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pull_v2.go
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pull_v2.go
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package graph
import (
"encoding/json"
"errors"
"fmt"
"io"
"io/ioutil"
"os"
"github.com/Sirupsen/logrus"
"github.com/docker/distribution"
"github.com/docker/distribution/digest"
"github.com/docker/distribution/manifest"
"github.com/docker/docker/image"
"github.com/docker/docker/pkg/broadcaster"
"github.com/docker/docker/pkg/progressreader"
"github.com/docker/docker/pkg/streamformatter"
"github.com/docker/docker/pkg/stringid"
"github.com/docker/docker/registry"
"github.com/docker/docker/utils"
"golang.org/x/net/context"
)
type v2Puller struct {
*TagStore
endpoint registry.APIEndpoint
config *ImagePullConfig
sf *streamformatter.StreamFormatter
repoInfo *registry.RepositoryInfo
repo distribution.Repository
sessionID string
}
func (p *v2Puller) Pull(tag string) (fallback bool, err error) {
// TODO(tiborvass): was ReceiveTimeout
p.repo, err = NewV2Repository(p.repoInfo, p.endpoint, p.config.MetaHeaders, p.config.AuthConfig, "pull")
if err != nil {
logrus.Warnf("Error getting v2 registry: %v", err)
return true, err
}
p.sessionID = stringid.GenerateRandomID()
if err := p.pullV2Repository(tag); err != nil {
if registry.ContinueOnError(err) {
logrus.Debugf("Error trying v2 registry: %v", err)
return true, err
}
return false, err
}
return false, nil
}
func (p *v2Puller) pullV2Repository(tag string) (err error) {
var tags []string
taggedName := p.repoInfo.LocalName
if len(tag) > 0 {
tags = []string{tag}
taggedName = utils.ImageReference(p.repoInfo.LocalName, tag)
} else {
var err error
manSvc, err := p.repo.Manifests(context.Background())
if err != nil {
return err
}
tags, err = manSvc.Tags()
if err != nil {
return err
}
}
poolKey := "v2:" + taggedName
broadcaster, found := p.poolAdd("pull", poolKey)
broadcaster.Add(p.config.OutStream)
if found {
// Another pull of the same repository is already taking place; just wait for it to finish
return broadcaster.Wait()
}
// This must use a closure so it captures the value of err when the
// function returns, not when the 'defer' is evaluated.
defer func() {
p.poolRemoveWithError("pull", poolKey, err)
}()
var layersDownloaded bool
for _, tag := range tags {
// pulledNew is true if either new layers were downloaded OR if existing images were newly tagged
// TODO(tiborvass): should we change the name of `layersDownload`? What about message in WriteStatus?
pulledNew, err := p.pullV2Tag(broadcaster, tag, taggedName)
if err != nil {
return err
}
layersDownloaded = layersDownloaded || pulledNew
}
writeStatus(taggedName, broadcaster, p.sf, layersDownloaded)
return nil
}
// downloadInfo is used to pass information from download to extractor
type downloadInfo struct {
img contentAddressableDescriptor
imgIndex int
tmpFile *os.File
digest digest.Digest
layer distribution.ReadSeekCloser
size int64
err chan error
poolKey string
broadcaster *broadcaster.Buffered
}
// contentAddressableDescriptor is used to pass image data from a manifest to the
// graph.
type contentAddressableDescriptor struct {
id string
parent string
strongID digest.Digest
compatibilityID string
config []byte
v1Compatibility []byte
}
func newContentAddressableImage(v1Compatibility []byte, blobSum digest.Digest, parent digest.Digest) (contentAddressableDescriptor, error) {
img := contentAddressableDescriptor{
v1Compatibility: v1Compatibility,
}
var err error
img.config, err = image.MakeImageConfig(v1Compatibility, blobSum, parent)
if err != nil {
return img, err
}
img.strongID, err = image.StrongID(img.config)
if err != nil {
return img, err
}
unmarshalledConfig, err := image.NewImgJSON(v1Compatibility)
if err != nil {
return img, err
}
img.compatibilityID = unmarshalledConfig.ID
img.id = img.strongID.Hex()
return img, nil
}
// ID returns the actual ID to be used for the downloaded image. This may be
// a computed ID.
