Bitcoin Silver Notification Backend

Push notification backend server for Bitcoin Silver wallet.

Prerequisites

• Bitcoin Silver node running with ZMQ enabled
• PostgreSQL database
• Redis (optional, for future enhancements)
• Node.js v18 or higher
• Firebase project with Admin SDK service account

Installation

1. Upload to VPS

# On your local machine, from the wallet directory:
scp -r backend btcwallet@YOUR_VPS_IP:~/btcs-notification-backend

# Or use rsync:
rsync -avz backend/ btcwallet@YOUR_VPS_IP:~/btcs-notification-backend/

2. Install Dependencies on VPS

ssh btcwallet@YOUR_VPS_IP
cd ~/btcs-notification-backend
npm install

3. Create Database

# Create database and user
sudo -u postgres psql << EOF
CREATE DATABASE btcs_notifications;
CREATE USER btcs_backend WITH PASSWORD 'YOUR_SECURE_PASSWORD';
GRANT ALL PRIVILEGES ON DATABASE btcs_notifications TO btcs_backend;
\q
EOF

# Create tables
PGPASSWORD='YOUR_SECURE_PASSWORD' psql -U btcs_backend -d btcs_notifications -h localhost << 'EOF'
CREATE TABLE device_tokens (
    id SERIAL PRIMARY KEY,
    address VARCHAR(100) NOT NULL,
    device_token TEXT NOT NULL,
    platform VARCHAR(10) DEFAULT 'android',
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    last_active TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    UNIQUE(address, device_token)
);

CREATE INDEX idx_address ON device_tokens(address);

CREATE TABLE notifications (
    id SERIAL PRIMARY KEY,
    address VARCHAR(100) NOT NULL,
    txid VARCHAR(64) NOT NULL,
    amount DECIMAL(16,8) NOT NULL,
    sent BOOLEAN DEFAULT FALSE,
    confirmed BOOLEAN DEFAULT FALSE,
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    UNIQUE(address, txid)
);
\q
EOF

4. Configure Firebase Admin SDK

1. Go to Firebase Console
2. Select your project (or create one)
3. Go to Project Settings → Service Accounts
4. Click Generate new private key
5. Save the downloaded JSON file as firebase-admin-key.json in the project root

# Upload the key file to VPS
scp firebase-admin-key.json btcwallet@YOUR_VPS_IP:~/btcs-notification-backend/

5. Configure Environment

cd ~/btcs-notification-backend
cp .env.example .env
nano .env

Update these values in .env:

• DB_PASSWORD - Your PostgreSQL password
• API_KEY - A secure random string for API authentication
• LIVECOINWATCH_API_KEY - Your LiveCoinWatch API key (for price monitoring)

6. Test the Backend

# Test run
npm start

# In another terminal, test the health endpoint
curl http://localhost:3000/health

Running in Production

Option 1: Using PM2 (Recommended)

npm install -g pm2

# Start the backend
pm2 start src/server.js --name btcs-backend

# Save PM2 configuration
pm2 save

# Setup auto-start on boot
pm2 startup

# Monitor
pm2 status
pm2 logs btcs-backend
pm2 monit

Option 2: Using systemd

Create /etc/systemd/system/btcs-backend.service:

[Unit]
Description=Bitcoin Silver Notification Backend
After=network.target postgresql.service

[Service]
Type=simple
User=btcwallet
WorkingDirectory=/home/btcwallet/btcs-notification-backend
ExecStart=/usr/bin/node src/server.js
Restart=always
RestartSec=10
StandardOutput=journal
StandardError=journal

[Install]
WantedBy=multi-user.target

Enable and start:

sudo systemctl daemon-reload
sudo systemctl enable btcs-backend
sudo systemctl start btcs-backend
sudo systemctl status btcs-backend

# View logs
journalctl -u btcs-backend -f

API Endpoints

Health Check

GET /health

Register Device

POST /api/register
Content-Type: application/json

{
  "address": "btcs1q...",
  "device_token": "fcm_token...",
  "platform": "android"
}

Unregister Device

POST /api/unregister
Content-Type: application/json

{
  "address": "btcs1q...",
  "device_token": "fcm_token..."
}

Get Notification History

GET /api/notifications/:address?limit=50

Get Statistics

GET /api/stats

Test Notification

POST /api/test-notification
Content-Type: application/json

{
  "device_token": "fcm_token..."
}

Firewall Configuration

sudo ufw allow 22/tcp      # SSH
sudo ufw allow 3000/tcp    # API (or use nginx reverse proxy)
sudo ufw enable

Monitoring

Check Logs

# PM2
pm2 logs btcs-backend

# systemd
journalctl -u btcs-backend -f

# Log files
tail -f combined.log
tail -f error.log

Check Database

psql -U btcs_backend -d btcs_notifications -h localhost

# Inside psql:
SELECT * FROM device_tokens;
SELECT * FROM notifications ORDER BY created_at DESC LIMIT 10;

Check Bitcoin Node

bitcoinsilver-cli getblockchaininfo

Troubleshooting

Backend won't start

1. Check Bitcoin node is running: bitcoinsilver-cli getblockchaininfo
2. Check database credentials in .env
3. Check logs: pm2 logs btcs-backend or journalctl -u btcs-backend

Notifications not arriving

1. Check firebase-admin-key.json exists in project root
2. Verify Firebase project has Cloud Messaging enabled
3. Check device is registered: Query database
4. Check ZMQ is working: Look for "Processing transaction" in logs

Database connection failed

1. Check PostgreSQL is running: sudo systemctl status postgresql
2. Check database exists: sudo -u postgres psql -l | grep btcs
3. Check credentials in .env

Security Notes

• Never commit .env or firebase-admin-key.json files
• Use strong database passwords
• Keep Firebase service account key secret
• Run behind nginx with SSL in production
• Use firewall to restrict access
• Regular security updates: sudo apt update && sudo apt upgrade

Updating

# On local machine, update code then:
rsync -avz backend/ btcwallet@YOUR_VPS_IP:~/btcs-notification-backend/

# On VPS:
cd ~/btcs-notification-backend
npm install
pm2 restart btcs-backend