Environment Variable

Definitions

1. A dynamic value stored outside the application code that configures behavior at runtime — database URLs, API keys, feature flags. The answer to 'how do I store secrets without hardcoding them' and the reason .env files exist.

   In plain English: A setting stored outside your code that the program reads when it starts — like keeping your passwords in a safe instead of written on a sticky note.

2. The Twelve-Factor App methodology mandates environment variables for configuration, strictly separating config from code. The .env file pattern (loaded by dotenv libraries) provides a convenient local development experience while keeping secrets out of version control — assuming you don't accidentally commit the .env file.

   Example: 'DATABASE_URL, REDIS_URL, API_KEY — all in environment variables, never in code. And for the love of everything, add .env to your .gitignore.'

   Source: Twelve-Factor App

Related Terms

• Twelve-Factor App
• Webhook Secret
• Secret Rotation
• Config as Code
• twelve-factor app
• Environment Variable
• Manifest
• Secret
• URL Parser
• Validation
• Config Schema
• Config Store
• Configuration Drift
• Configuration Service
• Custom Resolver