func (img contentAddressableDescriptor) ID() string {
return img.id
}
// Parent returns the parent ID to be used for the image. This may be a
// computed ID.
func (img contentAddressableDescriptor) Parent() string {
return img.parent
}
// MarshalConfig renders the image structure into JSON.
func (img contentAddressableDescriptor) MarshalConfig() ([]byte, error) {
return img.config, nil
}
type errVerification struct{}
func (errVerification) Error() string { return "verification failed" }
func (p *v2Puller) download(di *downloadInfo) {
logrus.Debugf("pulling blob %q to %s", di.digest, di.img.id)
blobs := p.repo.Blobs(context.Background())
desc, err := blobs.Stat(context.Background(), di.digest)
if err != nil {
logrus.Debugf("Error statting layer: %v", err)
di.err <- err
return
}
di.size = desc.Size
layerDownload, err := blobs.Open(context.Background(), di.digest)
if err != nil {
logrus.Debugf("Error fetching layer: %v", err)
di.err <- err
return
}
defer layerDownload.Close()
verifier, err := digest.NewDigestVerifier(di.digest)
if err != nil {
di.err <- err
return
}
reader := progressreader.New(progressreader.Config{
In: ioutil.NopCloser(io.TeeReader(layerDownload, verifier)),
Out: di.broadcaster,
Formatter: p.sf,
Size: di.size,
NewLines: false,
ID: stringid.TruncateID(di.img.id),
Action: "Downloading",
})
io.Copy(di.tmpFile, reader)
di.broadcaster.Write(p.sf.FormatProgress(stringid.TruncateID(di.img.id), "Verifying Checksum", nil))
if !verifier.Verified() {
err = fmt.Errorf("filesystem layer verification failed for digest %s", di.digest)
logrus.Error(err)
di.err <- err
return
}
di.broadcaster.Write(p.sf.FormatProgress(stringid.TruncateID(di.img.id), "Download complete", nil))
logrus.Debugf("Downloaded %s to tempfile %s", di.img.id, di.tmpFile.Name())
di.layer = layerDownload
di.err <- nil
}
func (p *v2Puller) pullV2Tag(out io.Writer, tag, taggedName string) (tagUpdated bool, err error) {
logrus.Debugf("Pulling tag from V2 registry: %q", tag)
manSvc, err := p.repo.Manifests(context.Background())
if err != nil {
return false, err
}
unverifiedManifest, err := manSvc.GetByTag(tag)
if err != nil {
return false, err
}
if unverifiedManifest == nil {
return false, fmt.Errorf("image manifest does not exist for tag %q", tag)
}
var verifiedManifest *manifest.Manifest
verifiedManifest, err = verifyManifest(unverifiedManifest, tag)
if err != nil {
return false, err
}
// remove duplicate layers and check parent chain validity
err = fixManifestLayers(verifiedManifest)
if err != nil {
return false, err
}
imgs, err := p.getImageInfos(verifiedManifest)
if err != nil {
return false, err
}
out.Write(p.sf.FormatStatus(tag, "Pulling from %s", p.repo.Name()))
var downloads []*downloadInfo
var layerIDs []string
defer func() {
p.graph.Release(p.sessionID, layerIDs...)
