WiFi Failover Utility

Automatic failover from WiFi to Android hotspot. When your primary WiFi network loses internet connectivity, this utility automatically commands your Android phone to enable hotspot and connects your Mac to it—all without manual intervention.

┌─ Detect connectivity loss ─────────────┐
│  (macOS daemon polls WiFi every 30s)   │
│                                        │
├─ Post to Cloudflare Worker ───────────┤
│  (triggers hotspot command)            │
│                                        │
├─ Android app polls Worker ────────────┤
│  (native app, every 5 seconds)         │
│                                        │
├─ Phone enables hotspot ───────────────┤
│  (automatically via native app)        │
│                                        │
└─ Mac connects to hotspot ─────────────┘
   (using stored WiFi password)

Requirements

• macOS (tested on Big Sur+)
• Android phone (Android 11+) with WiFi Failover App (native app - see android-app/)
• Cloudflare account with Workers KV (may require paid plan - ~$5/month)
• Python 3.8+

Note: Cloudflare Workers KV is required for storing daemon heartbeat state. The free tier may have limitations. A paid Workers plan (~$5/month) is recommended for reliable operation.

Quick Start (5 Minutes)

1. Install macOS Daemon

# Install via pip
pip install wifi-failover-utility

# Run interactive setup
wifi-failover setup

The setup wizard will guide you through:

• Configuring your phone's hotspot SSID
• Entering Cloudflare Worker URL & secret
• Storing hotspot password securely in macOS Keychain
• Auto-starting the daemon

2. Deploy Cloudflare Worker

Follow CLOUDFLARE_SETUP.md to deploy the relay Worker.

You'll need:

• A Cloudflare account with Workers KV enabled
• The Worker URL (e.g., https://wifi-failover.youraccount.workers.dev)
• A secret string for authentication

3. Install Android App

Download the APK and install:

adb install wifi-failover-v1.0.apk

Or build from source:

cd android-app
./gradlew assembleRelease
adb install app/build/outputs/apk/release/app-release-unsigned.apk

Configure the app:

1. Open "WiFi Failover" app
2. Go to Settings → Accessibility → Enable "WiFi Failover" service
3. Enter your Cloudflare Worker URL
4. Enter your Worker secret
5. Enter your phone's hotspot SSID
6. Tap "Start Monitoring"

The app will now poll every 5 seconds and automatically enable hotspot when the daemon goes offline.

4. Verify It's Working

# Check daemon status
wifi-failover status

# Test offline detection (pauses heartbeats for 20 seconds)
wifi-failover pause-heartbeat

# Watch Android logs to verify offline detection
adb logcat | grep WiFiFailoverWorker

# Resume heartbeats
wifi-failover resume-heartbeat

That's it! Your Mac will now automatically failover to your phone's hotspot when WiFi goes down.

Installation as Daemon

To run as a background service on Mac startup:

# Copy the launchd plist template
sudo cp launchd/com.wifi-failover.monitor.plist /Library/LaunchDaemons/

# Edit the plist with your username and paths
sudo nano /Library/LaunchDaemons/com.wifi-failover.monitor.plist

# Load it
sudo launchctl load /Library/LaunchDaemons/com.wifi-failover.monitor.plist

# Verify it's running
ps aux | grep wifi-failover

# Watch logs
tail -f /tmp/wifi-failover/monitor.log

Configuration

Configuration is stored in ~/.config/wifi-failover/config.json:

{
  "monitored_networks": ["901 EXT5G", "MyWiFi"],
  "hotspot_ssid": "Dhruv's iPhone",
  "worker_url": "https://wifi-failover.youraccount.workers.dev",
  "worker_secret": "your-random-secret-here"
}

Edit this file directly or rerun wifi-failover setup to reconfigure.

