| package graph |
| |
| import ( |
| "compress/gzip" |
| "crypto/sha256" |
| "encoding/json" |
| "errors" |
| "fmt" |
| "io" |
| "io/ioutil" |
| "os" |
| "path/filepath" |
| "runtime" |
| "strconv" |
| "strings" |
| "sync" |
| "time" |
| |
| "github.com/Sirupsen/logrus" |
| "github.com/docker/distribution/digest" |
| "github.com/docker/docker/autogen/dockerversion" |
| "github.com/docker/docker/daemon/graphdriver" |
| "github.com/docker/docker/image" |
| "github.com/docker/docker/pkg/archive" |
| "github.com/docker/docker/pkg/progressreader" |
| "github.com/docker/docker/pkg/streamformatter" |
| "github.com/docker/docker/pkg/stringid" |
| "github.com/docker/docker/pkg/system" |
| "github.com/docker/docker/pkg/truncindex" |
| "github.com/docker/docker/runconfig" |
| "github.com/vbatts/tar-split/tar/asm" |
| "github.com/vbatts/tar-split/tar/storage" |
| ) |
| |
| // The type is used to protect pulling or building related image |
| // layers from deleteing when filtered by dangling=true |
| // The key of layers is the images ID which is pulling or building |
| // The value of layers is a slice which hold layer IDs referenced to |
| // pulling or building images |
| type retainedLayers struct { |
| layerHolders map[string]map[string]struct{} // map[layerID]map[sessionID] |
| sync.Mutex |
| } |
| |
| func (r *retainedLayers) Add(sessionID string, layerIDs []string) { |
| r.Lock() |
| defer r.Unlock() |
| for _, layerID := range layerIDs { |
| if r.layerHolders[layerID] == nil { |
| r.layerHolders[layerID] = map[string]struct{}{} |
| } |
| r.layerHolders[layerID][sessionID] = struct{}{} |
| } |
| } |
| |
| func (r *retainedLayers) Delete(sessionID string, layerIDs []string) { |
| r.Lock() |
| defer r.Unlock() |
| for _, layerID := range layerIDs { |
| holders, ok := r.layerHolders[layerID] |
| if !ok { |
| continue |
| } |
| delete(holders, sessionID) |
| if len(holders) == 0 { |
| delete(r.layerHolders, layerID) // Delete any empty reference set. |
| } |
| } |
| } |
| |
| func (r *retainedLayers) Exists(layerID string) bool { |
| r.Lock() |
| _, exists := r.layerHolders[layerID] |
| r.Unlock() |
| return exists |
| } |
| |
| // A Graph is a store for versioned filesystem images and the relationship between them. |
| type Graph struct { |
| root string |
| idIndex *truncindex.TruncIndex |
| driver graphdriver.Driver |
| imageMutex imageMutex // protect images in driver. |
| retained *retainedLayers |
| } |
| |
| // file names for ./graph/<ID>/ |
| const ( |
| jsonFileName = "json" |
| layersizeFileName = "layersize" |
| digestFileName = "checksum" |
| tarDataFileName = "tar-data.json.gz" |
| ) |
| |
| var ( |
| // ErrDigestNotSet is used when request the digest for a layer |
| // but the layer has no digest value or content to compute the |
| // the digest. |
| ErrDigestNotSet = errors.New("digest is not set for layer") |
| ) |
| |
| // NewGraph instantiates a new graph at the given root path in the filesystem. |
| // `root` will be created if it doesn't exist. |
| func NewGraph(root string, driver graphdriver.Driver) (*Graph, error) { |
| abspath, err := filepath.Abs(root) |
| if err != nil { |
| return nil, err |
| } |
| // Create the root directory if it doesn't exists |
| if err := system.MkdirAll(root, 0700); err != nil && !os.IsExist(err) { |
| return nil, err |
| } |
| |
| graph := &Graph{ |
| root: abspath, |
| idIndex: truncindex.NewTruncIndex([]string{}), |
| driver: driver, |
| retained: &retainedLayers{layerHolders: make(map[string]map[string]struct{})}, |
| } |
| if err := graph.restore(); err != nil { |
| return nil, err |
| } |
| return graph, nil |
| } |
| |
| // IsHeld returns whether the given layerID is being used by an ongoing pull or build. |
