add s3 replication sink

8 files changed, 369 insertions, 46 deletions

diff --git a/weed/command/filer_replication.go b/weed/command/filer_replication.go
index b19597245..5e41cbb55 100644
--- a/weed/command/filer_replication.go
+++ b/weed/command/filer_replication.go
@@ -6,6 +6,7 @@ import (
 	"github.com/chrislusf/seaweedfs/weed/server"
 	"github.com/spf13/viper"
 	"strings"
+	"github.com/chrislusf/seaweedfs/weed/replication/sink"
 )
 
 func init() {
@@ -57,7 +58,21 @@ func runFilerReplicate(cmd *Command, args []string) bool {
 		}
 	}
 
-	replicator := replication.NewReplicator(config.Sub("source.filer"), config.Sub("sink.filer"))
+	var dataSink sink.ReplicationSink
+	for _, sk := range sink.Sinks {
+		if config.GetBool("sink." + sk.GetName() + ".enabled") {
+			viperSub := config.Sub("sink." + sk.GetName())
+			if err := sk.Initialize(viperSub); err != nil {
+				glog.Fatalf("Failed to initialize sink for %s: %+v",
+					sk.GetName(), err)
+			}
+			glog.V(0).Infof("Configure sink to %s", sk.GetName())
+			dataSink = sk
+			break
+		}
+	}
+
+	replicator := replication.NewReplicator(config.Sub("source.filer"), dataSink)
 
 	for {
 		key, m, err := notificationInput.ReceiveMessage()
diff --git a/weed/command/scaffold.go b/weed/command/scaffold.go
index 321b50424..e0bd48c8c 100644
--- a/weed/command/scaffold.go
+++ b/weed/command/scaffold.go
@@ -161,7 +161,7 @@ grpcAddress = "localhost:18888"
 directory = "/buckets"    # all files under this directory tree are replicated
 
 [notification.kafka]
-enabled = true
+enabled = false
 hosts = [
   "localhost:9092"
 ]
@@ -170,12 +170,22 @@ offsetFile = "./last.offset"
 offsetSaveIntervalSeconds = 10
 
 [sink.filer]
-enabled = true
+enabled = false
 grpcAddress = "localhost:18888"
 directory = "/backup"    # all replicated files are under this directory tree
 replication = ""
 collection = ""
 ttlSec = 0
 
+[sink.s3]
+# See https://docs.aws.amazon.com/sdk-for-go/v1/developer-guide/sessions.html
+# default loads credentials from the shared credentials file (~/.aws/credentials). 
+enabled = false
+aws_access_key_id     = ""     # if empty, loads from the shared credentials file (~/.aws/credentials).
+aws_secret_access_key = ""     # if empty, loads from the shared credentials file (~/.aws/credentials).
+region = "us-east-2"
+bucket = "your_bucket_name"    # an existing bucket
+directory = ""                 # destination directory (do not prefix or suffix with "/")
+
 `
 )
diff --git a/weed/replication/replicator.go b/weed/replication/replicator.go
index 834da6217..d5a57ecac 100644
--- a/weed/replication/replicator.go
+++ b/weed/replication/replicator.go
@@ -6,8 +6,7 @@ import (
 
 	"github.com/chrislusf/seaweedfs/weed/pb/filer_pb"
 	"github.com/chrislusf/seaweedfs/weed/replication/sink"
-	"github.com/chrislusf/seaweedfs/weed/replication/sink/filersink"
-	"github.com/chrislusf/seaweedfs/weed/replication/source"
+		"github.com/chrislusf/seaweedfs/weed/replication/source"
 	"github.com/chrislusf/seaweedfs/weed/util"
 	"github.com/chrislusf/seaweedfs/weed/glog"
 )
@@ -17,18 +16,15 @@ type Replicator struct {
 	source *source.FilerSource
 }
 
-func NewReplicator(sourceConfig, sinkConfig util.Configuration) *Replicator {
-
-	sink := &filersink.FilerSink{}
-	sink.Initialize(sinkConfig)
+func NewReplicator(sourceConfig util.Configuration, dataSink sink.ReplicationSink) *Replicator {
 
 	source := &source.FilerSource{}
 	source.Initialize(sourceConfig)
 
