/configuration-management

name: configuration-management
description: >
  Manage application configuration including environment variables, settings
  management, configuration hierarchies, secret management, feature flags, and
  12-factor app principles. Use for config, environment setup, or settings
  management.

Configuration Management

Table of Contents

• [Overview](#overview)
• [When to Use](#when-to-use)
• [Quick Start](#quick-start)
• [Reference Guides](#reference-guides)
• [Best Practices](#best-practices)

Overview

Comprehensive guide to managing application configuration across environments, including environment variables, configuration files, secrets, feature flags, and following 12-factor app methodology.

When to Use

• Setting up configuration for different environments
• Managing secrets and credentials
• Implementing feature flags
• Creating configuration hierarchies
• Following 12-factor app principles
• Migrating configuration to cloud services
• Implementing dynamic configuration
• Managing multi-tenant configurations

Quick Start

Minimal working example:

# .env.development
NODE_ENV=development
PORT=3000
DATABASE_URL=postgresql://localhost:5432/myapp_dev
REDIS_URL=redis://localhost:6379
LOG_LEVEL=debug
API_KEY=dev-api-key-12345

# .env.production
NODE_ENV=production
PORT=8080
DATABASE_URL=${DATABASE_URL}  # From environment
REDIS_URL=${REDIS_URL}
LOG_LEVEL=info
API_KEY=${API_KEY}  # From secret manager

# .env.test
NODE_ENV=test
DATABASE_URL=postgresql://localhost:5432/myapp_test
LOG_LEVEL=error

Reference Guides

Detailed implementations in the `references/` directory:

| Guide | Contents | |---|---| | [Environment Variables](references/environment-variables.md) | Environment Variables | | [Configuration Hierarchies](references/configuration-hierarchies.md) | Configuration Hierarchies | | [Secret Management](references/secret-management.md) | Secret Management | | [Feature Flags](references/feature-flags.md) | Feature Flags | | [12-Factor App Configuration](references/12-factor-app-configuration.md) | 12-Factor App Configuration | | [Configuration Validation](references/configuration-validation.md) | Configuration Validation | | [Dynamic Configuration (Remote Config)](references/dynamic-configuration-remote-config.md) | Dynamic Configuration (Remote Config) |

Best Practices

✅ DO

• Store configuration in environment variables
• Use different config files per environment
• Validate configuration on startup
• Use secret managers for sensitive data
• Never commit secrets to version control
• Provide sensible defaults
• Document all configuration options
• Use type-safe configuration objects
• Implement configuration hierarchy (base + overrides)
• Use feature flags for gradual rollouts
• Follow 12-factor app principles
• Implement graceful degradation for missing config
• Cache secrets to reduce API calls

❌ DON'T

• Hardcode configuration in source code
• Commit .env files with real secrets
• Use different config formats across services
• Store secrets in plain text
• Expose configuration through APIs
• Use production credentials in development
• Ignore configuration validation errors
• Access process.env directly everywhere
• Store configuration in databases (circular dependency)
• Mix configuration with business logic