mirror of
https://github.com/moby/moby.git
synced 2022-11-09 12:21:53 -05:00
421 lines
11 KiB
Go
421 lines
11 KiB
Go
package tarexport // import "github.com/docker/docker/image/tarexport"
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import (
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"encoding/json"
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"fmt"
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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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"runtime"
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"time"
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"github.com/docker/distribution"
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"github.com/docker/distribution/reference"
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"github.com/docker/docker/image"
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v1 "github.com/docker/docker/image/v1"
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"github.com/docker/docker/layer"
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"github.com/docker/docker/pkg/archive"
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"github.com/docker/docker/pkg/system"
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digest "github.com/opencontainers/go-digest"
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"github.com/pkg/errors"
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)
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type imageDescriptor struct {
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refs []reference.NamedTagged
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layers []string
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image *image.Image
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layerRef layer.Layer
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}
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type saveSession struct {
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*tarexporter
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outDir string
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images map[image.ID]*imageDescriptor
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savedLayers map[string]struct{}
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diffIDPaths map[layer.DiffID]string // cache every diffID blob to avoid duplicates
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}
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func (l *tarexporter) Save(names []string, outStream io.Writer) error {
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images, err := l.parseNames(names)
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if err != nil {
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return err
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}
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// Release all the image top layer references
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defer l.releaseLayerReferences(images)
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return (&saveSession{tarexporter: l, images: images}).save(outStream)
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}
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// parseNames will parse the image names to a map which contains image.ID to *imageDescriptor.
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// Each imageDescriptor holds an image top layer reference named 'layerRef'. It is taken here, should be released later.
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func (l *tarexporter) parseNames(names []string) (desc map[image.ID]*imageDescriptor, rErr error) {
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imgDescr := make(map[image.ID]*imageDescriptor)
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defer func() {
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if rErr != nil {
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l.releaseLayerReferences(imgDescr)
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}
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}()
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addAssoc := func(id image.ID, ref reference.Named) error {
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if _, ok := imgDescr[id]; !ok {
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descr := &imageDescriptor{}
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if err := l.takeLayerReference(id, descr); err != nil {
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return err
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}
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imgDescr[id] = descr
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}
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if ref != nil {
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if _, ok := ref.(reference.Canonical); ok {
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return nil
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}
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tagged, ok := reference.TagNameOnly(ref).(reference.NamedTagged)
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if !ok {
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return nil
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}
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for _, t := range imgDescr[id].refs {
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if tagged.String() == t.String() {
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return nil
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}
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}
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imgDescr[id].refs = append(imgDescr[id].refs, tagged)
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}
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return nil
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}
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for _, name := range names {
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ref, err := reference.ParseAnyReference(name)
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if err != nil {
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return nil, err
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}
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namedRef, ok := ref.(reference.Named)
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if !ok {
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// Check if digest ID reference
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if digested, ok := ref.(reference.Digested); ok {
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id := image.IDFromDigest(digested.Digest())
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if err := addAssoc(id, nil); err != nil {
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return nil, err
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}
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continue
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}
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return nil, errors.Errorf("invalid reference: %v", name)
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}
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if reference.FamiliarName(namedRef) == string(digest.Canonical) {
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imgID, err := l.is.Search(name)
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if err != nil {
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return nil, err
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}
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if err := addAssoc(imgID, nil); err != nil {
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return nil, err
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}
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continue
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}
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if reference.IsNameOnly(namedRef) {
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assocs := l.rs.ReferencesByName(namedRef)
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for _, assoc := range assocs {
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if err := addAssoc(image.IDFromDigest(assoc.ID), assoc.Ref); err != nil {
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return nil, err
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}
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}
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if len(assocs) == 0 {
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imgID, err := l.is.Search(name)
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if err != nil {
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return nil, err
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}
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if err := addAssoc(imgID, nil); err != nil {
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return nil, err
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}
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}
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continue
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}
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id, err := l.rs.Get(namedRef)
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if err != nil {
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return nil, err
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}
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if err := addAssoc(image.IDFromDigest(id), namedRef); err != nil {
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return nil, err
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}
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}
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return imgDescr, nil
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}
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// takeLayerReference will take/Get the image top layer reference
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func (l *tarexporter) takeLayerReference(id image.ID, imgDescr *imageDescriptor) error {
