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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
}
|
