# Deployment Guide

This guide covers deploying the Hasher application to production.

## Prerequisites

- Node.js 18.x or higher
- Redis 6.x or higher
- Domain name (optional, for custom domain)
- SSL certificate (recommended for production)

## Deployment Options

### Option 1: Vercel (Recommended for Next.js)

Vercel provides seamless deployment for Next.js applications.

#### Steps:

1. **Install Vercel CLI**:
   ```bash
   npm install -g vercel
   ```

2. **Login to Vercel**:
   ```bash
   vercel login
   ```

3. **Deploy**:
   ```bash
   vercel
   ```

4. **Set Environment Variables**:
   - Go to your project settings on Vercel
   - Add environment variables:
     - `REDIS_HOST=your-redis-host.com`
     - `REDIS_PORT=6379`
     - `REDIS_PASSWORD=your-secure-password` (if using authentication)
   - Redeploy: `vercel --prod`

#### Important Notes:
- Ensure Redis is accessible from Vercel's servers
- Consider using [Upstash](https://upstash.com) or [Redis Cloud](https://redis.com/try-free/) for managed Redis
- Use environment variables for sensitive configuration

---

### Option 2: Docker

Deploy using Docker containers.

#### Create Dockerfile:

```dockerfile
# Create this file: Dockerfile
FROM node:18-alpine AS base

# Install dependencies only when needed
FROM base AS deps
RUN apk add --no-cache libc6-compat
WORKDIR /app

COPY package.json package-lock.json* ./
RUN npm ci

# Rebuild the source code only when needed
FROM base AS builder
WORKDIR /app
COPY --from=deps /app/node_modules ./node_modules
COPY . .

RUN npm run build

# Production image, copy all the files and run next
FROM base AS runner
WORKDIR /app

ENV NODE_ENV production

RUN addgroup --system --gid 1001 nodejs
RUN adduser --system --uid 1001 nextjs

COPY --from=builder /app/public ./public
COPY --from=builder --chown=nextjs:nodejs /app/.next/standalone ./
COPY --from=builder --chown=nextjs:nodejs /app/.next/static ./.next/static

USER nextjs

EXPOSE 3000

ENV PORT 3000

CMD ["node", "server.js"]
```

#### Build and Run:

```bash
# Build the Docker image
docker build -t hasher:latest .

# Run the container
docker run -d \
  -p 3000:3000 \
  -e REDIS_HOST=redis \
  -e REDIS_PORT=6379 \
  -e REDIS_PASSWORD=your-password \
  --name hasher \
  hasher:latest
```

#### Docker Compose:

Create `docker-compose.yml`:

```yaml
version: '3.8'

services:
  app:
    build: .
    ports:
      - "3000:3000"
    environment:
      - REDIS_HOST=redis
      - REDIS_PORT=6379
      - REDIS_PASSWORD=your-secure-password
    depends_on:
      - redis
    restart: unless-stopped

  redis:
    image: redis:7-alpine
    command: redis-server --requirepass your-secure-password --appendonly yes
    ports:
      - "6379:6379"
    volumes:
      - redis-data:/data
    restart: unless-stopped

volumes:
  redis-data:
```

Run with:
```bash
docker-compose up -d
```

---

### Option 3: Traditional VPS (Ubuntu/Debian)

Deploy to a traditional server.

#### 1. Install Node.js:

```bash
curl -fsSL https://deb.nodesource.com/setup_18.x | sudo -E bash -
sudo apt-get install -y nodejs
```

#### 2. Install Redis:

```bash
sudo apt-get update
sudo apt-get install redis-server

# Configure Redis
sudo nano /etc/redis/redis.conf
# Set: requirepass your-strong-password

# Start Redis
sudo systemctl start redis-server
sudo systemctl enable redis-server
```

