Environment Variable Management

Beginner8 min

Manage environment variables securely with dotenv, validation, and type-safe configuration for Node.js applications.

Prerequisites

-Node.js installed

Steps

Install and configure dotenv

Set up dotenv to load environment variables from a .env file during development.

$ npm install dotenv echo 'require("dotenv").config();' | cat - app.js > /tmp/app.js && mv /tmp/app.js app.js

Load dotenv as early as possible in your entry file, before importing any modules that use env vars.

Create .env and .env.example files

Create the environment file for local development and a template for team onboarding.

$ cat <<'EOF' > .env NODE_ENV=development PORT=3000 DATABASE_URL=postgresql://localhost:5432/mydb JWT_SECRET=dev-secret-change-in-production REDIS_URL=redis://localhost:6379 EOF # Create template without secret values sed 's/=.*/=/' .env > .env.example

Never commit .env to version control. Always commit .env.example as a template for other developers.

Add .env to .gitignore

Ensure the .env file with real values is never committed to the repository.

$ echo '.env' >> .gitignore && echo '.env.local' >> .gitignore

Validate environment variables at startup

Add runtime validation to fail fast if required environment variables are missing.

$ cat <<'EOF' > config.js require('dotenv').config(); const required = ['DATABASE_URL', 'JWT_SECRET']; const missing = required.filter(key => !process.env[key]); if (missing.length > 0) { console.error('Missing required env vars:', missing.join(', ')); process.exit(1); } module.exports = { port: parseInt(process.env.PORT || '3000', 10), nodeEnv: process.env.NODE_ENV || 'development', databaseUrl: process.env.DATABASE_URL, jwtSecret: process.env.JWT_SECRET, redisUrl: process.env.REDIS_URL || 'redis://localhost:6379', isDev: process.env.NODE_ENV !== 'production' }; EOF

Parse numbers and booleans from env vars immediately in the config module. Never parse process.env values inline throughout your code.

Full Script

full-script.sh

#!/bin/bash
set -euo pipefail

# Node.js Environment Variable Setup

echo "==> Installing dotenv..."
npm install dotenv 2>/dev/null || echo "dotenv already installed"

echo "==> Creating .env file..."
if [ ! -f .env ]; then
  cat > .env <<'EOF'
NODE_ENV=development
PORT=3000
DATABASE_URL=postgresql://localhost:5432/mydb
JWT_SECRET=change-this-in-production
REDIS_URL=redis://localhost:6379
LOG_LEVEL=debug
EOF
  echo "  Created .env"
else
  echo "  .env already exists, skipping"
fi

echo "==> Creating .env.example..."
sed 's/=.*/=/' .env > .env.example
echo "  Created .env.example"

echo "==> Updating .gitignore..."
for PATTERN in ".env" ".env.local" ".env.production"; do
  if ! grep -q "^${PATTERN}$" .gitignore 2>/dev/null; then
    echo "${PATTERN}" >> .gitignore
    echo "  Added ${PATTERN} to .gitignore"
  fi
done

echo "==> Creating config module..."
cat > config.js <<'EOF'
require('dotenv').config();

const required = ['DATABASE_URL', 'JWT_SECRET'];
const missing = required.filter(key => !process.env[key]);

if (missing.length > 0) {
  console.error('FATAL: Missing required env vars:', missing.join(', '));
  console.error('Copy .env.example to .env and fill in values.');
  process.exit(1);
}

module.exports = {
  port: parseInt(process.env.PORT || '3000', 10),
  nodeEnv: process.env.NODE_ENV || 'development',
  databaseUrl: process.env.DATABASE_URL,
  jwtSecret: process.env.JWT_SECRET,
  redisUrl: process.env.REDIS_URL || 'redis://localhost:6379',
  logLevel: process.env.LOG_LEVEL || 'info',
  isDev: process.env.NODE_ENV !== 'production',
  isProd: process.env.NODE_ENV === 'production'
};
EOF

echo ""
echo "==> Setup complete. Usage:"
echo "  const config = require('./config');"
echo "  console.log(config.port); // 3000"

FAQ

Discussion

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#!/bin/bash set -euo pipefail # Node.js Environment Variable Setup echo "==> Installing dotenv..." npm install dotenv 2>/dev/null || echo "dotenv already installed" echo "==> Creating .env file..." if [ ! -f .env ]; then cat > .env <<'EOF' NODE_ENV=development PORT=3000 DATABASE_URL=postgresql://localhost:5432/mydb JWT_SECRET=change-this-in-production REDIS_URL=redis://localhost:6379 LOG_LEVEL=debug EOF echo " Created .env" else echo " .env already exists, skipping" fi echo "==> Creating .env.example..." sed 's/=.*/=/' .env > .env.example echo " Created .env.example" echo "==> Updating .gitignore..." for PATTERN in ".env" ".env.local" ".env.production"; do if ! grep -q "^${PATTERN}$" .gitignore 2>/dev/null; then echo "${PATTERN}" >> .gitignore echo " Added ${PATTERN} to .gitignore" fi done echo "==> Creating config module..." cat > config.js <<'EOF' require('dotenv').config(); const required = ['DATABASE_URL', 'JWT_SECRET']; const missing = required.filter(key => !process.env[key]); if (missing.length > 0) { console.error('FATAL: Missing required env vars:', missing.join(', ')); console.error('Copy .env.example to .env and fill in values.'); process.exit(1); } module.exports = { port: parseInt(process.env.PORT || '3000', 10), nodeEnv: process.env.NODE_ENV || 'development', databaseUrl: process.env.DATABASE_URL, jwtSecret: process.env.JWT_SECRET, redisUrl: process.env.REDIS_URL || 'redis://localhost:6379', logLevel: process.env.LOG_LEVEL || 'info', isDev: process.env.NODE_ENV !== 'production', isProd: process.env.NODE_ENV === 'production' }; EOF echo "" echo "==> Setup complete. Usage:" echo " const config = require('./config');" echo " console.log(config.port); // 3000"