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Documentation Index

Fetch the complete documentation index at: https://mintlify.com/ihfaz297/MND/llms.txt

Use this file to discover all available pages before exploring further.

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Backend Environment Variables

The backend uses a .env file in the MND-backend/ directory.

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Example .env File

# Google Distance Matrix API Key
# Get your key from: https://console.cloud.google.com/apis/credentials
GOOGLE_DM_API_KEY=your_api_key_here

# Server Configuration
PORT=3000
NODE_ENV=production

# JWT Secret for Auth Tokens (optional, auto-generated if not set)
JWT_SECRET=your_random_secret_key_here

# Email Configuration for Magic Links (optional)
EMAIL_FROM=noreply@yourdomain.com
EMAIL_SMTP_HOST=smtp.gmail.com
EMAIL_SMTP_PORT=587
EMAIL_SMTP_USER=your-email@gmail.com
EMAIL_SMTP_PASSWORD=your-app-password

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Required Variables

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GOOGLE_DM_API_KEY
string
required
Google Distance Matrix API key for calculating travel times and distances.How to get:
  1. Go to Google Cloud Console
  2. Enable Distance Matrix API
  3. Create credentials (API key)
  4. Restrict key to Distance Matrix API only
See Google APIs Setup for detailed instructions.

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Server Configuration

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PORT
number
default:"3000"
Port number the server listens on.Examples:
PORT=3000  # Default
PORT=8080  # Alternative
PORT=80    # HTTP (requires sudo)
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NODE_ENV
string
default:"development"
Environment mode. Affects logging and error handling.Valid values:
  • development - Verbose logging, detailed errors
  • production - Minimal logging, sanitized errors
  • test - Test mode

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Authentication (Optional)

The backend includes magic link authentication for user favorites.
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JWT_SECRET
string
Secret key for signing JWT tokens. Auto-generated if not provided.Generate a secure secret:
node -e "console.log(require('crypto').randomBytes(32).toString('hex'))"
Example:
JWT_SECRET=a1b2c3d4e5f6789abcdef0123456789abcdef0123456789abcdef012345678

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Email Configuration (Optional)

For sending magic link emails. If not configured, tokens are logged to console.
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EMAIL_FROM
string
Sender email address for magic links.Example:
EMAIL_FROM=noreply@university.edu
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EMAIL_SMTP_HOST
string
SMTP server hostname.Common providers:
  • Gmail: smtp.gmail.com
  • Outlook: smtp.office365.com
  • SendGrid: smtp.sendgrid.net
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EMAIL_SMTP_PORT
number
SMTP server port.Standard ports:
  • 587 - TLS (recommended)
  • 465 - SSL
  • 25 - Unencrypted (not recommended)
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EMAIL_SMTP_USER
string
SMTP authentication username (usually your email).
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EMAIL_SMTP_PASSWORD
string
SMTP authentication password.For Gmail: Use an App Password, not your regular password.

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Frontend Environment Variables

The React frontend uses Vite’s environment variable system.

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Create .env File

Create .env in MND-frontend/: 
# Backend API URL
VITE_API_BASE_URL=http://localhost:3000

# Google Maps API Key (for frontend maps, optional)
VITE_GOOGLE_MAPS_API_KEY=your_maps_api_key_here

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Vite Environment Variables

Vite environment variables must be prefixed with VITE_ to be exposed to the client.
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VITE_API_BASE_URL
string
required
Backend API base URL.Development:
VITE_API_BASE_URL=http://localhost:3000
Production (same server):
VITE_API_BASE_URL=/api  # Relative path
Production (separate server):
VITE_API_BASE_URL=https://api.yourdomain.com
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VITE_GOOGLE_MAPS_API_KEY
string
Google Maps JavaScript API key for map display (optional).Note: This is different from the Distance Matrix API key. This key is exposed to clients, so restrict it to your domain.

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Using Environment Variables in Code

In React components: 
const apiUrl = import.meta.env.VITE_API_BASE_URL;
const mapsKey = import.meta.env.VITE_GOOGLE_MAPS_API_KEY;

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Flutter Environment Variables

The Flutter app uses flutter_dotenv package.

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Create .env File

Create .env in mnd_flutter/: 
# Backend API URL
API_BASE_URL=http://192.168.1.100:3000

# Google Maps API Key (Android/iOS)
GOOGLE_MAPS_API_KEY=your_mobile_maps_api_key_here
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API_BASE_URL
string
required
Backend API base URL.Local development (emulator):
# Android emulator
API_BASE_URL=http://10.0.2.2:3000

# iOS simulator
API_BASE_URL=http://localhost:3000
Local development (physical device):
API_BASE_URL=http://192.168.1.100:3000  # Your computer's network IP
Production:
API_BASE_URL=https://api.yourdomain.com
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GOOGLE_MAPS_API_KEY
string
Google Maps API key for Android/iOS.Restrict this key to your app’s bundle ID/package name.

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Using in Flutter Code

import 'package:flutter_dotenv/flutter_dotenv.dart';

final apiUrl = dotenv.env['API_BASE_URL'];
final mapsKey = dotenv.env['GOOGLE_MAPS_API_KEY'];

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Load .env on Startup

In main.dart: 
import 'package:flutter_dotenv/flutter_dotenv.dart';

void main() async {
  await dotenv.load(fileName: ".env");
  runApp(MyApp());
}

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.env.example Template

Provide a template for other developers: MND-backend/.env.example: 
# Copy this file to .env and fill in your values

# Google Distance Matrix API Key
GOOGLE_DM_API_KEY=your_api_key_here

# Server Configuration
PORT=3000
NODE_ENV=development

# Optional: Email for magic links
# EMAIL_FROM=noreply@example.com
# EMAIL_SMTP_HOST=smtp.gmail.com
# EMAIL_SMTP_PORT=587
# EMAIL_SMTP_USER=your-email@gmail.com
# EMAIL_SMTP_PASSWORD=your-app-password

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Security Best Practices

Never commit .env files to version control!

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Add to .gitignore

# Environment variables
.env
.env.local
.env.production
.env.development

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Rotate API Keys

  • Rotate Google API keys every 90 days
  • Use different keys for development and production
  • Restrict keys to specific APIs and domains

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Server-Side vs Client-Side

Server-side (backend .env):
  • Keys are never exposed to clients
  • Can contain sensitive secrets
  • Used for Distance Matrix API, email passwords, etc.
Client-side (Vite/Flutter .env):
  • Keys are exposed in compiled code
  • Must be restricted by domain/bundle ID
  • Only use for client-side APIs (Maps JavaScript API)

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Environment-Specific Configuration

Create multiple environment files: 
.env.development   # Local development
.env.staging       # Staging server
.env.production    # Production server
Load based on NODE_ENV: 
import dotenv from 'dotenv';

const envFile = `.env.${process.env.NODE_ENV || 'development'}`;
dotenv.config({ path: envFile });

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Verification

Test that environment variables are loaded: 
# Backend
node -e "require('dotenv').config(); console.log(process.env.GOOGLE_DM_API_KEY)"

# Should output your API key (not 'undefined')

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Next Steps

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