Commands

# Interactive setup (with option to start daemon)
wifi-failover setup

# Start monitoring in foreground (for testing)
wifi-failover start

# Start daemon in background
wifi-failover daemon

# Enable auto-start on login
wifi-failover enable-autostart

# Disable auto-start on login
wifi-failover disable-autostart

# Show current configuration and status
wifi-failover status

How It Works

macOS Daemon

• Runs continuously via launchd
• Checks WiFi network every 30 seconds
• Tests internet connectivity with ping to 8.8.8.8
• If 2+ consecutive failures: POSTs to Worker to enable hotspot
• Waits for hotspot to activate, then connects via networksetup
• If 3+ consecutive successes: disables hotspot command

Cloudflare Worker

• Stores state in KV storage (10-min TTL)
• POST /api/command/enable - Trigger hotspot
• POST /api/command/disable - Cancel hotspot
• GET /api/status - Check command status
• POST /api/acknowledge - Confirm action completed

Android (WiFi Failover App - Native)

• Runs as background WorkManager task every 5 seconds
• GETs /api/status to check if hotspot should be enabled
• Parses JSON response in Kotlin
• If daemon_status = "online": keeps hotspot disabled
• If daemon_status = "offline": enables hotspot automatically
• POSTs /api/acknowledge to confirm action
• Auto-starts on device boot via BootCompleteReceiver
• Respects lock/sleep detection from daemon (paused status)

Troubleshooting

Daemon not running

# Check status
ps aux | grep wifi-failover

# Check launchd status
sudo launchctl list | grep wifi-failover

# View logs
tail -f /tmp/wifi-failover/monitor.log

Hotspot not triggering (Android App)

• Verify "Start Monitoring" button shows "Stop Monitoring" (toggle is ON)
• Check battery optimization: Settings → Battery → App not restricted
• Check permissions: Settings → Apps → WiFi Failover → Permissions
• Check Device Admin permission is enabled
• Check logs: adb logcat | grep WiFiFailover
• Verify Worker URL and Secret are correct in app settings
• Test Worker manually: curl https://your-worker/health
• On Android 12+, some versions limit hotspot control (see limitations)

Can't connect to hotspot

• Verify password is stored in Keychain:

  security find-generic-password -wa "Dhruv's iPhone"
  

• Test manual connection first:

  networksetup -setairportnetwork en0 "Dhruv's iPhone" "your-password"
  

Worker not responding

curl https://your-worker/health
curl https://your-worker/api/status

File Structure

wifi-failover-utility/
├── wifi_failover/
│   ├── __init__.py
│   ├── cli.py                  # Interactive CLI
│   ├── config.py               # Configuration management
│   └── monitor.py              # Main daemon logic
├── android-app/                # Native Android app
│   └── app/src/main/kotlin/
├── launchd/
│   └── com.wifi-failover.monitor.plist
├── src/
│   └── index.js                # Cloudflare Worker code
├── setup.py
├── README.md
├── CLOUDFLARE_SETUP.md
└── LICENSE

Security Notes

• Your Cloudflare Worker secret is stored in plaintext in the config file
• Store config file securely (it contains sensitive credentials)
• Consider rotating the secret periodically
• Don't commit config files to version control

Limitations

• Requires phone to be nearby (hotspot range ~30ft)
• If both networks fail, system can't help
• Hotspot password must be stored in macOS Keychain
• Android device must have internet to enable hotspot
• Some Android 12+ devices restrict hotspot control via WifiManager
• App polling every 5 seconds (battery usage ~1-2% per hour)

Development

# Clone and install in development mode
git clone https://github.com/yourusername/wifi-failover-utility.git
cd wifi-failover-utility
pip install -e .

# Run tests
pytest

# Build distribution
python setup.py sdist bdist_wheel

License

MIT License - See LICENSE file for details

Contributing

Contributions welcome! Please:

1. Fork the repository
2. Create a feature branch
3. Submit a pull request

Support

For issues, questions, or suggestions:

• Open a GitHub issue
• Check Troubleshooting section
• Review CLOUDFLARE_SETUP.md for Worker deployment