# Troubleshooting Guide

## Common Issues and Solutions

### Service Startup Issues

#### Gateway Won't Start

**Symptoms:** Container exits immediately or health checks fail

**Diagnostic Steps:**
```bash
# Check container logs
docker-compose -f docker-compose.prod.yml logs gateway

# Check database file
ls -la data/metadata.db

# Test database connection
sqlite3 data/metadata.db "SELECT COUNT(*) FROM files;"
```

**Common Causes & Solutions:**

1. **Database permissions:**
   ```bash
   sudo chown -R $USER:$USER data/
   chmod -R 755 data/
   ```

2. **Port conflicts:**
   ```bash
   # Check what's using port 9876
   sudo netstat -tulpn | grep 9876
   # Kill conflicting process or change port
   ```

3. **Insufficient disk space:**
   ```bash
   df -h
   # Free up space or add storage
   ```

#### Redis Connection Issues

**Symptoms:** Gateway logs show Redis connection errors

**Solutions:**
```bash
# Check Redis container
docker-compose -f docker-compose.prod.yml logs redis

# Test Redis connection
docker exec -it torrentgateway_redis_1 redis-cli ping

# Restart Redis
docker-compose -f docker-compose.prod.yml restart redis
```

### Performance Issues

#### High CPU Usage

**Diagnostic:**
```bash
# Check container resource usage
docker stats

# Check system resources
top
htop
```

**Solutions:**
1. **Scale gateway instances:**
   ```bash
   docker-compose -f docker-compose.prod.yml up -d --scale gateway=2
   ```

2. **Optimize database:**
   ```bash
   ./scripts/migrate.sh  # Runs VACUUM and ANALYZE
   ```

3. **Add resource limits:**
   ```yaml
   services:
     gateway:
       deploy:
         resources:
           limits:
             cpus: '1.0'
             memory: 1G
   ```

#### High Memory Usage

**Diagnostic:**
```bash
# Check memory usage by container
docker stats --format "table {{.Container}}\t{{.CPUPerc}}\t{{.MemUsage}}"

# Check for memory leaks in logs
docker-compose logs gateway | grep -i "memory\|leak\|oom"
```

**Solutions:**
1. **Restart affected containers:**
   ```bash
   docker-compose -f docker-compose.prod.yml restart gateway
   ```

2. **Implement memory limits:**
   ```yaml
   services:
     gateway:
       deploy:
         resources:
           limits:
             memory: 2G
   ```

#### Slow Response Times

**Diagnostic:**
```bash
# Test API response time
curl -w "@curl-format.txt" -o /dev/null -s http://localhost:9876/api/health

# Check database performance
sqlite3 data/metadata.db "EXPLAIN QUERY PLAN SELECT * FROM files LIMIT 10;"
```

**Solutions:**
1. **Add database indexes:**
   ```bash
   ./scripts/migrate.sh  # Applies performance indexes
   ```

2. **Optimize storage:**
   ```bash
   # Check storage I/O
   iostat -x 1 5
   ```

### Database Issues

#### Database Corruption

**Symptoms:** SQLite errors, integrity check failures

**Diagnostic:**
```bash
# Check database integrity
sqlite3 data/metadata.db "PRAGMA integrity_check;"

# Check database size and structure
sqlite3 data/metadata.db ".schema"
ls -lh data/metadata.db
```

**Recovery:**
```bash
# Attempt repair
sqlite3 data/metadata.db "VACUUM;"

# If repair fails, restore from backup
./scripts/restore.sh $(ls backups/ | grep gateway_backup | tail -1 | sed 's/gateway_backup_\(.*\).tar.gz/\1/')
```

#### Database Lock Issues

**Symptoms:** "database is locked" errors

**Solutions:**
```bash
# Find processes using database
lsof data/metadata.db

# Force unlock (dangerous - stop gateway first)
docker-compose -f docker-compose.prod.yml stop gateway
rm -f data/metadata.db-wal data/metadata.db-shm
```

### Storage Issues

#### Disk Space Full

**Diagnostic:**
```bash
# Check disk usage
df -h
du -sh data/*

# Find large files
find data/ -type f -size +100M -exec ls -lh {} \;
```

**Solutions:**
1. **Clean up old files:**
   ```bash
   # Remove files older than 30 days
   find data/blobs/ -type f -mtime +30 -delete
   find data/chunks/ -type f -mtime +30 -delete
   ```

