Implement SQLite database persistence for instance management

pkg/database/database.go

@@ -0,0 +1,107 @@
+package database
+
+import (
+	"database/sql"
+	"fmt"
+	"llamactl/pkg/instance"
+	"log"
+	"path/filepath"
+	"time"
+
+	_ "github.com/mattn/go-sqlite3"
+)
+
+// Database defines the interface for instance persistence operations
+type Database interface {
+	Save(inst *instance.Instance) error
+	Delete(name string) error
+	LoadAll() ([]*instance.Instance, error)
+	Close() error
+}
+
+// Config contains database configuration settings
+type Config struct {
+	// Database file path (relative to data_dir or absolute)
+	Path string
+
+	// Connection settings
+	MaxOpenConnections int
+	MaxIdleConnections int
+	ConnMaxLifetime    time.Duration
+}
+
+// DB wraps the database connection with configuration
+type DB struct {
+	*sql.DB
+	config *Config
+}
+
+// Open creates a new database connection with the provided configuration
+func Open(config *Config) (*DB, error) {
+	if config == nil {
+		return nil, fmt.Errorf("database config cannot be nil")
+	}
+
+	if config.Path == "" {
+		return nil, fmt.Errorf("database path cannot be empty")
+	}
+
+	// Ensure the database directory exists
+	dbDir := filepath.Dir(config.Path)
+	if dbDir != "." && dbDir != "/" {
+		// Directory will be created by the manager if auto_create_dirs is enabled
+		log.Printf("Database will be created at: %s", config.Path)
+	}
+
+	// Open SQLite database with proper options
+	// - _journal_mode=WAL: Write-Ahead Logging for better concurrency
+	// - _busy_timeout=5000: Wait up to 5 seconds if database is locked
+	// - _foreign_keys=1: Enable foreign key constraints (for future use)
+	dsn := fmt.Sprintf("file:%s?_journal_mode=WAL&_busy_timeout=5000&_foreign_keys=1", config.Path)
+
+	sqlDB, err := sql.Open("sqlite3", dsn)
+	if err != nil {
+		return nil, fmt.Errorf("failed to open database: %w", err)
+	}
+
+	// Configure connection pool
+	if config.MaxOpenConnections > 0 {
+		sqlDB.SetMaxOpenConns(config.MaxOpenConnections)
+	}
+	if config.MaxIdleConnections > 0 {
+		sqlDB.SetMaxIdleConns(config.MaxIdleConnections)
+	}
+	if config.ConnMaxLifetime > 0 {
+		sqlDB.SetConnMaxLifetime(config.ConnMaxLifetime)
+	}
+
+	// Verify database connection
+	if err := sqlDB.Ping(); err != nil {
+		sqlDB.Close()
+		return nil, fmt.Errorf("failed to ping database: %w", err)
+	}
+
+	log.Printf("Database connection established: %s", config.Path)
+
+	return &DB{
+		DB:     sqlDB,
+		config: config,
+	}, nil
+}
+
+// Close closes the database connection
+func (db *DB) Close() error {
+	if db.DB != nil {
+		log.Println("Closing database connection")
+		return db.DB.Close()
+	}
+	return nil
+}
+
+// HealthCheck verifies the database is accessible
+func (db *DB) HealthCheck() error {
+	if db.DB == nil {
+		return fmt.Errorf("database connection is nil")
+	}
+	return db.DB.Ping()
+}