package image import ( "encoding/json" "fmt" "io/ioutil" "os" "path" "strconv" "time" log "github.com/Sirupsen/logrus" "github.com/docker/docker/pkg/archive" "github.com/docker/docker/pkg/tarsum" "github.com/docker/docker/runconfig" "github.com/docker/docker/utils" ) // Set the max depth to the aufs default that most // kernels are compiled with // For more information see: http://sourceforge.net/p/aufs/aufs3-standalone/ci/aufs3.12/tree/config.mk const MaxImageDepth = 127 type Image struct { ID string `json:"id"` Parent string `json:"parent,omitempty"` Comment string `json:"comment,omitempty"` Created time.Time `json:"created"` Container string `json:"container,omitempty"` ContainerConfig runconfig.Config `json:"container_config,omitempty"` DockerVersion string `json:"docker_version,omitempty"` Author string `json:"author,omitempty"` Config *runconfig.Config `json:"config,omitempty"` Architecture string `json:"architecture,omitempty"` OS string `json:"os,omitempty"` Checksum string `json:"checksum"` Size int64 graph Graph } func LoadImage(root string) (*Image, error) { // Open the JSON file to decode by streaming jsonSource, err := os.Open(jsonPath(root)) if err != nil { return nil, err } defer jsonSource.Close() img := &Image{} dec := json.NewDecoder(jsonSource) // Decode the JSON data if err := dec.Decode(img); err != nil { return nil, err } if err := utils.ValidateID(img.ID); err != nil { return nil, err } if buf, err := ioutil.ReadFile(path.Join(root, "layersize")); err != nil { if !os.IsNotExist(err) { return nil, err } // If the layersize file does not exist then set the size to a negative number // because a layer size of 0 (zero) is valid img.Size = -1 } else { // Using Atoi here instead would temporarily convert the size to a machine // dependent integer type, which causes images larger than 2^31 bytes to // display negative sizes on 32-bit machines: size, err := strconv.ParseInt(string(buf), 10, 64) if err != nil { return nil, err } img.Size = int64(size) } return img, nil } // StoreImage stores file system layer data for the given image to the // image's registered storage driver. Image metadata is stored in a file // at the specified root directory. This function also computes the TarSum // of `layerData` (currently using tarsum.dev). func StoreImage(img *Image, layerData archive.ArchiveReader, root string) error { // Store the layer var ( size int64 err error driver = img.graph.Driver() layerTarSum tarsum.TarSum ) // If layerData is not nil, unpack it into the new layer if layerData != nil { layerDataDecompressed, err := archive.DecompressStream(layerData) if err != nil { return err } defer layerDataDecompressed.Close() if layerTarSum, err = tarsum.NewTarSum(layerDataDecompressed, true, tarsum.VersionDev); err != nil { return err } if size, err = driver.ApplyDiff(img.ID, img.Parent, layerTarSum); err != nil { return err } checksum := layerTarSum.Sum(nil) if img.Checksum != "" && img.Checksum != checksum { log.Warnf("image layer checksum mismatch: computed %q, expected %q", checksum, img.Checksum) } img.Checksum = checksum } img.Size = size if err := img.SaveSize(root); err != nil { return err } f, err := os.OpenFile(jsonPath(root), os.O_CREATE|os.O_WRONLY|os.O_TRUNC, os.FileMode(0600)) if err != nil { return err } defer f.Close() return json.NewEncoder(f).Encode(img) } func (img *Image) SetGraph(graph Graph) { img.graph = graph } // SaveSize stores the current `size` value of `img` in the directory `root`. func (img *Image) SaveSize(root string) error { if err := ioutil.WriteFile(path.Join(root, "layersize"), []byte(strconv.Itoa(int(img.Size))), 0600); err != nil { return fmt.Errorf("Error storing image size in %s/layersize: %s", root, err) } return nil } func jsonPath(root string) string { return path.Join(root, "json") } func (img *Image) RawJson() ([]byte, error) { root, err := img.root() if err != nil { return nil, fmt.Errorf("Failed to get root for image %s: %s", img.ID, err) } fh, err := os.Open(jsonPath(root)) if err != nil { return nil, fmt.Errorf("Failed to open json for image %s: %s", img.ID, err) } buf, err := ioutil.ReadAll(fh) if err != nil { return nil, fmt.Errorf("Failed to read json for image %s: %s", img.ID, err) } return buf, nil } // TarLayer returns a tar archive of the image's filesystem layer. func (img *Image) TarLayer() (arch archive.Archive, err error) { if img.graph == nil { return nil, fmt.Errorf("Can't load storage driver for unregistered image %s", img.ID) } driver := img.graph.Driver() return driver.Diff(img.ID, img.Parent) } // Image includes convenience proxy functions to its graph // These functions will return an error if the image is not registered // (ie. if image.graph == nil) func (img *Image) History() ([]*Image, error) { var parents []*Image if err := img.WalkHistory( func(img *Image) error { parents = append(parents, img) return nil }, ); err != nil { return nil, err } return parents, nil } func (img *Image) WalkHistory(handler func(*Image) error) (err error) { currentImg := img for currentImg != nil { if handler != nil { if err := handler(currentImg); err != nil { return err } } currentImg, err = currentImg.GetParent() if err != nil { return fmt.Errorf("Error while getting parent image: %v", err) } } return nil } func (img *Image) GetParent() (*Image, error) { if img.Parent == "" { return nil, nil } if img.graph == nil { return nil, fmt.Errorf("Can't lookup parent of unregistered image") } return img.graph.Get(img.Parent) } func (img *Image) root() (string, error) { if img.graph == nil { return "", fmt.Errorf("Can't lookup root of unregistered image") } return img.graph.ImageRoot(img.ID), nil } func (img *Image) GetParentsSize(size int64) int64 { parentImage, err := img.GetParent() if err != nil || parentImage == nil { return size } size += parentImage.Size return parentImage.GetParentsSize(size) } // Depth returns the number of parents for a // current image func (img *Image) Depth() (int, error) { var ( count = 0 parent = img err error ) for parent != nil { count++ parent, err = parent.GetParent() if err != nil { return -1, err } } return count, nil } // CheckDepth returns an error if the depth of an image, as returned // by ImageDepth, is too large to support creating a container from it // on this daemon. func (img *Image) CheckDepth() error { // We add 2 layers to the depth because the container's rw and // init layer add to the restriction depth, err := img.Depth() if err != nil { return err } if depth+2 >= MaxImageDepth { return fmt.Errorf("Cannot create container with more than %d parents", MaxImageDepth) } return nil } // Build an Image object from raw json data func NewImgJSON(src []byte) (*Image, error) { ret := &Image{} log.Debugf("Json string: {%s}", src) // FIXME: Is there a cleaner way to "purify" the input json? if err := json.Unmarshal(src, ret); err != nil { return nil, err } return ret, nil }