diff options
Diffstat (limited to 'runtime/graphdriver/aufs/migrate.go')
| -rw-r--r-- | runtime/graphdriver/aufs/migrate.go | 194 |
1 files changed, 194 insertions, 0 deletions
diff --git a/runtime/graphdriver/aufs/migrate.go b/runtime/graphdriver/aufs/migrate.go new file mode 100644 index 0000000000..400e260797 --- /dev/null +++ b/runtime/graphdriver/aufs/migrate.go @@ -0,0 +1,194 @@ +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 +} |