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img, err := l.is.Get(id)
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if err != nil {
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return err
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}
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imgDescr.image = img
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topLayerID := img.RootFS.ChainID()
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if topLayerID == "" {
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return nil
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}
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os := img.OS
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if os == "" {
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os = runtime.GOOS
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}
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if !system.IsOSSupported(os) {
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return fmt.Errorf("os %q is not supported", os)
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}
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layer, err := l.lss.Get(topLayerID)
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if err != nil {
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return err
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}
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imgDescr.layerRef = layer
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return nil
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}
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// releaseLayerReferences will release all the image top layer references
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func (l *tarexporter) releaseLayerReferences(imgDescr map[image.ID]*imageDescriptor) error {
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for _, descr := range imgDescr {
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if descr.layerRef != nil {
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l.lss.Release(descr.layerRef)
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}
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}
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return nil
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}
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func (s *saveSession) save(outStream io.Writer) error {
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s.savedLayers = make(map[string]struct{})
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s.diffIDPaths = make(map[layer.DiffID]string)
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// get image json
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tempDir, err := ioutil.TempDir("", "docker-export-")
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if err != nil {
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return err
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}
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defer os.RemoveAll(tempDir)
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s.outDir = tempDir
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reposLegacy := make(map[string]map[string]string)
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var manifest []manifestItem
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var parentLinks []parentLink
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for id, imageDescr := range s.images {
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foreignSrcs, err := s.saveImage(id)
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if err != nil {
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return err
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}
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var repoTags []string
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var layers []string
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for _, ref := range imageDescr.refs {
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familiarName := reference.FamiliarName(ref)
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if _, ok := reposLegacy[familiarName]; !ok {
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reposLegacy[familiarName] = make(map[string]string)
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}
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reposLegacy[familiarName][ref.Tag()] = imageDescr.layers[len(imageDescr.layers)-1]
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repoTags = append(repoTags, reference.FamiliarString(ref))
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}
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for _, l := range imageDescr.layers {
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// IMPORTANT: We use path, not filepath here to ensure the layers
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// in the manifest use Unix-style forward-slashes.
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layers = append(layers, path.Join(l, legacyLayerFileName))
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}
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manifest = append(manifest, manifestItem{
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Config: id.Digest().Hex() + ".json",
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RepoTags: repoTags,
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Layers: layers,
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LayerSources: foreignSrcs,
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})
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parentID, _ := s.is.GetParent(id)
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parentLinks = append(parentLinks, parentLink{id, parentID})
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s.tarexporter.loggerImgEvent.LogImageEvent(id.String(), id.String(), "save")
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}
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for i, p := range validatedParentLinks(parentLinks) {
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if p.parentID != "" {
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manifest[i].Parent = p.parentID
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}
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}
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if len(reposLegacy) > 0 {
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reposFile := filepath.Join(tempDir, legacyRepositoriesFileName)
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rf, err := os.OpenFile(reposFile, os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0644)
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if err != nil {
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return err
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}
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if err := json.NewEncoder(rf).Encode(reposLegacy); err != nil {
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rf.Close()
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return err
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}
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rf.Close()
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if err := system.Chtimes(reposFile, time.Unix(0, 0), time.Unix(0, 0)); err != nil {
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return err
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}
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}
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manifestFileName := filepath.Join(tempDir, manifestFileName)
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f, err := os.OpenFile(manifestFileName, os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0644)
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if err != nil {
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return err
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}
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if err := json.NewEncoder(f).Encode(manifest); err != nil {
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f.Close()
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return err
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}
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f.Close()
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if err := system.Chtimes(manifestFileName, time.Unix(0, 0), time.Unix(0, 0)); err != nil {
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return err
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}
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fs, err := archive.Tar(tempDir, archive.Uncompressed)
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if err != nil {
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return err
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}
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defer fs.Close()
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_, err = io.Copy(outStream, fs)
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return err
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}
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func (s *saveSession) saveImage(id image.ID) (map[layer.DiffID]distribution.Descriptor, error) {
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img := s.images[id].image
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if len(img.RootFS.DiffIDs) == 0 {
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return nil, fmt.Errorf("empty export - not implemented")
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}
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var parent digest.Digest
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var layers []string
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var foreignSrcs map[layer.DiffID]distribution.Descriptor
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for i := range img.RootFS.DiffIDs {
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v1Img := image.V1Image{
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// This is for backward compatibility used for
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// pre v1.9 docker.