for _, d := range downloads {
p.poolRemoveWithError("pull", d.poolKey, err)
if d.tmpFile != nil {
d.tmpFile.Close()
if err := os.RemoveAll(d.tmpFile.Name()); err != nil {
logrus.Errorf("Failed to remove temp file: %s", d.tmpFile.Name())
}
}
}
}()
for i := len(verifiedManifest.FSLayers) - 1; i >= 0; i-- {
img := imgs[i]
p.graph.Retain(p.sessionID, img.id)
layerIDs = append(layerIDs, img.id)
p.graph.imageMutex.Lock(img.id)
// Check if exists
if p.graph.Exists(img.id) {
if err := p.validateImageInGraph(img.id, imgs, i); err != nil {
p.graph.imageMutex.Unlock(img.id)
return false, fmt.Errorf("image validation failed: %v", err)
}
logrus.Debugf("Image already exists: %s", img.id)
p.graph.imageMutex.Unlock(img.id)
continue
}
p.graph.imageMutex.Unlock(img.id)
out.Write(p.sf.FormatProgress(stringid.TruncateID(img.id), "Pulling fs layer", nil))
d := &downloadInfo{
img: img,
imgIndex: i,
poolKey: "v2layer:" + img.id,
digest: verifiedManifest.FSLayers[i].BlobSum,
// TODO: seems like this chan buffer solved hanging problem in go1.5,
// this can indicate some deeper problem that somehow we never take
// error from channel in loop below
err: make(chan error, 1),
}
tmpFile, err := ioutil.TempFile("", "GetImageBlob")
if err != nil {
return false, err
}
d.tmpFile = tmpFile
downloads = append(downloads, d)
broadcaster, found := p.poolAdd("pull", d.poolKey)
broadcaster.Add(out)
d.broadcaster = broadcaster
if found {
d.err <- nil
} else {
go p.download(d)
}
}
for _, d := range downloads {
if err := <-d.err; err != nil {
return false, err
}
if d.layer == nil {
// Wait for a different pull to download and extract
// this layer.
err = d.broadcaster.Wait()
if err != nil {
return false, err
}
continue
}
d.tmpFile.Seek(0, 0)
err := func() error {
reader := progressreader.New(progressreader.Config{
In: d.tmpFile,
Out: d.broadcaster,
Formatter: p.sf,
Size: d.size,
NewLines: false,
ID: stringid.TruncateID(d.img.id),
Action: "Extracting",
})
p.graph.imagesMutex.Lock()
defer p.graph.imagesMutex.Unlock()
p.graph.imageMutex.Lock(d.img.id)
defer p.graph.imageMutex.Unlock(d.img.id)
// Must recheck the data on disk if any exists.
// This protects against races where something
// else is written to the graph under this ID
// after attemptIDReuse.
if p.graph.Exists(d.img.id) {
if err := p.validateImageInGraph(d.img.id, imgs, d.imgIndex); err != nil {
return fmt.Errorf("image validation failed: %v", err)
}
}
if err := p.graph.register(d.img, reader); err != nil {
return err
}
if err := p.graph.setLayerDigest(d.img.id, d.digest); err != nil {
return err
}
if err := p.graph.setV1CompatibilityConfig(d.img.id, d.img.v1Compatibility); err != nil {
return err
}
return nil
}()
if err != nil {
return false, err
}
d.broadcaster.Write(p.sf.FormatProgress(stringid.TruncateID(d.img.id), "Pull complete", nil))
d.broadcaster.Close()
tagUpdated = true
}
manifestDigest, _, err := digestFromManifest(unverifiedManifest, p.repoInfo.LocalName)
if err != nil {
return false, err
}
// Check for new tag if no layers downloaded
if !tagUpdated {
repo, err := p.Get(p.repoInfo.LocalName)
if err != nil {
return false, err
}
if repo != nil {
if _, exists := repo[tag]; !exists {
tagUpdated = true
}
} else {
tagUpdated = true
}
}
firstID := layerIDs[len(layerIDs)-1]
if utils.DigestReference(tag) {
// TODO(stevvooe): Ideally, we should always set the digest so we can
// use the digest whether we pull by it or not. Unfortunately, the tag
// store treats the digest as a separate tag, meaning there may be an
// untagged digest image that would seem to be dangling by a user.
if err = p.SetDigest(p.repoInfo.LocalName, tag, firstID); err != nil {
return false, err
}
} else {
// only set the repository/tag -> image ID mapping when pulling by tag (i.e. not by digest)
if err = p.Tag(p.repoInfo.LocalName, tag, firstID, true); err != nil {
return false, err
}
}
if manifestDigest != "" {
out.Write(p.sf.FormatStatus("", "Digest: %s", manifestDigest))
}
return tagUpdated, nil
}
func verifyManifest(signedManifest *manifest.SignedManifest, tag string) (m *manifest.Manifest, err error) {
// If pull by digest, then verify the manifest digest. NOTE: It is
// important to do this first, before any other content validation. If the
// digest cannot be verified, don't even bother with those other things.
if manifestDigest, err := digest.ParseDigest(tag); err == nil {
verifier, err := digest.NewDigestVerifier(manifestDigest)
if err != nil {
return nil, err
}
payload, err := signedManifest.Payload()
if err != nil {
// If this failed, the signatures section was corrupted
// or missing. Treat the entire manifest as the payload.
