Env vars in main file

Using environment variables in the main file.

If you notice, in the main file, the value used for the app port is obtained from the .env and, if not found, is defaulted to 3000. In here, we cannot use a configuration namespace because the application is still being initialized, but we can use the ConfigService to access the env.

First, let's create, at the top of the .env file, the variable for the port. Remember to also add it in the .env.example file.

APP_PORT = 3000

After that, we should also validate it in the validation schema, in the env.constants file. It can use the same validation as the one for the database port.

Then, in the main file, we can get a reference to the ConfigService from the app, and then obtain the port value and use it.

async function bootstrap() {
  const app = await NestFactory.create(AppModule);

  const configService = app.get(ConfigService);
  const port = configService.get<number>('APP_PORT');

  await app.listen(port);
}

Commit - Using environment variables in main file