| func (graph *Graph) IsHeld(layerID string) bool { |
| return graph.retained.Exists(layerID) |
| } |
| |
| func (graph *Graph) restore() error { |
| dir, err := ioutil.ReadDir(graph.root) |
| if err != nil { |
| return err |
| } |
| var ids = []string{} |
| for _, v := range dir { |
| id := v.Name() |
| if graph.driver.Exists(id) { |
| ids = append(ids, id) |
| } |
| } |
| |
| baseIds, err := graph.restoreBaseImages() |
| if err != nil { |
| return err |
| } |
| ids = append(ids, baseIds...) |
| |
| graph.idIndex = truncindex.NewTruncIndex(ids) |
| logrus.Debugf("Restored %d elements", len(ids)) |
| return nil |
| } |
| |
| // FIXME: Implement error subclass instead of looking at the error text |
| // Note: This is the way golang implements os.IsNotExists on Plan9 |
| func (graph *Graph) IsNotExist(err error, id string) bool { |
| return err != nil && (strings.Contains(strings.ToLower(err.Error()), "does not exist") || strings.Contains(strings.ToLower(err.Error()), "no such")) && strings.Contains(err.Error(), id) |
| } |
| |
| // Exists returns true if an image is registered at the given id. |
| // If the image doesn't exist or if an error is encountered, false is returned. |
| func (graph *Graph) Exists(id string) bool { |
| if _, err := graph.Get(id); err != nil { |
| return false |
| } |
| return true |
| } |
| |
| // Get returns the image with the given id, or an error if the image doesn't exist. |
| func (graph *Graph) Get(name string) (*image.Image, error) { |
| id, err := graph.idIndex.Get(name) |
| if err != nil { |
| return nil, fmt.Errorf("could not find image: %v", err) |
| } |
| img, err := graph.loadImage(id) |
| if err != nil { |
| return nil, err |
| } |
| if img.ID != id { |
| return nil, fmt.Errorf("Image stored at '%s' has wrong id '%s'", id, img.ID) |
| } |
| |
| if img.Size < 0 { |
| size, err := graph.driver.DiffSize(img.ID, img.Parent) |
| if err != nil { |
| return nil, fmt.Errorf("unable to calculate size of image id %q: %s", img.ID, err) |
| } |
| |
| img.Size = size |
| if err := graph.saveSize(graph.imageRoot(id), int(img.Size)); err != nil { |
| return nil, err |
| } |
| } |
| return img, nil |
| } |
| |
| // Create creates a new image and registers it in the graph. |
| func (graph *Graph) Create(layerData archive.ArchiveReader, containerID, containerImage, comment, author string, containerConfig, config *runconfig.Config) (*image.Image, error) { |
| img := &image.Image{ |
| ID: stringid.GenerateRandomID(), |
| Comment: comment, |
| Created: time.Now().UTC(), |
| DockerVersion: dockerversion.VERSION, |
| Author: author, |
| Config: config, |
| Architecture: runtime.GOARCH, |
| OS: runtime.GOOS, |
| } |
| |
| if containerID != "" { |
| img.Parent = containerImage |
| img.Container = containerID |
| img.ContainerConfig = *containerConfig |
| } |
| |
| if err := graph.Register(img, layerData); err != nil { |
| return nil, err |
| } |
| return img, nil |
| } |
| |
| // Register imports a pre-existing image into the graph. |
| func (graph *Graph) Register(img *image.Image, layerData archive.ArchiveReader) (err error) { |
| |
| if err := image.ValidateID(img.ID); err != nil { |
| return err |
| } |
| |
| // We need this entire operation to be atomic within the engine. Note that |
| // this doesn't mean Register is fully safe yet. |
| graph.imageMutex.Lock(img.ID) |
| defer graph.imageMutex.Unlock(img.ID) |
| |
| // The returned `error` must be named in this function's signature so that |
| // `err` is not shadowed in this deferred cleanup. |
| defer func() { |
| // If any error occurs, remove the new dir from the driver. |
| // Don't check for errors since the dir might not have been created. |
| if err != nil { |
