1 files changed, 227 insertions, 0 deletions
diff --git a/weed/shell/command_remote_mount.go b/weed/shell/command_remote_mount.go
new file mode 100644
index 000000000..8f16d27c8
--- /dev/null
+++ b/weed/shell/command_remote_mount.go
@@ -0,0 +1,227 @@
+package shell
+
+import (
+	"context"
+	"flag"
+	"fmt"
+	"github.com/chrislusf/seaweedfs/weed/filer"
+	"github.com/chrislusf/seaweedfs/weed/pb/filer_pb"
+	"github.com/chrislusf/seaweedfs/weed/remote_storage"
+	"github.com/chrislusf/seaweedfs/weed/util"
+	"github.com/golang/protobuf/proto"
+	"io"
+)
+
+func init() {
+	Commands = append(Commands, &commandRemoteMount{})
+}
+
+type commandRemoteMount struct {
+}
+
+func (c *commandRemoteMount) Name() string {
+	return "remote.mount"
+}
+
+func (c *commandRemoteMount) Help() string {
+	return `mount remote storage and pull its metadata
+
+	# assume a remote storage is configured to name "s3_1"
+	remote.configure -name=s3_1 -type=s3 -access_key=xxx -secret_key=yyy
+
+	# mount and pull one bucket
+	remote.mount -dir=xxx -remote=s3_1/bucket
+	# mount and pull one directory in the bucket
+	remote.mount -dir=xxx -remote=s3_1/bucket/dir1
+
+`
+}
+
+func (c *commandRemoteMount) Do(args []string, commandEnv *CommandEnv, writer io.Writer) (err error) {
+
+	remoteMountCommand := flag.NewFlagSet(c.Name(), flag.ContinueOnError)
+
+	dir := remoteMountCommand.String("dir", "", "a directory in filer")
+	nonEmpty := remoteMountCommand.Bool("nonempty", false, "allows the mounting over a non-empty directory")
+	remote := remoteMountCommand.String("remote", "", "a directory in remote storage, ex. <storageName>/<bucket>/path/to/dir")
+
+	if err = remoteMountCommand.Parse(args); err != nil {
+		return nil
+	}
+
+	remoteStorageLocation := remote_storage.ParseLocation(*remote)
+
+	// find configuration for remote storage
+	// remotePath is /<bucket>/path/to/dir
+	remoteConf, err := c.findRemoteStorageConfiguration(commandEnv, writer, remoteStorageLocation)
+	if err != nil {
+		return fmt.Errorf("find configuration for %s: %v", *remote, err)
+	}
+
+	// pull metadata from remote
+	if err = c.pullMetadata(commandEnv, writer, *dir, *nonEmpty, remoteConf, remoteStorageLocation); err != nil {
+		return fmt.Errorf("pull metadata: %v", err)
+	}
+
+	// store a mount configuration in filer
+	if err = c.saveMountMapping(commandEnv, writer, *dir, remoteStorageLocation); err != nil {
+		return fmt.Errorf("save mount mapping: %v", err)
+	}
+
+	return nil
+}
+
+func (c *commandRemoteMount) findRemoteStorageConfiguration(commandEnv *CommandEnv, writer io.Writer, remote *filer_pb.RemoteStorageLocation) (conf *filer_pb.RemoteConf, err error) {
+
+	// read storage configuration data
+	var confBytes []byte
+	err = commandEnv.WithFilerClient(func(client filer_pb.SeaweedFilerClient) error {
+		confBytes, err = filer.ReadInsideFiler(client, filer.DirectoryEtcRemote, remote.Name+filer.REMOTE_STORAGE_CONF_SUFFIX)
+		return err
+	})
+	if err != nil {
+		err = fmt.Errorf("no remote storage configuration for %s : %v", remote.Name, err)
+		return
+	}
+
+	// unmarshal storage configuration
+	conf = &filer_pb.RemoteConf{}
+	if unMarshalErr := proto.Unmarshal(confBytes, conf); unMarshalErr != nil {
+		err = fmt.Errorf("unmarshal %s/%s: %v", filer.DirectoryEtcRemote, remote.Name, unMarshalErr)
+		return
+	}
+
+	return
+}
+
+func (c *commandRemoteMount) pullMetadata(commandEnv *CommandEnv, writer io.Writer, dir string, nonEmpty bool, remoteConf *filer_pb.RemoteConf, remote *filer_pb.RemoteStorageLocation) error {
+
+	// find existing directory, and ensure the directory is empty
+	var mountToDir *filer_pb.Entry
+	err := commandEnv.WithFilerClient(func(client filer_pb.SeaweedFilerClient) error {
