feat(deploy): 在线更新 - 新增后台检查、强制备份迁移与失败自动回退

backend/internal/database/migrations.go

@@ -0,0 +1,133 @@
+package database
+
+import (
+	"errors"
+	"fmt"
+	"time"
+
+	"gorm.io/gorm"
+)
+
+const CurrentSchemaVersion int64 = 1
+
+const baselineSchemaChecksum = "sha256:open-ai-canvas-schema-v1-20260830"
+
+const postgresSchemaMigrationLockID int64 = 73123910420260830
+
+type SchemaStatus struct {
+	Current  int64 `json:"current"`
+	Expected int64 `json:"expected"`
+	Ready    bool  `json:"ready"`
+}
+
+type schemaMigration struct {
+	Version   int64     `gorm:"primaryKey"`
+	Name      string    `gorm:"size:160;not null"`
+	Checksum  string    `gorm:"size:96;not null"`
+	AppliedAt time.Time `gorm:"not null"`
+}
+
+func (schemaMigration) TableName() string { return "schema_migrations" }
+
+type migration struct {
+	version  int64
+	name     string
+	checksum string
+	apply    func(*gorm.DB) error
+}
+
+var schemaMigrations = []migration{
+	{version: 1, name: "baseline_gorm_schema", checksum: baselineSchemaChecksum, apply: migrateSchemaV1},
+}
+
+func MigrateSchema(db *gorm.DB) error {
+	return db.Transaction(func(tx *gorm.DB) error {
+		if tx.Dialector.Name() == "postgres" {
+			if err := tx.Exec("SELECT pg_advisory_xact_lock(?)", postgresSchemaMigrationLockID).Error; err != nil {
+				return fmt.Errorf("获取数据库迁移锁：%w", err)
+			}
+		}
+		if err := tx.AutoMigrate(&schemaMigration{}); err != nil {
+			return fmt.Errorf("初始化数据库迁移记录：%w", err)
+		}
+		for _, item := range schemaMigrations {
+			var applied schemaMigration
+			err := tx.First(&applied, "version = ?", item.version).Error
+			if err == nil {
+				if err := validateMigrationRecord(applied, item); err != nil {
+					return err
+				}
+				continue
+			}
+			if !errors.Is(err, gorm.ErrRecordNotFound) {
+				return fmt.Errorf("读取数据库迁移 %d：%w", item.version, err)
+			}
+			if err := item.apply(tx); err != nil {
+				return fmt.Errorf("执行数据库迁移 %d（%s）：%w", item.version, item.name, err)
+			}
+			record := schemaMigration{Version: item.version, Name: item.name, Checksum: item.checksum, AppliedAt: time.Now().UTC()}
+			if err := tx.Create(&record).Error; err != nil {
+				return fmt.Errorf("记录数据库迁移 %d：%w", item.version, err)
+			}
+		}
+		return RequireSchemaVersion(tx)
+	})
+}
+
+func ReadSchemaStatus(db *gorm.DB) (SchemaStatus, error) {
+	status := SchemaStatus{Expected: CurrentSchemaVersion}
+	if !db.Migrator().HasTable(&schemaMigration{}) {
+		return status, nil
+	}
+	if err := db.Model(&schemaMigration{}).Select("COALESCE(MAX(version), 0)").Scan(&status.Current).Error; err != nil {
+		return status, fmt.Errorf("读取数据库结构版本：%w", err)
+	}
+	if status.Current != status.Expected {
+		return status, nil
+	}
+	if err := validateMigrationRecords(db); err != nil {
+		return status, err
+	}
+	status.Ready = true
+	return status, nil
+}
+
+func validateMigrationRecords(db *gorm.DB) error {
+	for _, item := range schemaMigrations {
+		var applied schemaMigration
+		if err := db.First(&applied, "version = ?", item.version).Error; err != nil {
+			if errors.Is(err, gorm.ErrRecordNotFound) {
+				return fmt.Errorf("数据库缺少迁移记录 %d（%s）", item.version, item.name)
+			}
+			return fmt.Errorf("读取数据库迁移 %d：%w", item.version, err)
+		}
+		if err := validateMigrationRecord(applied, item); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func validateMigrationRecord(applied schemaMigration, expected migration) error {
+	if applied.Name != expected.name {
+		return fmt.Errorf("数据库迁移 %d 名称不一致：记录为 %s，程序期望 %s", expected.version, applied.Name, expected.name)
+	}
+	if applied.Checksum != expected.checksum {
+		return fmt.Errorf("数据库迁移 %d 校验和不一致：记录为 %s，程序期望 %s", expected.version, applied.Checksum, expected.checksum)
+	}
+	return nil
+}
+
+func RequireSchemaVersion(db *gorm.DB) error {
+	status, err := ReadSchemaStatus(db)
+	if err != nil {
+		return err
+	}
+	if status.Current < status.Expected {
+		return fmt.Errorf("数据库结构版本过旧：当前 %d，程序要求 %d，请先执行 migrate-schema up", status.Current, status.Expected)
+	}
+	if status.Current > status.Expected {
+		return fmt.Errorf("数据库结构版本 %d 高于程序支持的 %d，拒绝使用旧程序连接新数据库", status.Current, status.Expected)
+	}
+	return nil
+}