| graph.driver.Remove(img.ID) |
| } |
| }() |
| |
| // (This is a convenience to save time. Race conditions are taken care of by os.Rename) |
| if graph.Exists(img.ID) { |
| return fmt.Errorf("Image %s already exists", img.ID) |
| } |
| |
| // Ensure that the image root does not exist on the filesystem |
| // when it is not registered in the graph. |
| // This is common when you switch from one graph driver to another |
| if err := os.RemoveAll(graph.imageRoot(img.ID)); err != nil && !os.IsNotExist(err) { |
| return err |
| } |
| |
| // If the driver has this ID but the graph doesn't, remove it from the driver to start fresh. |
| // (the graph is the source of truth). |
| // Ignore errors, since we don't know if the driver correctly returns ErrNotExist. |
| // (FIXME: make that mandatory for drivers). |
| graph.driver.Remove(img.ID) |
| |
| tmp, err := graph.mktemp("") |
| defer os.RemoveAll(tmp) |
| if err != nil { |
| return fmt.Errorf("mktemp failed: %s", err) |
| } |
| |
| // Create root filesystem in the driver |
| if err := createRootFilesystemInDriver(graph, img, layerData); err != nil { |
| return err |
| } |
| |
| // Apply the diff/layer |
| if err := graph.storeImage(img, layerData, tmp); err != nil { |
| return err |
| } |
| // Commit |
| if err := os.Rename(tmp, graph.imageRoot(img.ID)); err != nil { |
| return err |
| } |
| graph.idIndex.Add(img.ID) |
| return nil |
| } |
| |
| // TempLayerArchive creates a temporary archive of the given image's filesystem layer. |
| // The archive is stored on disk and will be automatically deleted as soon as has been read. |
| // If output is not nil, a human-readable progress bar will be written to it. |
| func (graph *Graph) TempLayerArchive(id string, sf *streamformatter.StreamFormatter, output io.Writer) (*archive.TempArchive, error) { |
| image, err := graph.Get(id) |
| if err != nil { |
| return nil, err |
| } |
| tmp, err := graph.mktemp("") |
| if err != nil { |
| return nil, err |
| } |
| a, err := graph.TarLayer(image) |
| if err != nil { |
| return nil, err |
| } |
| progressReader := progressreader.New(progressreader.Config{ |
| In: a, |
| Out: output, |
| Formatter: sf, |
| Size: 0, |
| NewLines: false, |
| ID: stringid.TruncateID(id), |
| Action: "Buffering to disk", |
| }) |
| defer progressReader.Close() |
| return archive.NewTempArchive(progressReader, tmp) |
| } |
| |
| // mktemp creates a temporary sub-directory inside the graph's filesystem. |
| func (graph *Graph) mktemp(id string) (string, error) { |
| dir := filepath.Join(graph.root, "_tmp", stringid.GenerateRandomID()) |
| if err := system.MkdirAll(dir, 0700); err != nil { |
| return "", err |
| } |
| return dir, nil |
| } |
| |
| func (graph *Graph) newTempFile() (*os.File, error) { |
| tmp, err := graph.mktemp("") |
| if err != nil { |
| return nil, err |
| } |
| return ioutil.TempFile(tmp, "") |
| } |
| |
| func bufferToFile(f *os.File, src io.Reader) (int64, digest.Digest, error) { |
| var ( |
| h = sha256.New() |
| w = gzip.NewWriter(io.MultiWriter(f, h)) |
| ) |
| _, err := io.Copy(w, src) |
| w.Close() |
| if err != nil { |
| return 0, "", err |
| } |
| n, err := f.Seek(0, os.SEEK_CUR) |
| if err != nil { |
| return 0, "", err |
| } |
| if _, err := f.Seek(0, 0); err != nil { |
| return 0, "", err |
| } |
| return n, digest.NewDigest("sha256", h), nil |
| } |
| |
| // Delete atomically removes an image from the graph. |
| func (graph *Graph) Delete(name string) error { |
| id, err := graph.idIndex.Get(name) |
| if err != nil { |
| return err |
| } |
| tmp, err := graph.mktemp("") |
| graph.idIndex.Delete(id) |
| if err == nil { |
| if err := os.Rename(graph.imageRoot(id), tmp); err != nil { |
| // On err make tmp point to old dir and cleanup unused tmp dir |
