# Database Persistence

## Overview

AtlasOS now supports SQLite-based database persistence for configuration and state management. The database layer is optional - if no database path is provided, the system operates in in-memory mode (data is lost on restart).

## Configuration

Set the `ATLAS_DB_PATH` environment variable to enable database persistence:

```bash
export ATLAS_DB_PATH=/var/lib/atlas/atlas.db
./atlas-api
```

If not set, the system defaults to `data/atlas.db` in the current directory.

## Database Schema

The database includes tables for:

- **users** - User accounts and authentication
- **audit_logs** - Audit trail with indexes for efficient querying
- **smb_shares** - SMB/CIFS share configurations
- **nfs_exports** - NFS export configurations
- **iscsi_targets** - iSCSI target configurations
- **iscsi_luns** - iSCSI LUN mappings
- **snapshot_policies** - Automated snapshot policies

## Current Status

✅ **Database Infrastructure**: Complete
- SQLite database connection and migration system
- Schema definitions for all entities
- Optional database mode (falls back to in-memory if not configured)

⏳ **Store Migration**: In Progress
- Stores currently use in-memory implementations
- Database-backed implementations can be added incrementally
- Pattern established for migration

## Migration Pattern

To migrate a store to use the database:

1. Add database field to store struct
2. Update `New*Store()` to accept `*db.DB` parameter
3. Implement database queries in CRUD methods
4. Update `app.go` to pass database to store constructor

Example pattern:

```go
type UserStore struct {
    db   *db.DB
    mu   sync.RWMutex
    // ... other fields
}

func NewUserStore(db *db.DB, auth *Service) *UserStore {
    // Initialize with database
}

func (s *UserStore) Create(...) (*User, error) {
    // Use database instead of in-memory map
    _, err := s.db.Exec("INSERT INTO users ...")
    // ...
}
```

## Benefits

- **Persistence**: Configuration survives restarts
- **Audit Trail**: Historical audit logs preserved
- **Scalability**: Can migrate to PostgreSQL/MySQL later
- **Backup**: Simple file-based backup (SQLite database file)

## Next Steps

1. Migrate user store to database (highest priority for security)
2. Migrate audit log store (for historical tracking)
3. Migrate storage service stores (SMB/NFS/iSCSI)
4. Migrate snapshot policy store
5. Add database backup/restore utilities