Attempt to add OnDelete:CASCADE to sqlite

Signed-off-by: Gabriel Adrian Samfira <gsamfira@cloudbasesolutions.com>

database/sql/sql.go

@@ -16,7 +16,9 @@ package sql
 
 import (
 	"context"
+	"fmt"
 	"log"
+	"strings"
 
 	"github.com/pkg/errors"
 	"gorm.io/driver/mysql"
@@ -79,6 +81,111 @@ type sqlDatabase struct {
 	cfg  config.Database
 }
 
+var renameTemplate = `
+PRAGMA foreign_keys = OFF;
+BEGIN TRANSACTION;
+
+ALTER TABLE %s RENAME TO %s_old;
+COMMIT;
+`
+
+var restoreNameTemplate = `
+PRAGMA foreign_keys = OFF;
+BEGIN TRANSACTION;
+DROP TABLE IF EXISTS %s;
+ALTER TABLE %s_old RENAME TO %s;
+COMMIT;
+`
+
+var copyContentsTemplate = `
+PRAGMA foreign_keys = OFF;
+BEGIN TRANSACTION;
+INSERT INTO %s SELECT * FROM %s_old;
+DROP TABLE %s_old;
+
+COMMIT;
+`
+
+func (s *sqlDatabase) cascadeMigrationSQLite(model interface{}, name string, justDrop bool) error {
+	if !s.conn.Migrator().HasTable(name) {
+		return nil
+	}
+	defer s.conn.Exec("PRAGMA foreign_keys = ON;")
+
+	var data string
+	var indexes []string
+	if err := s.conn.Raw(fmt.Sprintf("select sql from sqlite_master where tbl_name='%s' and name='%s'", name, name)).Scan(&data).Error; err != nil {
+		if !errors.Is(err, gorm.ErrRecordNotFound) {
+			return fmt.Errorf("failed to get table %s: %w", name, err)
+		}
+	}
+
+	if err := s.conn.Raw(fmt.Sprintf("SELECT name FROM sqlite_master WHERE type == 'index' AND tbl_name == '%s' and name not like 'sqlite_%%'", name)).Scan(&indexes).Error; err != nil {
+		if !errors.Is(err, gorm.ErrRecordNotFound) {
+			return fmt.Errorf("failed to get table indexes %s: %w", name, err)
+		}
+	}
+
+	if strings.Contains(data, "ON DELETE CASCADE") {
+		return nil
+	}
+
+	if justDrop {
+		if err := s.conn.Migrator().DropTable(model); err != nil {
+			return fmt.Errorf("failed to drop table %s: %w", name, err)
+		}
+		return nil
+	}
+
+	for _, index := range indexes {
+		if err := s.conn.Migrator().DropIndex(model, index); err != nil {
+			return fmt.Errorf("failed to drop index %s: %w", index, err)
+		}
+	}
+
+	err := s.conn.Exec(fmt.Sprintf(renameTemplate, name, name)).Error
+	if err != nil {
+		return fmt.Errorf("failed to rename table %s: %w", name, err)
+	}
+
+	if model != nil {
+		if err := s.conn.Migrator().AutoMigrate(model); err != nil {
+			if err := s.conn.Exec(fmt.Sprintf(restoreNameTemplate, name, name, name)).Error; err != nil {
+				log.Printf("failed to restore table %s: %s", name, err)
+			}
+			return fmt.Errorf("failed to create table %s: %w", name, err)
+		}
+	}
+	err = s.conn.Exec(fmt.Sprintf(copyContentsTemplate, name, name, name)).Error
+	if err != nil {
+		return fmt.Errorf("failed to copy contents to table %s: %w", name, err)
+	}
+
+	return nil
+}
+
+func (s *sqlDatabase) cascadeMigration() error {
+	switch s.cfg.DbBackend {
+	case config.SQLiteBackend:
+		if err := s.cascadeMigrationSQLite(&Address{}, "addresses", true); err != nil {
+			return fmt.Errorf("failed to drop table addresses: %w", err)
+		}
+
+		if err := s.cascadeMigrationSQLite(&InstanceStatusUpdate{}, "instance_status_updates", true); err != nil {
+			return fmt.Errorf("failed to drop table instance_status_updates: %w", err)
+		}
+
+		if err := s.cascadeMigrationSQLite(&Tag{}, "pool_tags", false); err != nil {
+			return fmt.Errorf("failed to migrate addresses: %w", err)
+		}
+	case config.MySQLBackend:
+		return nil
+	default:
+		return fmt.Errorf("invalid db backend: %s", s.cfg.DbBackend)
+	}
+	return nil
+}
+
 func (s *sqlDatabase) migrateDB() error {
 	if s.conn.Migrator().HasIndex(&Organization{}, "idx_organizations_name") {
 		if err := s.conn.Migrator().DropIndex(&Organization{}, "idx_organizations_name"); err != nil {
@@ -91,6 +198,11 @@ func (s *sqlDatabase) migrateDB() error {
 			log.Printf("failed to drop index idx_owner: %s", err)
 		}
 	}
+
+	if err := s.cascadeMigration(); err != nil {
+		return errors.Wrap(err, "running cascade migration")
+	}
+
 	if err := s.conn.AutoMigrate(
 		&Tag{},
 		&Pool{},