+		parent, name := util.FullPath(dir).DirAndName()
+		resp, lookupErr := client.LookupDirectoryEntry(context.Background(), &filer_pb.LookupDirectoryEntryRequest{
+			Directory: parent,
+			Name:      name,
+		})
+		if lookupErr != nil {
+			return fmt.Errorf("lookup %s: %v", dir, lookupErr)
+		}
+		mountToDir = resp.Entry
+
+		mountToDirIsEmpty := true
+		listErr := filer_pb.SeaweedList(client, dir, "", func(entry *filer_pb.Entry, isLast bool) error {
+			mountToDirIsEmpty = false
+			return nil
+		}, "", false, 1)
+
+		if listErr != nil {
+			return fmt.Errorf("list %s: %v", dir, listErr)
+		}
+
+		if !mountToDirIsEmpty {
+			if !nonEmpty {
+				return fmt.Errorf("dir %s is not empty", dir)
+			}
+		}
+
+		return nil
+	})
+	if err != nil {
+		return err
+	}
+
+	// visit remote storage
+	remoteStorage, err := remote_storage.GetRemoteStorage(remoteConf)
+	if err != nil {
+		return err
+	}
+
+	err = commandEnv.WithFilerClient(func(client filer_pb.SeaweedFilerClient) error {
+		ctx := context.Background()
+		err = remoteStorage.Traverse(remote, func(remoteDir, name string, isDirectory bool, remoteEntry *filer_pb.RemoteEntry) error {
+			localDir := dir + remoteDir
+			println(util.NewFullPath(localDir, name))
+
+			lookupResponse, lookupErr := filer_pb.LookupEntry(client, &filer_pb.LookupDirectoryEntryRequest{
+				Directory: localDir,
+				Name:      name,
+			})
+			var existingEntry *filer_pb.Entry
+			if lookupErr != nil {
+				if lookupErr != filer_pb.ErrNotFound {
+					return lookupErr
+				}
+			} else {
+				existingEntry = lookupResponse.Entry
+			}
+
+			if existingEntry == nil {
+				_, createErr := client.CreateEntry(ctx, &filer_pb.CreateEntryRequest{
+					Directory: localDir,
+					Entry: &filer_pb.Entry{
+						Name:        name,
+						IsDirectory: isDirectory,
+						Attributes: &filer_pb.FuseAttributes{
+							FileSize: uint64(remoteEntry.Size),
+							Mtime:    remoteEntry.LastModifiedAt,
+							FileMode: uint32(0644),
+						},
+						RemoteEntry: remoteEntry,
+					},
+				})
+				return createErr
+			} else {
+				if existingEntry.RemoteEntry == nil || existingEntry.RemoteEntry.ETag != remoteEntry.ETag {
+					existingEntry.RemoteEntry = remoteEntry
+					existingEntry.Attributes.FileSize = uint64(remoteEntry.Size)
+					existingEntry.Attributes.Mtime = remoteEntry.LastModifiedAt
+					_, updateErr := client.UpdateEntry(ctx, &filer_pb.UpdateEntryRequest{
+						Directory: localDir,
+						Entry: existingEntry,
+					})
+					return updateErr
+				}
+			}
+			return nil
+		})
+		return err
+	})
+
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (c *commandRemoteMount) saveMountMapping(commandEnv *CommandEnv, writer io.Writer, dir string, remoteStorageLocation *filer_pb.RemoteStorageLocation) (err error) {
+
+	// read current mapping
+	var oldContent, newContent []byte
+	err = commandEnv.WithFilerClient(func(client filer_pb.SeaweedFilerClient) error {
+		oldContent, err = filer.ReadInsideFiler(client, filer.DirectoryEtcRemote, filer.REMOTE_STORAGE_MOUNT_FILE)
+		return err
+	})
+	if err != nil {
+		if err != filer_pb.ErrNotFound {
+			return fmt.Errorf("read existing mapping: %v", err)
+		}
+	}
+
+	// add new mapping
+	newContent, err = filer.AddMapping(oldContent, dir, remoteStorageLocation)
+	if err != nil {
+		return fmt.Errorf("add mapping %s~%s: %v", dir, remoteStorageLocation, err)
+	}
+
+	// save back
+	err = commandEnv.WithFilerClient(func(client filer_pb.SeaweedFilerClient) error {
+		return filer.SaveInsideFiler(client, filer.DirectoryEtcRemote, filer.REMOTE_STORAGE_MOUNT_FILE, newContent)
+	})
+	if err != nil {
+		return fmt.Errorf("save mapping: %v", err)
+	}
+
+	return nil
+}