-	sink.SetSourceFiler(source)
+	dataSink.SetSourceFiler(source)
 
 	return &Replicator{
-		sink:   sink,
+		sink:   dataSink,
 		source: source,
 	}
 }
@@ -39,23 +35,20 @@ func (r *Replicator) Replicate(key string, message *filer_pb.EventNotification)
 	}
 	key = filepath.Join(r.sink.GetSinkToDirectory(), key[len(r.source.Dir):])
 	if message.OldEntry != nil && message.NewEntry == nil {
-		return r.sink.DeleteEntry(key, message.OldEntry, message.DeleteChunks)
+		return r.sink.DeleteEntry(key, message.OldEntry.IsDirectory, message.DeleteChunks)
 	}
 	if message.OldEntry == nil && message.NewEntry != nil {
 		return r.sink.CreateEntry(key, message.NewEntry)
 	}
-	if existingEntry, err := r.sink.LookupEntry(key); err == nil {
-		if message.OldEntry == nil && message.NewEntry == nil {
-			glog.V(0).Infof("message %+v existingEntry: %+v", message, existingEntry)
-			return r.sink.DeleteEntry(key, existingEntry, true)
-		}
-		return r.sink.UpdateEntry(key, message.OldEntry, message.NewEntry, existingEntry, message.DeleteChunks)
-	}
-
-	glog.V(0).Infof("key:%s, message %+v", key, message)
 	if message.OldEntry == nil && message.NewEntry == nil {
+		glog.V(0).Infof("weird message %+v", message)
 		return nil
 	}
 
+	foundExisting, err := r.sink.UpdateEntry(key, message.OldEntry, message.NewEntry, message.DeleteChunks)
+	if foundExisting {
+		return err
+	}
+
 	return r.sink.CreateEntry(key, message.NewEntry)
 }
diff --git a/weed/replication/sink/filersink/filer_sink.go b/weed/replication/sink/filersink/filer_sink.go
index c98c99f34..d526da1c9 100644
--- a/weed/replication/sink/filersink/filer_sink.go
+++ b/weed/replication/sink/filersink/filer_sink.go
@@ -9,6 +9,7 @@ import (
 	"github.com/chrislusf/seaweedfs/weed/pb/filer_pb"
 	"github.com/chrislusf/seaweedfs/weed/replication/source"
 	"github.com/chrislusf/seaweedfs/weed/util"
+	"github.com/chrislusf/seaweedfs/weed/replication/sink"
 )
 
 type FilerSink struct {
@@ -21,6 +22,14 @@ type FilerSink struct {
 	dataCenter  string
 }
 
+func init(){
+	sink.Sinks = append(sink.Sinks, &FilerSink{})
+}
+
+func (fs *FilerSink) GetName() string {
+	return "filer"
+}
+
 func (fs *FilerSink) GetSinkToDirectory() string {
 	return fs.dir
 }
@@ -49,7 +58,7 @@ func (fs *FilerSink) initialize(grpcAddress string, dir string,
 	return nil
 }
 
-func (fs *FilerSink) DeleteEntry(key string, entry *filer_pb.Entry, deleteIncludeChunks bool) error {
+func (fs *FilerSink) DeleteEntry(key string, isDirectory, deleteIncludeChunks bool) error {
 	return fs.withFilerClient(func(client filer_pb.SeaweedFilerClient) error {
 
 		dir, name := filer2.FullPath(key).DirAndName()
@@ -57,7 +66,7 @@ func (fs *FilerSink) DeleteEntry(key string, entry *filer_pb.Entry, deleteInclud
 		request := &filer_pb.DeleteEntryRequest{
 			Directory:    dir,
 			Name:         name,
-			IsDirectory:  entry.IsDirectory,
+			IsDirectory:  isDirectory,
 			IsDeleteData: deleteIncludeChunks,
 		}
 
@@ -121,13 +130,14 @@ func (fs *FilerSink) CreateEntry(key string, entry *filer_pb.Entry) error {
 	})
 }
 
-func (fs *FilerSink) LookupEntry(key string) (entry *filer_pb.Entry, err error) {
+func (fs *FilerSink) UpdateEntry(key string, oldEntry, newEntry *filer_pb.Entry, deleteIncludeChunks bool) (foundExistingEntry bool, err error) {
 
 	ctx := context.Background()
 
 	dir, name := filer2.FullPath(key).DirAndName()
 