| os.RemoveAll(tmp) |
| tmp = graph.imageRoot(id) |
| } |
| } else { |
| // On err make tmp point to old dir for cleanup |
| tmp = graph.imageRoot(id) |
| } |
| // Remove rootfs data from the driver |
| graph.driver.Remove(id) |
| // Remove the trashed image directory |
| return os.RemoveAll(tmp) |
| } |
| |
| // Map returns a list of all images in the graph, addressable by ID. |
| func (graph *Graph) Map() map[string]*image.Image { |
| images := make(map[string]*image.Image) |
| graph.walkAll(func(image *image.Image) { |
| images[image.ID] = image |
| }) |
| return images |
| } |
| |
| // walkAll iterates over each image in the graph, and passes it to a handler. |
| // The walking order is undetermined. |
| func (graph *Graph) walkAll(handler func(*image.Image)) { |
| graph.idIndex.Iterate(func(id string) { |
| if img, err := graph.Get(id); err != nil { |
| return |
| } else if handler != nil { |
| handler(img) |
| } |
| }) |
| } |
| |
| // ByParent returns a lookup table of images by their parent. |
| // If an image of id ID has 3 children images, then the value for key ID |
| // will be a list of 3 images. |
| // If an image has no children, it will not have an entry in the table. |
| func (graph *Graph) ByParent() map[string][]*image.Image { |
| byParent := make(map[string][]*image.Image) |
| graph.walkAll(func(img *image.Image) { |
| parent, err := graph.Get(img.Parent) |
| if err != nil { |
| return |
| } |
| if children, exists := byParent[parent.ID]; exists { |
| byParent[parent.ID] = append(children, img) |
| } else { |
| byParent[parent.ID] = []*image.Image{img} |
| } |
| }) |
| return byParent |
| } |
| |
| // If the images and layers are in pulling chain, retain them. |
| // If not, they may be deleted by rmi with dangling condition. |
| func (graph *Graph) Retain(sessionID string, layerIDs ...string) { |
| graph.retained.Add(sessionID, layerIDs) |
| } |
| |
| // Release removes the referenced image id from the provided set of layers. |
| func (graph *Graph) Release(sessionID string, layerIDs ...string) { |
| graph.retained.Delete(sessionID, layerIDs) |
| } |
| |
| // Heads returns all heads in the graph, keyed by id. |
| // A head is an image which is not the parent of another image in the graph. |
| func (graph *Graph) Heads() map[string]*image.Image { |
| heads := make(map[string]*image.Image) |
| byParent := graph.ByParent() |
| graph.walkAll(func(image *image.Image) { |
| // If it's not in the byParent lookup table, then |
| // it's not a parent -> so it's a head! |
| if _, exists := byParent[image.ID]; !exists { |
| heads[image.ID] = image |
| } |
| }) |
| return heads |
| } |
| |
| func (graph *Graph) imageRoot(id string) string { |
| return filepath.Join(graph.root, id) |
| } |
| |
| // loadImage fetches the image with the given id from the graph. |
| func (graph *Graph) loadImage(id string) (*image.Image, error) { |
| root := graph.imageRoot(id) |
| |
| // 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.Image{} |
| dec := json.NewDecoder(jsonSource) |
| |
| // Decode the JSON data |
| if err := dec.Decode(img); err != nil { |
| return nil, err |
| } |
| if err := image.ValidateID(img.ID); err != nil { |
| return nil, err |
| } |
| |
| if buf, err := ioutil.ReadFile(filepath.Join(root, layersizeFileName)); 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 |
| } |
| |
| // saveSize stores the `size` in the provided graph `img` directory `root`. |
| func (graph *Graph) saveSize(root string, size int) error { |
| if err := ioutil.WriteFile(filepath.Join(root, layersizeFileName), []byte(strconv.Itoa(size)), 0600); err != nil { |
| return fmt.Errorf("Error storing image size in %s/%s: %s", root, layersizeFileName, err) |
