---

name: NestJS Configuration description: Environment variables validation and ConfigModule setup. metadata: labels: [nestjs, config, env] triggers: files: ['.env', 'app.module.ts', '**/config.ts'] keywords: [ConfigModule, Joi, env]

NestJS Configuration Standards

Setup

1. Library: Use @nestjs/config.
2. Initialization: Import ConfigModule.forRoot({ isGlobal: true }) in AppModule.

Validation

• Mandatory: Validate environment variables at startup.
• Tool: Use joi or a custom validation class.
• Effect: The app must crash immediately if a required env var (e.g., DB_URL) is missing.

Copy// app.module.ts
ConfigModule.forRoot({
  validationSchema: Joi.object({
    NODE_ENV: Joi.string()
      .valid('development', 'production')
      .default('development'),
    PORT: Joi.number().default(3000),
    DATABASE_URL: Joi.string().required(),
  }),
});

Usage

• Injection: Inject ConfigService to access values.
• Typing: Avoid magic strings. Use a type-safe getter helper or a dedicated configuration object/interface.
• Secrets: Never commit .env files. Add .env* to .gitignore.