 	// read existing entry
+	var existingEntry *filer_pb.Entry
 	err = fs.withFilerClient(func(client filer_pb.SeaweedFilerClient) error {
 
 		request := &filer_pb.LookupDirectoryEntryRequest{
@@ -142,24 +152,15 @@ func (fs *FilerSink) LookupEntry(key string) (entry *filer_pb.Entry, err error)
 			return err
 		}
 
-		entry = resp.Entry
+		existingEntry = resp.Entry
 
 		return nil
 	})
 
 	if err != nil {
-		return nil, fmt.Errorf("lookup %s: %v", key, err)
+		return false, fmt.Errorf("lookup %s: %v", key, err)
 	}
 
-	return entry, nil
-}
-
-func (fs *FilerSink) UpdateEntry(key string, oldEntry, newEntry, existingEntry *filer_pb.Entry, deleteIncludeChunks bool) (err error) {
-
-	ctx := context.Background()
-
-	dir, _ := filer2.FullPath(key).DirAndName()
-
 	glog.V(0).Infof("oldEntry %+v, newEntry %+v, existingEntry: %+v", oldEntry, newEntry, existingEntry)
 
 	if filer2.ETag(newEntry.Chunks) == filer2.ETag(existingEntry.Chunks) {
@@ -179,13 +180,13 @@ func (fs *FilerSink) UpdateEntry(key string, oldEntry, newEntry, existingEntry *
 		// replicate the chunks that are new in the source
 		replicatedChunks, err := fs.replicateChunks(newChunks)
 		if err != nil {
-			return fmt.Errorf("replicte %s chunks error: %v", key, err)
+			return true, fmt.Errorf("replicte %s chunks error: %v", key, err)
 		}
 		existingEntry.Chunks = append(existingEntry.Chunks, replicatedChunks...)
 	}
 
 	// save updated meta data
-	return fs.withFilerClient(func(client filer_pb.SeaweedFilerClient) error {
+	return true, fs.withFilerClient(func(client filer_pb.SeaweedFilerClient) error {
 
 		request := &filer_pb.UpdateEntryRequest{
 			Directory: dir,
diff --git a/weed/replication/sink/replication_sink.go b/weed/replication/sink/replication_sink.go
index c33f3251b..0a86139d3 100644
--- a/weed/replication/sink/replication_sink.go
+++ b/weed/replication/sink/replication_sink.go
@@ -3,13 +3,19 @@ package sink
 import (
 	"github.com/chrislusf/seaweedfs/weed/pb/filer_pb"
 	"github.com/chrislusf/seaweedfs/weed/replication/source"
+	"github.com/chrislusf/seaweedfs/weed/util"
 )
 
