支持迁移对象存储到 OSS

backend/internal/modules/file/storage.go

@@ -1,6 +1,7 @@
 package file
 
 import (
+	"bytes"
 	"context"
 	"crypto/rand"
 	"encoding/hex"
@@ -24,6 +25,8 @@ type Storage struct {
 	bucket      string
 	bucketMu    sync.Mutex
 	bucketReady bool
+	mirror      *Storage
+	mirrorErr   error
 }
 
 type Object struct {
@@ -33,14 +36,7 @@ type Object struct {
 }
 
 func NewStorage(cfg config.StorageConfig) (*Storage, error) {
-	endpoint, secure, err := normalizeEndpoint(cfg.Endpoint)
-	if err != nil {
-		return nil, err
-	}
-	client, err := minio.New(endpoint, &minio.Options{
-		Creds:  credentials.NewStaticV4(cfg.AccessKeyID, cfg.SecretAccessKey, ""),
-		Secure: secure,
-	})
+	client, err := NewStorageClient(cfg)
 	if err != nil {
 		return nil, err
 	}
@@ -51,6 +47,43 @@ func NewStorage(cfg config.StorageConfig) (*Storage, error) {
 	return storage, nil
 }
 
+// NewStorageClient 根据项目存储配置创建 S3 兼容客户端，供迁移工具复用。
+func NewStorageClient(cfg config.StorageConfig) (*minio.Client, error) {
+	endpoint, secure, err := normalizeEndpoint(cfg.Endpoint)
+	if err != nil {
+		return nil, err
+	}
+	lookup, err := parseBucketLookup(cfg.BucketLookup)
+	if err != nil {
+		return nil, err
+	}
+	return minio.New(endpoint, &minio.Options{
+		Creds:        credentials.NewStaticV4(cfg.AccessKeyID, cfg.SecretAccessKey, ""),
+		Secure:       secure,
+		Region:       cfg.Region,
+		BucketLookup: lookup,
+	})
+}
+
+func parseBucketLookup(raw string) (minio.BucketLookupType, error) {
+	switch strings.ToLower(strings.TrimSpace(raw)) {
+	case "", "auto":
+		return minio.BucketLookupAuto, nil
+	case "dns":
+		return minio.BucketLookupDNS, nil
+	case "path":
+		return minio.BucketLookupPath, nil
+	default:
+		return minio.BucketLookupAuto, fmt.Errorf("unsupported storage bucket lookup: %s", raw)
+	}
+}
+
+// SetMirror 启用迁移期间的同步双写。镜像端不可用时上传会失败，避免出现未同步的业务文件。
+func (s *Storage) SetMirror(mirror *Storage, err error) {
+	s.mirror = mirror
+	s.mirrorErr = err
+}
+
 func (s *Storage) Put(ctx context.Context, scene string, header *multipart.FileHeader, reader io.Reader, contentType string) (string, error) {
 	key, err := newObjectKey(scene, header.Filename)
 	if err != nil {
@@ -65,6 +98,28 @@ func (s *Storage) Put(ctx context.Context, scene string, header *multipart.FileH
 }
 
 func (s *Storage) PutObject(ctx context.Context, key string, reader io.Reader, size int64, contentType string, metadata map[string]string) error {
+	if s.mirrorErr != nil {
+		return fmt.Errorf("storage mirror unavailable: %w", s.mirrorErr)
+	}
+	if s.mirror == nil {
+		return s.putObject(ctx, key, reader, size, contentType, metadata)
+	}
+
+	// 当前文件上传大小被限制在 10MB；镜像写入前缓存在内存中，确保两个端点得到完全相同的字节流。
+	data, err := io.ReadAll(reader)
+	if err != nil {
+		return err
+	}
+	if err := s.putObject(ctx, key, bytes.NewReader(data), int64(len(data)), contentType, metadata); err != nil {
+		return err
+	}
+	if err := s.mirror.putObject(ctx, key, bytes.NewReader(data), int64(len(data)), contentType, metadata); err != nil {
+		return fmt.Errorf("storage mirror upload failed: %w", err)
+	}
+	return nil
+}
+
+func (s *Storage) putObject(ctx context.Context, key string, reader io.Reader, size int64, contentType string, metadata map[string]string) error {
 	if err := s.ensureBucketReady(ctx); err != nil {
 		return err
 	}

backend/internal/modules/file/storage_test.go

@@ -3,6 +3,8 @@ package file
 import (
 	"strings"
 	"testing"
+
+	"github.com/minio/minio-go/v7"
 )
 
 func TestSanitizeObjectMetadataEscapesNonASCII(t *testing.T) {
@@ -15,6 +17,29 @@ func TestSanitizeObjectMetadataEscapesNonASCII(t *testing.T) {
 	}
 }
 
+func TestParseBucketLookup(t *testing.T) {
+	tests := []struct {
+		name string
+		raw  string
+		want minio.BucketLookupType
+	}{
+		{name: "auto", raw: "auto", want: minio.BucketLookupAuto},
+		{name: "dns", raw: "dns", want: minio.BucketLookupDNS},
+		{name: "path", raw: "path", want: minio.BucketLookupPath},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := parseBucketLookup(tt.raw)
+			if err != nil || got != tt.want {
+				t.Fatalf("parseBucketLookup(%q) = %v, %v", tt.raw, got, err)
+			}
+		})
+	}
+	if _, err := parseBucketLookup("invalid"); err == nil {
+		t.Fatal("invalid bucket lookup should fail")
+	}
+}
+
 func TestAnnouncementSceneUsesPublicFileURL(t *testing.T) {
 	key := "announcement/2026/06/15/example.webp"
 	got := fileURLForScene("announcement", key)