366 lines
10 KiB
Go
366 lines
10 KiB
Go
package docker
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import (
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"fmt"
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"github.com/dotcloud/docker/archive"
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"github.com/dotcloud/docker/graphdriver"
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"github.com/dotcloud/docker/utils"
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"io"
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"io/ioutil"
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"os"
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"path"
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"path/filepath"
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"strings"
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"syscall"
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"time"
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)
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// A Graph is a store for versioned filesystem images and the relationship between them.
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type Graph struct {
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Root string
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idIndex *utils.TruncIndex
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driver graphdriver.Driver
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}
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// NewGraph instantiates a new graph at the given root path in the filesystem.
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// `root` will be created if it doesn't exist.
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func NewGraph(root string, driver graphdriver.Driver) (*Graph, error) {
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abspath, err := filepath.Abs(root)
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if err != nil {
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return nil, err
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}
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// Create the root directory if it doesn't exists
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if err := os.MkdirAll(root, 0700); err != nil && !os.IsExist(err) {
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return nil, err
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}
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graph := &Graph{
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Root: abspath,
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idIndex: utils.NewTruncIndex(),
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driver: driver,
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}
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if err := graph.restore(); err != nil {
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return nil, err
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}
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return graph, nil
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}
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func (graph *Graph) restore() error {
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dir, err := ioutil.ReadDir(graph.Root)
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if err != nil {
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return err
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}
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for _, v := range dir {
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id := v.Name()
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if graph.driver.Exists(id) {
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graph.idIndex.Add(id)
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}
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}
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return nil
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}
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// FIXME: Implement error subclass instead of looking at the error text
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// Note: This is the way golang implements os.IsNotExists on Plan9
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func (graph *Graph) IsNotExist(err error) bool {
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return err != nil && (strings.Contains(err.Error(), "does not exist") || strings.Contains(err.Error(), "No such"))
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}
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// Exists returns true if an image is registered at the given id.
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// If the image doesn't exist or if an error is encountered, false is returned.
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func (graph *Graph) Exists(id string) bool {
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if _, err := graph.Get(id); err != nil {
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return false
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}
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return true
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}
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// Get returns the image with the given id, or an error if the image doesn't exist.
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func (graph *Graph) Get(name string) (*Image, error) {
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id, err := graph.idIndex.Get(name)
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if err != nil {
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return nil, err
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}
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// FIXME: return nil when the image doesn't exist, instead of an error
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img, err := LoadImage(graph.imageRoot(id))
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if err != nil {
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return nil, err
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}
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// Check that the filesystem layer exists
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rootfs, err := graph.driver.Get(img.ID)
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if err != nil {
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return nil, fmt.Errorf("Driver %s failed to get image rootfs %s: %s", graph.driver, img.ID, err)
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}
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if img.ID != id {
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return nil, fmt.Errorf("Image stored at '%s' has wrong id '%s'", id, img.ID)
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}
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img.graph = graph
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if img.Size == 0 {
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size, err := utils.TreeSize(rootfs)
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if err != nil {
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return nil, fmt.Errorf("Error computing size of rootfs %s: %s", img.ID, err)
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}
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img.Size = size
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if err := img.SaveSize(graph.imageRoot(id)); err != nil {
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return nil, err
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}
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}
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return img, nil
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}
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// Create creates a new image and registers it in the graph.
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func (graph *Graph) Create(layerData archive.Archive, container *Container, comment, author string, config *Config) (*Image, error) {
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img := &Image{
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ID: GenerateID(),
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Comment: comment,
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Created: time.Now().UTC(),
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DockerVersion: VERSION,
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Author: author,
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Config: config,
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Architecture: "x86_64",
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}
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if container != nil {
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img.Parent = container.Image
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img.Container = container.ID
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img.ContainerConfig = *container.Config
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}
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if err := graph.Register(nil, layerData, img); err != nil {
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return nil, err
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}
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return img, nil
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}
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// Register imports a pre-existing image into the graph.
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// FIXME: pass img as first argument
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func (graph *Graph) Register(jsonData []byte, layerData archive.Archive, img *Image) error {
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if err := ValidateID(img.ID); err != nil {
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return err
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}
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// (This is a convenience to save time. Race conditions are taken care of by os.Rename)
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if graph.Exists(img.ID) {
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return fmt.Errorf("Image %s already exists", img.ID)
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}
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// Ensure that the image root does not exist on the filesystem
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// when it is not registered in the graph.
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// This is common when you switch from one graph driver to another
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if err := os.RemoveAll(graph.imageRoot(img.ID)); err != nil && !os.IsNotExist(err) {
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return err
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}
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tmp, err := graph.Mktemp("")
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defer os.RemoveAll(tmp)
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if err != nil {
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return fmt.Errorf("Mktemp failed: %s", err)
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}
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// Create root filesystem in the driver
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if err := graph.driver.Create(img.ID, img.Parent); err != nil {
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return fmt.Errorf("Driver %s failed to create image rootfs %s: %s", graph.driver, img.ID, err)
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}
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// Mount the root filesystem so we can apply the diff/layer
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rootfs, err := graph.driver.Get(img.ID)
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if err != nil {
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return fmt.Errorf("Driver %s failed to get image rootfs %s: %s", graph.driver, img.ID, err)
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}
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img.graph = graph
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if err := StoreImage(img, jsonData, layerData, tmp, rootfs); err != nil {
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return err
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}
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// Commit
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if err := os.Rename(tmp, graph.imageRoot(img.ID)); err != nil {
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return err
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}
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graph.idIndex.Add(img.ID)
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return nil
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}
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// TempLayerArchive creates a temporary archive of the given image's filesystem layer.
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// The archive is stored on disk and will be automatically deleted as soon as has been read.