payload = signedManifest.Raw
}
if _, err := verifier.Write(payload); err != nil {
return nil, err
}
if !verifier.Verified() {
err := fmt.Errorf("image verification failed for digest %s", manifestDigest)
logrus.Error(err)
return nil, err
}
var verifiedManifest manifest.Manifest
if err = json.Unmarshal(payload, &verifiedManifest); err != nil {
return nil, err
}
m = &verifiedManifest
} else {
m = &signedManifest.Manifest
}
if m.SchemaVersion != 1 {
return nil, fmt.Errorf("unsupported schema version %d for tag %q", m.SchemaVersion, tag)
}
if len(m.FSLayers) != len(m.History) {
return nil, fmt.Errorf("length of history not equal to number of layers for tag %q", tag)
}
if len(m.FSLayers) == 0 {
return nil, fmt.Errorf("no FSLayers in manifest for tag %q", tag)
}
return m, nil
}
// fixManifestLayers removes repeated layers from the manifest and checks the
// correctness of the parent chain.
func fixManifestLayers(m *manifest.Manifest) error {
images := make([]*image.Image, len(m.FSLayers))
for i := range m.FSLayers {
img, err := image.NewImgJSON([]byte(m.History[i].V1Compatibility))
if err != nil {
return err
}
images[i] = img
if err := image.ValidateID(img.ID); err != nil {
return err
}
}
if images[len(images)-1].Parent != "" {
return errors.New("Invalid parent ID in the base layer of the image.")
}
// check general duplicates to error instead of a deadlock
idmap := make(map[string]struct{})
var lastID string
for _, img := range images {
// skip IDs that appear after each other, we handle those later
if _, exists := idmap[img.ID]; img.ID != lastID && exists {
return fmt.Errorf("ID %+v appears multiple times in manifest", img.ID)
}
lastID = img.ID
idmap[lastID] = struct{}{}
}
// backwards loop so that we keep the remaining indexes after removing items
for i := len(images) - 2; i >= 0; i-- {
if images[i].ID == images[i+1].ID { // repeated ID. remove and continue
m.FSLayers = append(m.FSLayers[:i], m.FSLayers[i+1:]...)
m.History = append(m.History[:i], m.History[i+1:]...)
} else if images[i].Parent != images[i+1].ID {
return fmt.Errorf("Invalid parent ID. Expected %v, got %v.", images[i+1].ID, images[i].Parent)
}
}
return nil
}
// getImageInfos returns an imageinfo struct for every image in the manifest.
// These objects contain both calculated strongIDs and compatibilityIDs found
// in v1Compatibility object.
func (p *v2Puller) getImageInfos(m *manifest.Manifest) ([]contentAddressableDescriptor, error) {
imgs := make([]contentAddressableDescriptor, len(m.FSLayers))
var parent digest.Digest
for i := len(imgs) - 1; i >= 0; i-- {
var err error
imgs[i], err = newContentAddressableImage([]byte(m.History[i].V1Compatibility), m.FSLayers[i].BlobSum, parent)
if err != nil {
return nil, err
}
parent = imgs[i].strongID
}
p.attemptIDReuse(imgs)
return imgs, nil
}
// attemptIDReuse does a best attempt to match verified compatibilityIDs
// already in the graph with the computed strongIDs so we can keep using them.
// This process will never fail but may just return the strongIDs if none of
// the compatibilityIDs exists or can be verified. If the strongIDs themselves
// fail verification, we deterministically generate alternate IDs to use until
// we find one that's available or already exists with the correct data.
func (p *v2Puller) attemptIDReuse(imgs []contentAddressableDescriptor) {
// This function needs to be protected with a global lock, because it
// locks multiple IDs at once, and there's no good way to make sure
// the locking happens a deterministic order.