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Created: time.Unix(0, 0),
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}
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if i == len(img.RootFS.DiffIDs)-1 {
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v1Img = img.V1Image
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}
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rootFS := *img.RootFS
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rootFS.DiffIDs = rootFS.DiffIDs[:i+1]
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v1ID, err := v1.CreateID(v1Img, rootFS.ChainID(), parent)
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if err != nil {
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return nil, err
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}
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v1Img.ID = v1ID.Hex()
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if parent != "" {
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v1Img.Parent = parent.Hex()
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}
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v1Img.OS = img.OS
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src, err := s.saveLayer(rootFS.ChainID(), v1Img, img.Created)
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if err != nil {
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return nil, err
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}
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layers = append(layers, v1Img.ID)
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parent = v1ID
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if src.Digest != "" {
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if foreignSrcs == nil {
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foreignSrcs = make(map[layer.DiffID]distribution.Descriptor)
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}
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foreignSrcs[img.RootFS.DiffIDs[i]] = src
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}
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}
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configFile := filepath.Join(s.outDir, id.Digest().Hex()+".json")
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if err := ioutil.WriteFile(configFile, img.RawJSON(), 0644); err != nil {
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return nil, err
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}
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if err := system.Chtimes(configFile, img.Created, img.Created); err != nil {
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return nil, err
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}
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s.images[id].layers = layers
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return foreignSrcs, nil
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}
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func (s *saveSession) saveLayer(id layer.ChainID, legacyImg image.V1Image, createdTime time.Time) (distribution.Descriptor, error) {
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if _, exists := s.savedLayers[legacyImg.ID]; exists {
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return distribution.Descriptor{}, nil
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}
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outDir := filepath.Join(s.outDir, legacyImg.ID)
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if err := os.Mkdir(outDir, 0755); err != nil {
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return distribution.Descriptor{}, err
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}
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// todo: why is this version file here?
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if err := ioutil.WriteFile(filepath.Join(outDir, legacyVersionFileName), []byte("1.0"), 0644); err != nil {
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return distribution.Descriptor{}, err
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}
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imageConfig, err := json.Marshal(legacyImg)
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if err != nil {
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return distribution.Descriptor{}, err
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}
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if err := ioutil.WriteFile(filepath.Join(outDir, legacyConfigFileName), imageConfig, 0644); err != nil {
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return distribution.Descriptor{}, err
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}
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// serialize filesystem
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layerPath := filepath.Join(outDir, legacyLayerFileName)
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l, err := s.lss.Get(id)
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if err != nil {
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return distribution.Descriptor{}, err
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}
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defer layer.ReleaseAndLog(s.lss, l)
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if oldPath, exists := s.diffIDPaths[l.DiffID()]; exists {
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relPath, err := filepath.Rel(outDir, oldPath)
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if err != nil {
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return distribution.Descriptor{}, err
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}
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if err := os.Symlink(relPath, layerPath); err != nil {
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return distribution.Descriptor{}, errors.Wrap(err, "error creating symlink while saving layer")
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}
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} else {
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// Use system.CreateSequential rather than os.Create. This ensures sequential
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// file access on Windows to avoid eating into MM standby list.
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// On Linux, this equates to a regular os.Create.
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tarFile, err := system.CreateSequential(layerPath)
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if err != nil {
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return distribution.Descriptor{}, err
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}
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defer tarFile.Close()
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arch, err := l.TarStream()
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if err != nil {
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return distribution.Descriptor{}, err
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}
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defer arch.Close()
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if _, err := io.Copy(tarFile, arch); err != nil {
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return distribution.Descriptor{}, err
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}
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for _, fname := range []string{"", legacyVersionFileName, legacyConfigFileName, legacyLayerFileName} {
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// todo: maybe save layer created timestamp?
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if err := system.Chtimes(filepath.Join(outDir, fname), createdTime, createdTime); err != nil {
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return distribution.Descriptor{}, err
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}
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}
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s.diffIDPaths[l.DiffID()] = layerPath
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}
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s.savedLayers[legacyImg.ID] = struct{}{}
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var src distribution.Descriptor
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if fs, ok := l.(distribution.Describable); ok {
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src = fs.Descriptor()
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}
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return src, nil
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}
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