#### 3. Install PM2 (Process Manager):

```bash
sudo npm install -g pm2
```

#### 4. Clone and Build:

```bash
cd /var/www
git clone <your-repo-url> hasher
cd hasher
npm install
npm run build
```

#### 5. Configure Environment:

```bash
cat > .env.local << EOF
REDIS_HOST=localhost
REDIS_PORT=6379
REDIS_PASSWORD=your-strong-password
NODE_ENV=production
EOF
```

#### 6. Start with PM2:

```bash
pm2 start npm --name "hasher" -- start
pm2 save
pm2 startup
```

#### 7. Configure Nginx (Optional):

```nginx
server {
    listen 80;
    server_name your-domain.com;

    location / {
        proxy_pass http://localhost:3000;
        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection 'upgrade';
        proxy_set_header Host $host;
        proxy_cache_bypass $http_upgrade;
    }
}
```

Enable the site:
```bash
sudo ln -s /etc/nginx/sites-available/hasher /etc/nginx/sites-enabled/
sudo nginx -t
sudo systemctl reload nginx
```

---

## Redis Setup

### Option 1: Managed Redis (Recommended)

#### Upstash (Serverless Redis)
1. Sign up at [Upstash](https://upstash.com)
2. Create a database
3. Copy connection details
4. Update environment variables

#### Redis Cloud
1. Sign up at [Redis Cloud](https://redis.com/try-free/)
2. Create a database
3. Note the endpoint and password
4. Update `REDIS_HOST`, `REDIS_PORT`, and `REDIS_PASSWORD`

### Option 2: Self-Hosted Redis

```bash
# Ubuntu/Debian
sudo apt-get update
sudo apt-get install redis-server

# Configure Redis security
sudo nano /etc/redis/redis.conf

# Important settings:
# bind 127.0.0.1 ::1  # Only local connections (remove for remote)
# requirepass your-strong-password
# maxmemory 256mb
# maxmemory-policy allkeys-lru

# Start Redis
sudo systemctl start redis-server
sudo systemctl enable redis-server

# Test connection
redis-cli -a your-strong-password ping
```

---

## Security Considerations

### 1. Redis Security

- **Always** use a strong password with `requirepass`
- Bind Redis to localhost if possible (`bind 127.0.0.1`)
- Use TLS/SSL for remote connections (Redis 6+)
- Disable dangerous commands:
  ```
  rename-command FLUSHDB ""
  rename-command FLUSHALL ""
  rename-command CONFIG ""
  ```
- Set memory limits to prevent OOM

### 2. Application Security

- Use environment variables for secrets
- Enable HTTPS (SSL/TLS)
- Implement rate limiting
- Add CORS restrictions
- Monitor logs for suspicious activity

### 3. Network Security

```bash
# Example UFW firewall rules
sudo ufw allow 80/tcp
sudo ufw allow 443/tcp
sudo ufw allow from YOUR_IP to any port 6379  # Redis (if remote)
sudo ufw enable
```

---

## Monitoring

### Application Monitoring

```bash
# PM2 monitoring
pm2 monit

# View logs
pm2 logs hasher
```

### Redis Monitoring

```bash
# Test connection
redis-cli ping

# Get server info
redis-cli INFO

# Monitor commands
redis-cli MONITOR

# Check memory usage
redis-cli INFO memory

# Check stats
redis-cli INFO stats
```

---

## Backup and Recovery

### Redis Persistence

Redis offers two persistence options:

#### RDB (Redis Database Backup)
```bash
# Configure in redis.conf
save 900 1      # Save if 1 key changed in 15 minutes
save 300 10     # Save if 10 keys changed in 5 minutes
save 60 10000   # Save if 10000 keys changed in 1 minute

# Manual snapshot
redis-cli SAVE

# Backup file location
/var/lib/redis/dump.rdb
```

#### AOF (Append Only File)
```bash
# Enable in redis.conf
appendonly yes
appendfilename "appendonly.aof"

# Sync options
appendfsync everysec  # Good balance

# Backup file location
/var/lib/redis/appendonly.aof
```