 type ReplicationSink interface {
-	DeleteEntry(key string, entry *filer_pb.Entry, deleteIncludeChunks bool) error
+	GetName() string
+	Initialize(configuration util.Configuration) error
+	DeleteEntry(key string, isDirectory, deleteIncludeChunks bool) error
 	CreateEntry(key string, entry *filer_pb.Entry) error
-	UpdateEntry(key string, oldEntry, newEntry, existingEntry *filer_pb.Entry, deleteIncludeChunks bool) error
-	LookupEntry(key string) (entry *filer_pb.Entry, err error)
+	UpdateEntry(key string, oldEntry, newEntry *filer_pb.Entry, deleteIncludeChunks bool) (foundExistingEntry bool, err error)
 	GetSinkToDirectory() string
 	SetSourceFiler(s *source.FilerSource)
 }
+
+var (
+	Sinks []ReplicationSink
+)
diff --git a/weed/replication/sink/s3sink/s3_sink.go b/weed/replication/sink/s3sink/s3_sink.go
new file mode 100644
index 000000000..c8300a108
--- /dev/null
+++ b/weed/replication/sink/s3sink/s3_sink.go
@@ -0,0 +1,123 @@
+package S3Sink
+
+import (
+	"fmt"
+
+	"github.com/chrislusf/seaweedfs/weed/pb/filer_pb"
+	"github.com/chrislusf/seaweedfs/weed/replication/source"
+	"github.com/chrislusf/seaweedfs/weed/util"
+	"github.com/aws/aws-sdk-go/service/s3/s3iface"
+	"github.com/aws/aws-sdk-go/service/s3"
+	"github.com/aws/aws-sdk-go/aws/session"
+	"sync"
+	"github.com/chrislusf/seaweedfs/weed/filer2"
+	"github.com/chrislusf/seaweedfs/weed/replication/sink"
+	"github.com/aws/aws-sdk-go/aws"
+	"github.com/aws/aws-sdk-go/aws/credentials"
+)
+
+type S3Sink struct {
+	err         error
+	conn        s3iface.S3API
+	region      string
+	bucket      string
+	dir         string
+	filerSource *source.FilerSource
+}
+
+func init() {
+	sink.Sinks = append(sink.Sinks, &S3Sink{})
+}
+
+func (s3sink *S3Sink) GetName() string {
+	return "filer"
+}
+
+func (s3sink *S3Sink) GetSinkToDirectory() string {
+	return s3sink.dir
+}
+
+func (s3sink *S3Sink) Initialize(configuration util.Configuration) error {
+	return s3sink.initialize(
+		configuration.GetString("aws_access_key_id"),
+		configuration.GetString("aws_secret_access_key"),
+		configuration.GetString("region"),
+		configuration.GetString("bucket"),
+		configuration.GetString("directory"),
+	)
+}
+
+func (s3sink *S3Sink) SetSourceFiler(s *source.FilerSource) {
+	s3sink.filerSource = s
+}
+
+func (s3sink *S3Sink) initialize(awsAccessKeyId, aswSecretAccessKey, region, bucket, dir string) (error) {
+	s3sink.region = region
+	s3sink.bucket = bucket
+	s3sink.dir = dir
+
+	config := &aws.Config{
+		Region: aws.String(s3sink.region),
+	}
+	if awsAccessKeyId != "" && aswSecretAccessKey != "" {
+		config.Credentials = credentials.NewStaticCredentials(awsAccessKeyId, aswSecretAccessKey, "")
+	}
+
+	sess, err := session.NewSession(config)
+	if err != nil {
+		return fmt.Errorf("create aws session: %v", err)
+	}
+	s3sink.conn = s3.New(sess)
+
+	return nil
+}
+
+func (s3sink *S3Sink) DeleteEntry(key string, isDirectory, deleteIncludeChunks bool) error {
+
+	if isDirectory {
+		key = key + "/"
+	}
+
+	return s3sink.deleteObject(key)
+
+}
+
+func (s3sink *S3Sink) CreateEntry(key string, entry *filer_pb.Entry) error {
+
+	uploadId, err := s3sink.createMultipartUpload(key, entry)
+	if err != nil {
+		return err
+	}
+
+	totalSize := filer2.TotalSize(entry.Chunks)
+	chunkViews := filer2.ViewFromChunks(entry.Chunks, 0, int(totalSize))
+
+	var parts []*s3.CompletedPart
+	var wg sync.WaitGroup
+	for chunkIndex, chunk := range chunkViews {
+		partId := chunkIndex + 1
+		wg.Add(1)
+		go func(chunk *filer2.ChunkView) {
+			defer wg.Done()
+			if part, uploadErr := s3sink.uploadPart(key, uploadId, partId, chunk); uploadErr != nil {
+				err = uploadErr
+			} else {
+				parts = append(parts, part)
+			}
+		}(chunk)
+	}
+	wg.Wait()
+
+	if err != nil {
+		s3sink.abortMultipartUpload(key, uploadId)
+		return err
+	}
+
+	return s3sink.completeMultipartUpload(key, uploadId, parts)
+
+}
+
+func (s3sink *S3Sink) UpdateEntry(key string, oldEntry, newEntry *filer_pb.Entry, deleteIncludeChunks bool) (foundExistingEntry bool, err error) {
+	// TODO improve efficiency
+	return false, nil
+}
diff --git a/weed/replication/sink/s3sink/s3_write.go b/weed/replication/sink/s3sink/s3_write.go
new file mode 100644
index 000000000..df73e34a7
--- /dev/null
+++ b/weed/replication/sink/s3sink/s3_write.go
@@ -0,0 +1,165 @@
+package S3Sink
+
+import (
+	"github.com/aws/aws-sdk-go/service/s3"
+	"github.com/aws/aws-sdk-go/aws"
+	"github.com/chrislusf/seaweedfs/weed/glog"
+	"github.com/aws/aws-sdk-go/aws/awserr"
+	"fmt"
+	"io"
+	"github.com/chrislusf/seaweedfs/weed/pb/filer_pb"
+	"github.com/chrislusf/seaweedfs/weed/filer2"
+	"github.com/chrislusf/seaweedfs/weed/util"
+	"bytes"
+)
+
+func (s3sink *S3Sink) deleteObject(key string) error {
+	input := &s3.DeleteObjectInput{
+		Bucket: aws.String(s3sink.bucket),
+		Key:    aws.String(key),
+	}
+
+	result, err := s3sink.conn.DeleteObject(input)
+
+	if err == nil {