p.graph.imagesMutex.Lock()
defer p.graph.imagesMutex.Unlock()
idMap := make(map[string]struct{})
for _, img := range imgs {
idMap[img.id] = struct{}{}
idMap[img.compatibilityID] = struct{}{}
if p.graph.Exists(img.compatibilityID) {
if _, err := p.graph.GenerateV1CompatibilityChain(img.compatibilityID); err != nil {
logrus.Debugf("Migration v1Compatibility generation error: %v", err)
return
}
}
}
for id := range idMap {
p.graph.imageMutex.Lock(id)
defer p.graph.imageMutex.Unlock(id)
}
// continueReuse controls whether the function will try to find
// existing layers on disk under the old v1 IDs, to avoid repulling
// them. The hashes are checked to ensure these layers are okay to
// use. continueReuse starts out as true, but is set to false if
// the code encounters something that doesn't match the expected hash.
continueReuse := true
for i := len(imgs) - 1; i >= 0; i-- {
if p.graph.Exists(imgs[i].id) {
// Found an image in the graph under the strongID. Validate the
// image before using it.
if err := p.validateImageInGraph(imgs[i].id, imgs, i); err != nil {
continueReuse = false
logrus.Debugf("not using existing strongID: %v", err)
// The strong ID existed in the graph but didn't
// validate successfully. We can't use the strong ID
// because it didn't validate successfully. Treat the
// graph like a hash table with probing... compute
// SHA256(id) until we find an ID that either doesn't
// already exist in the graph, or has existing content
// that validates successfully.
for {
if err := p.tryNextID(imgs, i, idMap); err != nil {
logrus.Debug(err.Error())
} else {
break
}
}
}
continue
}
if continueReuse {
compatibilityID := imgs[i].compatibilityID
if err := p.validateImageInGraph(compatibilityID, imgs, i); err != nil {
logrus.Debugf("stopping ID reuse: %v", err)
continueReuse = false
} else {
// The compatibility ID exists in the graph and was
// validated. Use it.
imgs[i].id = compatibilityID
}
}
}
// fix up the parents of the images
for i := 0; i < len(imgs); i++ {
if i == len(imgs)-1 { // Base layer
imgs[i].parent = ""
} else {
imgs[i].parent = imgs[i+1].id
}
}
}
// validateImageInGraph checks that an image in the graph has the expected
// strongID. id is the entry in the graph to check, imgs is the slice of
// images being processed (for access to the parent), and i is the index
// into this slice which the graph entry should be checked against.
func (p *v2Puller) validateImageInGraph(id string, imgs []contentAddressableDescriptor, i int) error {
img, err := p.graph.Get(id)
if err != nil {
return fmt.Errorf("missing: %v", err)
}
layerID, err := p.graph.getLayerDigest(id)
if err != nil {
return fmt.Errorf("digest: %v", err)
}
var parentID digest.Digest
if i != len(imgs)-1 {
if img.Parent != imgs[i+1].id { // comparing that graph points to validated ID
return fmt.Errorf("parent: %v %v", img.Parent, imgs[i+1].id)
}
parentID = imgs[i+1].strongID
} else if img.Parent != "" {
return fmt.Errorf("unexpected parent: %v", img.Parent)
}
v1Config, err := p.graph.getV1CompatibilityConfig(img.ID)
if err != nil {
return fmt.Errorf("v1Compatibility: %v %v", img.ID, err)
}
json, err := image.MakeImageConfig(v1Config, layerID, parentID)
if err != nil {
return fmt.Errorf("make config: %v", err)
}
if dgst, err := image.StrongID(json); err == nil && dgst == imgs[i].strongID {
logrus.Debugf("Validated %v as %v", dgst, id)
} else {
return fmt.Errorf("digest mismatch: %v %v, error: %v", dgst, imgs[i].strongID, err)
}
// All clear
return nil
}
func (p *v2Puller) tryNextID(imgs []contentAddressableDescriptor, i int, idMap map[string]struct{}) error {
nextID, _ := digest.FromBytes([]byte(imgs[i].id))
imgs[i].id = nextID.Hex()
if _, exists := idMap[imgs[i].id]; !exists {
p.graph.imageMutex.Lock(imgs[i].id)
defer p.graph.imageMutex.Unlock(imgs[i].id)
}
if p.graph.Exists(imgs[i].id) {
if err := p.validateImageInGraph(imgs[i].id, imgs, i); err != nil {
return fmt.Errorf("not using existing strongID permutation %s: %v", imgs[i].id, err)
}
}
return nil
}