| } |
| return nil |
| } |
| |
| // SetDigest sets the digest for the image layer to the provided value. |
| func (graph *Graph) SetDigest(id string, dgst digest.Digest) error { |
| root := graph.imageRoot(id) |
| if err := ioutil.WriteFile(filepath.Join(root, digestFileName), []byte(dgst.String()), 0600); err != nil { |
| return fmt.Errorf("Error storing digest in %s/%s: %s", root, digestFileName, err) |
| } |
| return nil |
| } |
| |
| // GetDigest gets the digest for the provide image layer id. |
| func (graph *Graph) GetDigest(id string) (digest.Digest, error) { |
| root := graph.imageRoot(id) |
| cs, err := ioutil.ReadFile(filepath.Join(root, digestFileName)) |
| if err != nil { |
| if os.IsNotExist(err) { |
| return "", ErrDigestNotSet |
| } |
| return "", err |
| } |
| return digest.ParseDigest(string(cs)) |
| } |
| |
| // RawJSON returns the JSON representation for an image as a byte array. |
| func (graph *Graph) RawJSON(id string) ([]byte, error) { |
| root := graph.imageRoot(id) |
| |
| buf, err := ioutil.ReadFile(jsonPath(root)) |
| if err != nil { |
| return nil, fmt.Errorf("Failed to read json for image %s: %s", id, err) |
| } |
| |
| return buf, nil |
| } |
| |
| func jsonPath(root string) string { |
| return filepath.Join(root, jsonFileName) |
| } |
| |
| func (graph *Graph) disassembleAndApplyTarLayer(img *image.Image, layerData archive.ArchiveReader, root string) error { |
| // this is saving the tar-split metadata |
| mf, err := os.OpenFile(filepath.Join(root, tarDataFileName), os.O_CREATE|os.O_WRONLY|os.O_TRUNC, os.FileMode(0600)) |
| if err != nil { |
| return err |
| } |
| mfz := gzip.NewWriter(mf) |
| metaPacker := storage.NewJSONPacker(mfz) |
| defer mf.Close() |
| defer mfz.Close() |
| |
| inflatedLayerData, err := archive.DecompressStream(layerData) |
| if err != nil { |
| return err |
| } |
| |
| // we're passing nil here for the file putter, because the ApplyDiff will |
| // handle the extraction of the archive |
| rdr, err := asm.NewInputTarStream(inflatedLayerData, metaPacker, nil) |
| if err != nil { |
| return err |
| } |
| |
| if img.Size, err = graph.driver.ApplyDiff(img.ID, img.Parent, archive.ArchiveReader(rdr)); err != nil { |
| return err |
| } |
| |
| return nil |
| } |
| |
| func (graph *Graph) assembleTarLayer(img *image.Image) (archive.Archive, error) { |
| root := graph.imageRoot(img.ID) |
| mFileName := filepath.Join(root, tarDataFileName) |
| mf, err := os.Open(mFileName) |
| if err != nil { |
| if !os.IsNotExist(err) { |
| logrus.Errorf("failed to open %q: %s", mFileName, err) |
| } |
| return nil, err |
| } |
| pR, pW := io.Pipe() |
| // this will need to be in a goroutine, as we are returning the stream of a |
| // tar archive, but can not close the metadata reader early (when this |
| // function returns)... |
| go func() { |
| defer mf.Close() |
| // let's reassemble! |
| logrus.Debugf("[graph] TarLayer with reassembly: %s", img.ID) |
| mfz, err := gzip.NewReader(mf) |
| if err != nil { |
| pW.CloseWithError(fmt.Errorf("[graph] error with %s: %s", mFileName, err)) |
| return |
| } |
| defer mfz.Close() |
| |
| // get our relative path to the container |
| fsLayer, err := graph.driver.Get(img.ID, "") |
| if err != nil { |
| pW.CloseWithError(err) |
| return |
| } |
| defer graph.driver.Put(img.ID) |
| |
| metaUnpacker := storage.NewJSONUnpacker(mfz) |
| fileGetter := storage.NewPathFileGetter(fsLayer) |
| logrus.Debugf("[graph] %s is at %q", img.ID, fsLayer) |
| ots := asm.NewOutputTarStream(fileGetter, metaUnpacker) |
| defer ots.Close() |
| if _, err := io.Copy(pW, ots); err != nil { |
| pW.CloseWithError(err) |
| return |
| } |
| pW.Close() |
| }() |
| return pR, nil |
| } |