2. **Cleanup orphaned data:**
   ```bash
   ./scripts/migrate.sh  # Removes orphaned chunks
   ```

#### Storage Corruption

**Symptoms:** File integrity check failures

**Diagnostic:**
```bash
# Run E2E tests to verify storage
./test/e2e/run_all_tests.sh

# Check file system
fsck /dev/disk/by-label/data
```

### Network Issues

#### API Timeouts

**Diagnostic:**
```bash
# Test network connectivity
curl -v http://localhost:9876/api/health

# Check Docker network
docker network ls
docker network inspect torrentgateway_default
```

**Solutions:**
```bash
# Restart networking
docker-compose -f docker-compose.prod.yml down
docker-compose -f docker-compose.prod.yml up -d

# Increase timeouts in client
curl --connect-timeout 30 --max-time 60 http://localhost:9876/api/health
```

#### Port Binding Issues

**Symptoms:** "Port already in use" errors

**Diagnostic:**
```bash
# Check port usage
sudo netstat -tulpn | grep :9876
sudo lsof -i :9876
```

**Solutions:**
```bash
# Kill conflicting process
sudo kill $(sudo lsof -t -i:9876)

# Or change port in docker-compose.yml
```

### Monitoring Issues

#### Prometheus Not Scraping

**Diagnostic:**
```bash
# Check Prometheus targets
curl -s http://localhost:9090/api/v1/targets

# Check metrics endpoint
curl -s http://localhost:9876/metrics
```

**Solutions:**
```bash
# Restart Prometheus
docker-compose -f docker-compose.prod.yml restart prometheus

# Check configuration
docker-compose -f docker-compose.prod.yml exec prometheus cat /etc/prometheus/prometheus.yml
```

#### Grafana Dashboard Issues

**Common Problems:**
1. **No data in dashboards:**
   - Check Prometheus data source configuration
   - Verify metrics are being collected

2. **Dashboard import failures:**
   - Check JSON syntax
   - Verify dashboard version compatibility

### Log Analysis

#### Finding Specific Errors

```bash
# Gateway application logs
docker-compose -f docker-compose.prod.yml logs gateway | grep -i error

# System logs with timestamps
docker-compose -f docker-compose.prod.yml logs --timestamps

# Follow logs in real-time
docker-compose -f docker-compose.prod.yml logs -f gateway
```

#### Log Rotation Issues

```bash
# Check log sizes
docker-compose -f docker-compose.prod.yml exec gateway ls -lh /app/logs/

# Manually rotate logs
docker-compose -f docker-compose.prod.yml exec gateway logrotate /etc/logrotate.conf
```

## Emergency Procedures

### Complete Service Failure

1. **Stop all services:**
   ```bash
   docker-compose -f docker-compose.prod.yml down
   ```

2. **Check system resources:**
   ```bash
   df -h
   free -h
   top
   ```

3. **Restore from backup:**
   ```bash
   ./scripts/restore.sh <timestamp>
   ```

### Data Recovery

1. **Create immediate backup:**
   ```bash
   ./scripts/backup.sh emergency
   ```

2. **Assess data integrity:**
   ```bash
   sqlite3 data/metadata.db "PRAGMA integrity_check;"
   ```

3. **Restore if necessary:**
   ```bash
   ./scripts/restore.sh <last_good_backup>
   ```

## Getting Help

### Log Collection

Before reporting issues, collect relevant logs:

```bash
# Create diagnostics package
mkdir -p diagnostics
docker-compose -f docker-compose.prod.yml logs > diagnostics/service_logs.txt
./scripts/health_check.sh > diagnostics/health_check.txt 2>&1
cp data/metadata.db diagnostics/ 2>/dev/null || echo "Database not accessible"
tar -czf diagnostics_$(date +%Y%m%d_%H%M%S).tar.gz diagnostics/
```

### Health Check Output

Always include health check results:
```bash
./scripts/health_check.sh | tee health_status.txt
```

### System Information

```bash
# Collect system info
echo "Docker version: $(docker --version)" > system_info.txt
echo "Docker Compose version: $(docker-compose --version)" >> system_info.txt
echo "System: $(uname -a)" >> system_info.txt
echo "Memory: $(free -h)" >> system_info.txt
echo "Disk: $(df -h)" >> system_info.txt
```