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// If output is not nil, a human-readable progress bar will be written to it.
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// FIXME: does this belong in Graph? How about MktempFile, let the caller use it for archives?
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func (graph *Graph) TempLayerArchive(id string, compression archive.Compression, sf *utils.StreamFormatter, output io.Writer) (*archive.TempArchive, error) {
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image, err := graph.Get(id)
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if err != nil {
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return nil, err
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}
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tmp, err := graph.Mktemp("")
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if err != nil {
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return nil, err
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}
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a, err := image.TarLayer()
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if err != nil {
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return nil, err
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}
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return archive.NewTempArchive(utils.ProgressReader(ioutil.NopCloser(a), 0, output, sf.FormatProgress("", "Buffering to disk", "%v/%v (%v)"), sf, true), tmp)
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}
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// Mktemp creates a temporary sub-directory inside the graph's filesystem.
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func (graph *Graph) Mktemp(id string) (string, error) {
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dir := path.Join(graph.Root, "_tmp", GenerateID())
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if err := os.MkdirAll(dir, 0700); err != nil {
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return "", err
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}
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return dir, nil
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}
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// setupInitLayer populates a directory with mountpoints suitable
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// for bind-mounting dockerinit into the container. The mountpoint is simply an
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// empty file at /.dockerinit
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//
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// This extra layer is used by all containers as the top-most ro layer. It protects
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// the container from unwanted side-effects on the rw layer.
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func setupInitLayer(initLayer string) error {
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for pth, typ := range map[string]string{
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"/dev/pts": "dir",
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"/dev/shm": "dir",
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"/proc": "dir",
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"/sys": "dir",
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"/.dockerinit": "file",
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"/.dockerenv": "file",
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"/etc/resolv.conf": "file",
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"/etc/hosts": "file",
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"/etc/hostname": "file",
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// "var/run": "dir",
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// "var/lock": "dir",
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} {
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parts := strings.Split(pth, "/")
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prev := "/"
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for _, p := range parts[1:] {
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prev = path.Join(prev, p)
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syscall.Unlink(path.Join(initLayer, prev))
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}
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if _, err := os.Stat(path.Join(initLayer, pth)); err != nil {
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if os.IsNotExist(err) {
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switch typ {
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case "dir":
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if err := os.MkdirAll(path.Join(initLayer, pth), 0755); err != nil {
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return err
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}
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case "file":
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if err := os.MkdirAll(path.Join(initLayer, path.Dir(pth)), 0755); err != nil {
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return err
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}
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f, err := os.OpenFile(path.Join(initLayer, pth), os.O_CREATE, 0755)
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if err != nil {
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return err
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}
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f.Close()
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}
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} else {
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return err
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}
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}
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}
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// Layer is ready to use, if it wasn't before.
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return nil
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}
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// Check if given error is "not empty".
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// Note: this is the way golang does it internally with os.IsNotExists.
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func isNotEmpty(err error) bool {
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switch pe := err.(type) {
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case nil:
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return false
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case *os.PathError:
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err = pe.Err
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case *os.LinkError:
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err = pe.Err
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}
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return strings.Contains(err.Error(), " not empty")
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}
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// Delete atomically removes an image from the graph.
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func (graph *Graph) Delete(name string) error {
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id, err := graph.idIndex.Get(name)
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if err != nil {
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return err
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}
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tmp, err := graph.Mktemp("")
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if err != nil {
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return err
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}
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graph.idIndex.Delete(id)
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err = os.Rename(graph.imageRoot(id), tmp)
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if err != nil {
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return err
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}
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// Remove rootfs data from the driver
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graph.driver.Remove(id)
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// Remove the trashed image directory
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return os.RemoveAll(tmp)
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}
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// Map returns a list of all images in the graph, addressable by ID.
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func (graph *Graph) Map() (map[string]*Image, error) {
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images := make(map[string]*Image)
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err := graph.walkAll(func(image *Image) {
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images[image.ID] = image
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})
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if err != nil {
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return nil, err
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}
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return images, nil
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}
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// walkAll iterates over each image in the graph, and passes it to a handler.
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// The walking order is undetermined.
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func (graph *Graph) walkAll(handler func(*Image)) error {
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files, err := ioutil.ReadDir(graph.Root)
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if err != nil {
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return err
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}
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for _, st := range files {
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if img, err := graph.Get(st.Name()); err != nil {
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// Skip image
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continue
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} else if handler != nil {
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handler(img)
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}
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}
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return nil
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}
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// ByParent returns a lookup table of images by their parent.
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// If an image of id ID has 3 children images, then the value for key ID
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// will be a list of 3 images.
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// If an image has no children, it will not have an entry in the table.
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func (graph *Graph) ByParent() (map[string][]*Image, error) {
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byParent := make(map[string][]*Image)
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err := graph.walkAll(func(image *Image) {
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parent, err := graph.Get(image.Parent)
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if err != nil {
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return
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}
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if children, exists := byParent[parent.ID]; exists {
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byParent[parent.ID] = append(children, image)
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} else {
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byParent[parent.ID] = []*Image{image}
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}
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})
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return byParent, err
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}
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// Heads returns all heads in the graph, keyed by id.
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// A head is an image which is not the parent of another image in the graph.
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func (graph *Graph) Heads() (map[string]*Image, error) {
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heads := make(map[string]*Image)
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byParent, err := graph.ByParent()
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if err != nil {
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return nil, err
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}
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err = graph.walkAll(func(image *Image) {
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// If it's not in the byParent lookup table, then
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// it's not a parent -> so it's a head!
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if _, exists := byParent[image.ID]; !exists {
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heads[image.ID] = image
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}
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})
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return heads, err
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}
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func (graph *Graph) imageRoot(id string) string {
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return path.Join(graph.Root, id)
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}
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