package image import ( "encoding/json" "errors" "fmt" "sync" "github.com/Sirupsen/logrus" "github.com/docker/distribution/digest" "github.com/docker/docker/layer" ) // Store is an interface for creating and accessing images type Store interface { Create(config []byte) (ID, error) Get(id ID) (*Image, error) Delete(id ID) ([]layer.Metadata, error) Search(partialID string) (ID, error) SetParent(id ID, parent ID) error GetParent(id ID) (ID, error) Children(id ID) []ID Map() map[ID]*Image Heads() map[ID]*Image } // LayerGetReleaser is a minimal interface for getting and releasing images. type LayerGetReleaser interface { Get(layer.ChainID) (layer.Layer, error) Release(layer.Layer) ([]layer.Metadata, error) } type imageMeta struct { layer layer.Layer children map[ID]struct{} } type store struct { sync.Mutex ls LayerGetReleaser images map[ID]*imageMeta fs StoreBackend digestSet *digest.Set } // NewImageStore returns new store object for given layer store func NewImageStore(fs StoreBackend, ls LayerGetReleaser) (Store, error) { is := &store{ ls: ls, images: make(map[ID]*imageMeta), fs: fs, digestSet: digest.NewSet(), } // load all current images and retain layers if err := is.restore(); err != nil { return nil, err } return is, nil } func (is *store) restore() error { err := is.fs.Walk(func(id ID) error { img, err := is.Get(id) if err != nil { logrus.Errorf("invalid image %v, %v", id, err) return nil } var l layer.Layer if chainID := img.RootFS.ChainID(); chainID != "" { l, err = is.ls.Get(chainID) if err != nil { return err } } if err := is.digestSet.Add(digest.Digest(id)); err != nil { return err } imageMeta := &imageMeta{ layer: l, children: make(map[ID]struct{}), } is.images[ID(id)] = imageMeta return nil }) if err != nil { return err } // Second pass to fill in children maps for id := range is.images { if parent, err := is.GetParent(id); err == nil { if parentMeta := is.images[parent]; parentMeta != nil { parentMeta.children[id] = struct{}{} } } } return nil } func (is *store) Create(config []byte) (ID, error) { var img Image err := json.Unmarshal(config, &img) if err != nil { return "", err } // Must reject any config that references diffIDs from the history // which aren't among the rootfs layers. rootFSLayers := make(map[layer.DiffID]struct{}) for _, diffID := range img.RootFS.DiffIDs { rootFSLayers[diffID] = struct{}{} } layerCounter := 0 for _, h := range img.History { if !h.EmptyLayer { layerCounter++ } } if layerCounter > len(img.RootFS.DiffIDs) { return "", errors.New("too many non-empty layers in History section") } dgst, err := is.fs.Set(config) if err != nil { return "", err } imageID := ID(dgst) is.Lock() defer is.Unlock() if _, exists := is.images[imageID]; exists { return imageID, nil } layerID := img.RootFS.ChainID() var l layer.Layer if layerID != "" { l, err = is.ls.Get(layerID) if err != nil { return "", err } } imageMeta := &imageMeta{ layer: l, children: make(map[ID]struct{}), } is.images[imageID] = imageMeta if err := is.digestSet.Add(digest.Digest(imageID)); err != nil { delete(is.images, imageID) return "", err } return imageID, nil } func (is *store) Search(term string) (ID, error) { is.Lock() defer is.Unlock() dgst, err := is.digestSet.Lookup(term) if err != nil { return "", err } return ID(dgst), nil } func (is *store) Get(id ID) (*Image, error) { // todo: Check if image is in images // todo: Detect manual insertions and start using them config, err := is.fs.Get(id) if err != nil { return nil, err } img, err := NewFromJSON(config) if err != nil { return nil, err } img.computedID = id img.Parent, err = is.GetParent(id) if err != nil { img.Parent = "" } return img, nil } func (is *store) Delete(id ID) ([]layer.Metadata, error) { is.Lock() defer is.Unlock() imageMeta := is.images[id] if imageMeta == nil { return nil, fmt.Errorf("unrecognized image ID %s", id.String()) } for id := range imageMeta.children { is.fs.DeleteMetadata(id, "parent") } if parent, err := is.GetParent(id); err == nil && is.images[parent] != nil { delete(is.images[parent].children, id) } delete(is.images, id) is.fs.Delete(id) if imageMeta.layer != nil { return is.ls.Release(imageMeta.layer) } return nil, nil } func (is *store) SetParent(id, parent ID) error { is.Lock() defer is.Unlock() parentMeta := is.images[parent] if parentMeta == nil { return fmt.Errorf("unknown parent image ID %s", parent.String()) } parentMeta.children[id] = struct{}{} return is.fs.SetMetadata(id, "parent", []byte(parent)) } func (is *store) GetParent(id ID) (ID, error) { d, err := is.fs.GetMetadata(id, "parent") if err != nil { return "", err } return ID(d), nil // todo: validate? } func (is *store) Children(id ID) []ID { is.Lock() defer is.Unlock() return is.children(id) } func (is *store) children(id ID) []ID { var ids []ID if is.images[id] != nil { for id := range is.images[id].children { ids = append(ids, id) } } return ids } func (is *store) Heads() map[ID]*Image { return is.imagesMap(false) } func (is *store) Map() map[ID]*Image { return is.imagesMap(true) } func (is *store) imagesMap(all bool) map[ID]*Image { is.Lock() defer is.Unlock() images := make(map[ID]*Image) for id := range is.images { if !all && len(is.children(id)) > 0 { continue } img, err := is.Get(id) if err != nil { logrus.Errorf("invalid image access: %q, error: %q", id, err) continue } images[id] = img } return images }