env-guard 🛡️

A lightweight and strict environment variable validator for Node.js apps. Ensure your app fails fast if required environment variables are missing, or auto-fill them with defaults.

Features

• 🛑 Fail Fast: Terminates the process aggressively if required process.env keys are missing.
• ⚙️ Auto-fill Defaults: Automatically sets fallback values if keys are not provided.
• 📦 Zero Dependencies: Extremely light.
• 🚀 Built for Modern Node: Written in TypeScript, ESM by default.

Installation

npm install env-guard

Usage

Import validateEnv at the very beginning of your application (e.g., index.js, server.js or main.ts), to ensure all environment variables are verified before the rest of your app runs.

import { validateEnv } from 'env-guard';

validateEnv({
  PORT: { required: true, default: "3000" },
  DATABASE_URL: { required: true },
  API_KEY: { required: false }
});

// If DATABASE_URL is missing, the app will log an error and exit with code 1.
// If PORT is missing, process.env.PORT will be set to "3000".

console.log(`Server starting on port ${process.env.PORT}`);

API

validateEnv(schema: EnvSchema): void

Validates the process.env against the provided schema.

• schema: An object where keys are the environment variable names and values are objects containing:
  • required (boolean): Whether the environment variable must be present.
  • default (string - optional): A fallback value to use if the environment variable is omitted or empty.

If validation fails, env-guard will output the missing keys to console.error and call process.exit(1).

License

MIT