+		glog.V(0).Infof("[%s] delete %s: %v", s3sink.bucket, key, result)
+	} else {
+		glog.Errorf("[%s] delete %s: %v", s3sink.bucket, key, err)
+	}
+
+	return err
+
+}
+
+func (s3sink *S3Sink) createMultipartUpload(key string, entry *filer_pb.Entry) (uploadId string, err error) {
+	input := &s3.CreateMultipartUploadInput{
+		Bucket:      aws.String(s3sink.bucket),
+		Key:         aws.String(key),
+		ContentType: aws.String(entry.Attributes.Mime),
+	}
+
+	result, err := s3sink.conn.CreateMultipartUpload(input)
+
+	if err == nil {
+		glog.V(0).Infof("[%s] createMultipartUpload %s: %v", s3sink.bucket, key, result)
+	} else {
+		glog.Errorf("[%s] createMultipartUpload %s: %v", s3sink.bucket, key, err)
+		return "", err
+	}
+
+	return *result.UploadId, err
+}
+
+func (s3sink *S3Sink) abortMultipartUpload(key, uploadId string) error {
+	input := &s3.AbortMultipartUploadInput{
+		Bucket:   aws.String(s3sink.bucket),
+		Key:      aws.String(key),
+		UploadId: aws.String(uploadId),
+	}
+
+	result, err := s3sink.conn.AbortMultipartUpload(input)
+	if err != nil {
+		if aerr, ok := err.(awserr.Error); ok {
+			switch aerr.Code() {
+			case s3.ErrCodeNoSuchUpload:
+				glog.Errorf("[%s] abortMultipartUpload %s: %v %v", s3sink.bucket, key, s3.ErrCodeNoSuchUpload, aerr.Error())
+			default:
+				glog.Errorf("[%s] abortMultipartUpload %s: %v", s3sink.bucket, key, aerr.Error())
+			}
+		} else {
+			// Print the error, cast err to awserr.Error to get the Code and
+			// Message from an error.
+			glog.Errorf("[%s] abortMultipartUpload %s: %v", s3sink.bucket, key, aerr.Error())
+		}
+		return err
+	}
+
+	glog.V(0).Infof("[%s] abortMultipartUpload %s: %v", s3sink.bucket, key, result)
+
+	return nil
+}
+
+// To complete multipart upload
+func (s3sink *S3Sink) completeMultipartUpload(key, uploadId string, parts []*s3.CompletedPart) error {
+	input := &s3.CompleteMultipartUploadInput{
+		Bucket:   aws.String(s3sink.bucket),
+		Key:      aws.String(key),
+		UploadId: aws.String(uploadId),
+		MultipartUpload: &s3.CompletedMultipartUpload{
+			Parts: parts,
+		},
+	}
+
+	result, err := s3sink.conn.CompleteMultipartUpload(input)
+	if err == nil {
+		glog.V(0).Infof("[%s] completeMultipartUpload %s: %v", s3sink.bucket, key, result)
+	} else {
+		glog.Errorf("[%s] completeMultipartUpload %s: %v", s3sink.bucket, key, err)
+	}
+
+	return err
+}
+
+// To upload a part
+func (s3sink *S3Sink) uploadPart(key, uploadId string, partId int, chunk *filer2.ChunkView) (*s3.CompletedPart, error) {
+	var readSeeker io.ReadSeeker
+
+	readSeeker, err := s3sink.buildReadSeeker(chunk)
+	if err != nil {
+		glog.Errorf("[%s] uploadPart %s %d read: %v", s3sink.bucket, key, partId, err)
+		return nil, fmt.Errorf("[%s] uploadPart %s %d read: %v", s3sink.bucket, key, partId, err)
+	}
+
+	input := &s3.UploadPartInput{
+		Body:       readSeeker,
+		Bucket:     aws.String(s3sink.bucket),
+		Key:        aws.String(key),
+		PartNumber: aws.Int64(int64(partId)),
+		UploadId:   aws.String(uploadId),
+	}
+
+	result, err := s3sink.conn.UploadPart(input)
+	if err == nil {
+		glog.V(0).Infof("[%s] uploadPart %s %d upload: %v", s3sink.bucket, key, partId, result)
+	} else {
+		glog.Errorf("[%s] uploadPart %s %d upload: %v", s3sink.bucket, key, partId, err)
+	}
+
+	part := &s3.CompletedPart{
+		ETag:       result.ETag,
+		PartNumber: aws.Int64(int64(partId)),
+	}
+
+	return part, err
+}
+
+// To upload a part by copying byte range from an existing object as data source
+func (s3sink *S3Sink) uploadPartCopy(key, uploadId string, partId int64, copySource string, sourceStart, sourceStop int) error {
+	input := &s3.UploadPartCopyInput{
+		Bucket:          aws.String(s3sink.bucket),
+		CopySource:      aws.String(fmt.Sprintf("/%s/%s", s3sink.bucket, copySource)),
+		CopySourceRange: aws.String(fmt.Sprintf("bytes=%d-%d", sourceStart, sourceStop)),
+		Key:             aws.String(key),
+		PartNumber:      aws.Int64(partId),
+		UploadId:        aws.String(uploadId),
+	}
+
+	result, err := s3sink.conn.UploadPartCopy(input)
+	if err == nil {
+		glog.V(0).Infof("[%s] uploadPartCopy %s %d: %v", s3sink.bucket, key, partId, result)
+	} else {
+		glog.Errorf("[%s] uploadPartCopy %s %d: %v", s3sink.bucket, key, partId, err)
+	}
+
+	return err
+}
+
+func (s3sink *S3Sink) buildReadSeeker(chunk *filer2.ChunkView) (io.ReadSeeker, error) {
+	fileUrl, err := s3sink.filerSource.LookupFileId(chunk.FileId)
+	if err != nil {
+		return nil, err
+	}
+	buf := make([]byte, chunk.Size)
+	util.ReadUrl(fileUrl, chunk.Offset, int(chunk.Size), buf)
+	return bytes.NewReader(buf), nil
+}
diff --git a/weed/replication/source/filer_source.go b/weed/replication/source/filer_source.go
index 69e74a63c..efe71e706 100644
--- a/weed/replication/source/filer_source.go
+++ b/weed/replication/source/filer_source.go
@@ -34,7 +34,7 @@ func (fs *FilerSource) initialize(grpcAddress string, dir string) (err error) {
 	return nil
 }
 
