import the config module inside AppModule(so it can be available everywhere) using the .forRoot method
• inject config-service in the class you want to use use

@Module({
  imports: [
    ConfigModule.forRoot(),
  ],
})
export class AppModule {}

class CoffeeService{

	constructor(private readonly configService: ConfigService){
	
		const db_password = this.configService.get<string>('DATABASE_PASSWORD');
		
		//CAN ALSO WORK WITH DEFAULT VALUE
		const db_password = this.configService.get<string>('DATABASE_PASSWORD', 'password');
	}
}

it's possible to define different configurations per section of your app, and use config module to load them flexibly

always prefer using configService.get('key') instead of using process.env.key

Cache Environment Variables

• Configuration | NestJS - A progressive Node.js framework
• As accessing process.env can be slow, you can set the cache property of the options object passed to ConfigModule.forRoot() to increase the performance of ConfigService#get method when it comes to variables stored in process.env.

ConfigModule.forRoot({
  cache: true,
});

Config Validation

• Configuration | NestJS - A progressive Node.js framework
• we can use Joi to validate config variables
  • GitHub - hapijs/joi: The most powerful data validation library for JS
  • i.e is port a number, db connection string is required…
• if the configurations don't meet our criteria application will stop with meaning-full error.

npm install --save joi

ConfigModule.forRoot({
  validationSchema: Joi.object({
	DATABASE_HOST: Joi.required(),
	DATABASE_PORT: Joi.number().default(5432)
  })
}),

Using Config in main.ts

• Configuration | NestJS - A progressive Node.js framework
• While our config is a stored in a service, it can still be used in the main.ts file.
• This way, you can use it to store variables such as the application port or the CORS host.

const configService = app.get(ConfigService);
const port = configService.get('PORT');