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- package aufs
- import (
- "encoding/json"
- "fmt"
- "io/ioutil"
- "os"
- "path"
- )
- type metadata struct {
- ID string `json:"id"`
- ParentID string `json:"parent,omitempty"`
- Image string `json:"Image,omitempty"`
- parent *metadata
- }
- func pathExists(pth string) bool {
- if _, err := os.Stat(pth); err != nil {
- return false
- }
- return true
- }
- // Migrate existing images and containers from docker < 0.7.x
- //
- // The format pre 0.7 is for docker to store the metadata and filesystem
- // content in the same directory. For the migration to work we need to move Image layer
- // data from /var/lib/docker/graph/<id>/layers to the diff of the registered id.
- //
- // Next we need to migrate the container's rw layer to diff of the driver. After the
- // contents are migrated we need to register the image and container ids with the
- // driver.
- //
- // For the migration we try to move the folder containing the layer files, if that
- // fails because the data is currently mounted we will fallback to creating a
- // symlink.
- func (a *Driver) Migrate(pth string, setupInit func(p string) error) error {
- if pathExists(path.Join(pth, "graph")) {
- if err := a.migrateRepositories(pth); err != nil {
- return err
- }
- if err := a.migrateImages(path.Join(pth, "graph")); err != nil {
- return err
- }
- return a.migrateContainers(path.Join(pth, "containers"), setupInit)
- }
- return nil
- }
- func (a *Driver) migrateRepositories(pth string) error {
- name := path.Join(pth, "repositories")
- if err := os.Rename(name, name+"-aufs"); err != nil && !os.IsNotExist(err) {
- return err
- }
- return nil
- }
- func (a *Driver) migrateContainers(pth string, setupInit func(p string) error) error {
- fis, err := ioutil.ReadDir(pth)
- if err != nil {
- return err
- }
- for _, fi := range fis {
- if id := fi.Name(); fi.IsDir() && pathExists(path.Join(pth, id, "rw")) {
- if err := tryRelocate(path.Join(pth, id, "rw"), path.Join(a.rootPath(), "diff", id)); err != nil {
- return err
- }
- if !a.Exists(id) {
- metadata, err := loadMetadata(path.Join(pth, id, "config.json"))
- if err != nil {
- return err
- }
- initID := fmt.Sprintf("%s-init", id)
- if err := a.Create(initID, metadata.Image); err != nil {
- return err
- }
- initPath, err := a.Get(initID, "")
- if err != nil {
- return err
- }
- // setup init layer
- if err := setupInit(initPath); err != nil {
- return err
- }
- if err := a.Create(id, initID); err != nil {
- return err
- }
- }
- }
- }
- return nil
- }
- func (a *Driver) migrateImages(pth string) error {
- fis, err := ioutil.ReadDir(pth)
- if err != nil {
- return err
- }
- var (
- m = make(map[string]*metadata)
- current *metadata
- exists bool
- )
- for _, fi := range fis {
- if id := fi.Name(); fi.IsDir() && pathExists(path.Join(pth, id, "layer")) {
- if current, exists = m[id]; !exists {
- current, err = loadMetadata(path.Join(pth, id, "json"))
- if err != nil {
- return err
- }
- m[id] = current
- }
- }
- }
- for _, v := range m {
- v.parent = m[v.ParentID]
- }
- migrated := make(map[string]bool)
- for _, v := range m {
- if err := a.migrateImage(v, pth, migrated); err != nil {
- return err
- }
- }
- return nil
- }
- func (a *Driver) migrateImage(m *metadata, pth string, migrated map[string]bool) error {
- if !migrated[m.ID] {
- if m.parent != nil {
- a.migrateImage(m.parent, pth, migrated)
- }
- if err := tryRelocate(path.Join(pth, m.ID, "layer"), path.Join(a.rootPath(), "diff", m.ID)); err != nil {
- return err
- }
- if !a.Exists(m.ID) {
- if err := a.Create(m.ID, m.ParentID); err != nil {
- return err
- }
- }
- migrated[m.ID] = true
- }
- return nil
- }
- // tryRelocate will try to rename the old path to the new pack and if
- // the operation fails, it will fallback to a symlink
- func tryRelocate(oldPath, newPath string) error {
- s, err := os.Lstat(newPath)
- if err != nil && !os.IsNotExist(err) {
- return err
- }
- // If the destination is a symlink then we already tried to relocate once before
- // and it failed so we delete it and try to remove
- if s != nil && s.Mode()&os.ModeSymlink == os.ModeSymlink {
- if err := os.RemoveAll(newPath); err != nil {
- return err
- }
- }
- if err := os.Rename(oldPath, newPath); err != nil {
- if sErr := os.Symlink(oldPath, newPath); sErr != nil {
- return fmt.Errorf("Unable to relocate %s to %s: Rename err %s Symlink err %s", oldPath, newPath, err, sErr)
- }
- }
- return nil
- }
- func loadMetadata(pth string) (*metadata, error) {
- f, err := os.Open(pth)
- if err != nil {
- return nil, err
- }
- defer f.Close()
- var (
- out = &metadata{}
- dec = json.NewDecoder(f)
- )
- if err := dec.Decode(out); err != nil {
- return nil, err
- }
- return out, nil
- }
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