Configuration API

Decorator-driven configuration management from environment variables with automatic validation.

What It Does

The Configuration API provides a NestJS-based system for populating TypeScript class models from environment variables using decorators and metadata reflection. It automates environment variable mapping, validation, and error reporting for configuration management.

Key Capabilities

Capability	Description
Decorator-Driven	`@Config()` decorator marks configuration points for automatic injection
Hierarchical Naming	Class-level prefixes and property-level customization
Automatic Validation	Integrates with class-validator for config validation
Type Safety	TypeScript class-based models with compile-time verification
NestJS Integration	Works as Injectable service with ConfigService
Error Logging	Clear formatting for validation errors
Environment Variable Conversion	Automatic SNAKE_CASE naming convention

Usage Pattern


@Config({base: 'BROWSER'})
export class BrowserConfigModel {
  @Config()
  @IsString()
  @IsUrl()
  baseURL = 'https://browser.example.com'
 
  @Config({envar: 'CUSTOM_NAME'})
  @IsNumber()
  port = 3000
}
 
// Populate and validate
const reflector = new ConfigReflector(configService)
const [model, errors] = await reflector.reflect(BrowserConfigModel)

Exports

@Config() - Decorator for configuration injection
ConfigReflector - Service for reflection and validation

Common Use Cases

Application configuration from environment
Type-safe config objects
Config validation at startup
Multi-environment configuration

What Customers Don’t Have to Build

Environment variable mapping
SNAKE_CASE conversion
Validation integration
Config reflection
Error logging
Type-safe config injection