### Backup Script

```bash
#!/bin/bash
# backup-redis.sh

BACKUP_DIR="/backup/redis"
DATE=$(date +%Y%m%d_%H%M%S)

# Create backup directory
mkdir -p $BACKUP_DIR

# Trigger Redis save
redis-cli -a your-password SAVE

# Copy RDB file
cp /var/lib/redis/dump.rdb $BACKUP_DIR/dump_$DATE.rdb

# Keep only last 7 days
find $BACKUP_DIR -name "dump_*.rdb" -mtime +7 -delete

echo "Backup completed: dump_$DATE.rdb"
```

### Restore from Backup

```bash
# Stop Redis
sudo systemctl stop redis-server

# Replace dump file
sudo cp /backup/redis/dump_YYYYMMDD_HHMMSS.rdb /var/lib/redis/dump.rdb
sudo chown redis:redis /var/lib/redis/dump.rdb

# Start Redis
sudo systemctl start redis-server
```

---

## Scaling

### Horizontal Scaling

1. Deploy multiple Next.js instances
2. Use a load balancer (nginx, HAProxy, Cloudflare)
3. Share the same Redis instance

### Redis Scaling Options

#### 1. Redis Cluster
- Automatic sharding across multiple nodes
- High availability with automatic failover
- Good for very large datasets

#### 2. Redis Sentinel
- High availability without sharding
- Automatic failover
- Monitoring and notifications

#### 3. Read Replicas
- Separate read and write operations
- Scale read capacity

---

## Troubleshooting

### Check Application Status

```bash
pm2 status
pm2 logs hasher --lines 100
```

### Check Redis

```bash
# Test connection
redis-cli ping

# Check memory
redis-cli INFO memory

# Count keys
redis-cli DBSIZE

# Get stats
redis-cli INFO stats
```

### Common Issues

**Issue**: Cannot connect to Redis
- Check if Redis is running: `sudo systemctl status redis-server`
- Verify firewall rules
- Check `REDIS_HOST` and `REDIS_PORT` environment variables
- Verify password is correct

**Issue**: Out of memory
- Increase Node.js memory: `NODE_OPTIONS=--max-old-space-size=4096`
- Configure Redis maxmemory
- Set appropriate eviction policy

**Issue**: Slow searches
- Check Redis memory usage
- Verify O(1) key lookups are being used
- Monitor Redis with `redis-cli MONITOR`
- Consider Redis Cluster for very large datasets

---

## Performance Optimization

1. **Enable Next.js Static Optimization**
2. **Use CDN for static assets**
3. **Configure Redis pipelining** (already implemented)
4. **Set appropriate maxmemory and eviction policy**
5. **Use SSD storage for Redis persistence**
6. **Enable connection pooling** (already implemented)
7. **Monitor and optimize Redis memory usage**

---

## Environment Variables

| Variable | Description | Default | Required |
|----------|-------------|---------|----------|
| `REDIS_HOST` | Redis server hostname | `localhost` | No |
| `REDIS_PORT` | Redis server port | `6379` | No |
| `REDIS_PASSWORD` | Redis authentication password | - | No* |
| `NODE_ENV` | Node environment | `development` | No |
| `PORT` | Application port | `3000` | No |

*Required if Redis has authentication enabled

---

## Support

For deployment issues, check:
- [Next.js Deployment Docs](https://nextjs.org/docs/deployment)
- [Redis Documentation](https://redis.io/docs/)
- [Upstash Documentation](https://docs.upstash.com/)
- Project GitHub Issues

---

## Deployment Checklist

Before going live:

- [ ] Redis is secured with password
- [ ] Environment variables are configured
- [ ] SSL/TLS certificates are installed
- [ ] Firewall rules are configured
- [ ] Monitoring is set up
- [ ] Backup strategy is in place
- [ ] Load testing completed
- [ ] Error logging configured
- [ ] Redis persistence (RDB/AOF) configured
- [ ] Rate limiting implemented (if needed)
- [ ] Documentation is up to date

---

**Ready to deploy! 🚀**