-func (fs *FilerSource) ReadPart(part string) (filename string, header http.Header, readCloser io.ReadCloser, err error) {
+func (fs *FilerSource) LookupFileId(part string) (fileUrl string, err error) {
 
 	vid2Locations := make(map[string]*filer_pb.Locations)
 
@@ -56,18 +56,28 @@ func (fs *FilerSource) ReadPart(part string) (filename string, header http.Heade
 	})
 
 	if err != nil {
-		glog.V(1).Infof("replication lookup volume id %s: %v", vid, err)
-		return "", nil, nil, fmt.Errorf("replication lookup volume id %s: %v", vid, err)
+		glog.V(1).Infof("LookupFileId volume id %s: %v", vid, err)
+		return "", fmt.Errorf("LookupFileId volume id %s: %v", vid, err)
 	}
 
 	locations := vid2Locations[vid]
 
 	if locations == nil || len(locations.Locations) == 0 {
-		glog.V(1).Infof("replication locate volume id %s: %v", vid, err)
-		return "", nil, nil, fmt.Errorf("replication locate volume id %s: %v", vid, err)
+		glog.V(1).Infof("LookupFileId locate volume id %s: %v", vid, err)
+		return "", fmt.Errorf("LookupFileId locate volume id %s: %v", vid, err)
 	}
 
-	fileUrl := fmt.Sprintf("http://%s/%s", locations.Locations[0].Url, part)
+	fileUrl = fmt.Sprintf("http://%s/%s", locations.Locations[0].Url, part)
+
+	return
+}
+
+func (fs *FilerSource) ReadPart(part string) (filename string, header http.Header, readCloser io.ReadCloser, err error) {
+
+	fileUrl, err := fs.LookupFileId(part)
+	if err != nil {
+		return "", nil, nil, err
+	}
 
 	filename, header, readCloser, err = util.DownloadFile(fileUrl)