Environment Config with dotenv

6 min read

Environment Config with dotenv

Hard-coding database URLs, API keys, or port numbers into source code is a security risk and makes deploying to different environments painful. The standard solution is to store configuration in environment variables and load them from a .env file during development.

bash

npm install dotenv

// src/index.ts — load as early as possible
import "dotenv/config";
import app from "./app";

const PORT = Number(process.env.PORT) || 3000;
const NODE_ENV = process.env.NODE_ENV || "development";

app.listen(PORT, () => {
  console.log(`[${NODE_ENV}] Server on port ${PORT}`);
});

bash

# .env (never commit this file)
PORT=4000
NODE_ENV=development
DATABASE_URL=postgresql://user:pass@localhost:5432/mydb
JWT_SECRET=super-secret-value

Add .env to .gitignore immediately. Commit only a .env.example file with placeholder values so team members know which variables are required.

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