// MetastoreBackup returns a snapshot of the meta store.
func (c *Client) MetastoreBackup() (*meta.Data, error) {
req := &Request{
Type: RequestMetastoreBackup,
}
b, err := c.doRequest(req)
if err != nil {
return nil, err
}
// Check the magic.
magic := binary.BigEndian.Uint64(b[:8])
if magic != BackupMagicHeader {
return nil, errors.New("invalid metadata received")
}
i := 8
// Size of the meta store bytes.
length := int(binary.BigEndian.Uint64(b[i : i+8]))
i += 8
metaBytes := b[i : i+length]
i += int(length)
// Unpack meta data.
var data meta.Data
if err := data.UnmarshalBinary(metaBytes); err != nil {
return nil, fmt.Errorf("unmarshal: %s", err)
}
return &data, nil
}
// unpackMeta reads the metadata from the backup directory and initializes a raft
// cluster and replaces the root metadata.
func (cmd *Command) unpackMeta() error {
// find the meta file
metaFiles, err := filepath.Glob(filepath.Join(cmd.backupFilesPath, backup.Metafile+".*"))
if err != nil {
return err
}
if len(metaFiles) == 0 {
return fmt.Errorf("no metastore backups in %s", cmd.backupFilesPath)
}
latest := metaFiles[len(metaFiles)-1]
fmt.Fprintf(cmd.Stdout, "Using metastore snapshot: %v\n", latest)
// Read the metastore backup
f, err := os.Open(latest)
if err != nil {
return err
}
var buf bytes.Buffer
if _, err := io.Copy(&buf, f); err != nil {
return fmt.Errorf("copy: %s", err)
}
b := buf.Bytes()
var i int
// Make sure the file is actually a meta store backup file
magic := binary.BigEndian.Uint64(b[:8])
if magic != snapshotter.BackupMagicHeader {
return fmt.Errorf("invalid metadata file")
}
i += 8
// Size of the meta store bytes
length := int(binary.BigEndian.Uint64(b[i : i+8]))
i += 8
metaBytes := b[i : i+length]
i += int(length)
// Size of the node.json bytes
length = int(binary.BigEndian.Uint64(b[i : i+8]))
i += 8
nodeBytes := b[i:]
// Unpack into metadata.
var data meta.Data
if err := data.UnmarshalBinary(metaBytes); err != nil {
return fmt.Errorf("unmarshal: %s", err)
}
// Copy meta config and remove peers so it starts in single mode.
c := cmd.MetaConfig
c.Dir = cmd.metadir
// Create the meta dir
if os.MkdirAll(c.Dir, 0700); err != nil {
return err
}
// Write node.json back to meta dir
if err := ioutil.WriteFile(filepath.Join(c.Dir, "node.json"), nodeBytes, 0655); err != nil {
return err
}
client := meta.NewClient(c)
client.SetLogger(log.New(ioutil.Discard, "", 0))
if err := client.Open(); err != nil {
return err
}
defer client.Close()
// Force set the full metadata.
if err := client.SetData(&data); err != nil {
return fmt.Errorf("set data: %s", err)
}
// remove the raft.db file if it exists
err = os.Remove(filepath.Join(cmd.metadir, "raft.db"))
if err != nil {
if os.IsNotExist(err) {
return nil
}
return err
}
// remove the node.json file if it exists
err = os.Remove(filepath.Join(cmd.metadir, "node.json"))
if err != nil {
if os.IsNotExist(err) {
return nil
}
return err
}
return nil
}