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inspect_v2.go
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inspect_v2.go
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package docker
import (
"encoding/json"
"errors"
"fmt"
"runtime"
"github.com/Sirupsen/logrus"
"github.com/docker/distribution"
"github.com/docker/distribution/manifest/manifestlist"
"github.com/docker/distribution/manifest/schema1"
"github.com/docker/distribution/manifest/schema2"
"github.com/docker/distribution/registry/api/errcode"
engineTypes "github.com/docker/docker/api/types"
dockerdistribution "github.com/docker/docker/distribution"
"github.com/docker/docker/image"
"github.com/docker/docker/image/v1"
"github.com/docker/docker/reference"
"github.com/docker/docker/registry"
"github.com/estesp/manifest-tool/types"
"github.com/opencontainers/go-digest"
"golang.org/x/net/context"
)
type v2ManifestFetcher struct {
endpoint registry.APIEndpoint
repoInfo *registry.RepositoryInfo
repo distribution.Repository
confirmedV2 bool
authConfig engineTypes.AuthConfig
service registry.Service
}
type manifestInfo struct {
blobDigests []digest.Digest
layers []string
digest digest.Digest
platform manifestlist.PlatformSpec
length int64
jsonBytes []byte
}
func (mf *v2ManifestFetcher) Fetch(ctx context.Context, ref reference.Named) ([]types.ImageInspect, error) {
var err error
mf.repo, mf.confirmedV2, err = dockerdistribution.NewV2Repository(ctx, mf.repoInfo, mf.endpoint, nil, &mf.authConfig, "pull")
if err != nil {
logrus.Debugf("Error getting v2 registry: %v", err)
return nil, err
}
images, err := mf.fetchWithRepository(ctx, ref)
if err != nil {
if _, ok := err.(fallbackError); ok {
return nil, err
}
if continueOnError(err) {
logrus.Errorf("Error trying v2 registry: %v", err)
return nil, fallbackError{err: err, confirmedV2: mf.confirmedV2, transportOK: true}
}
}
for _, img := range images {
img.MediaType = schema2.MediaTypeManifest
}
return images, err
}
func (mf *v2ManifestFetcher) fetchWithRepository(ctx context.Context, ref reference.Named) ([]types.ImageInspect, error) {
var (
manifest distribution.Manifest
tagOrDigest string // Used for logging/progress only
tagList = []string{}
imageList = []types.ImageInspect{}
)
manSvc, err := mf.repo.Manifests(ctx)
if err != nil {
return nil, err
}
if _, isTagged := ref.(reference.NamedTagged); !isTagged {
ref, err = reference.WithTag(ref, reference.DefaultTag)
if err != nil {
return nil, err
}
}
if tagged, isTagged := ref.(reference.NamedTagged); isTagged {
// NOTE: not using TagService.Get, since it uses HEAD requests
// against the manifests endpoint, which are not supported by
// all registry versions.
manifest, err = manSvc.Get(ctx, "", distribution.WithTag(tagged.Tag()))
if err != nil {
return nil, allowV1Fallback(err)
}
tagOrDigest = tagged.Tag()
} else if digested, isDigested := ref.(reference.Canonical); isDigested {
manifest, err = manSvc.Get(ctx, digested.Digest())
if err != nil {
return nil, err
}
tagOrDigest = digested.Digest().String()
} else {
return nil, fmt.Errorf("internal error: reference has neither a tag nor a digest: %s", ref.String())
}
if manifest == nil {
return nil, fmt.Errorf("image manifest does not exist for tag or digest %q", tagOrDigest)
}
// If manSvc.Get succeeded, we can be confident that the registry on
// the other side speaks the v2 protocol.
mf.confirmedV2 = true
tagList, err = mf.repo.Tags(ctx).All(ctx)
if err != nil {
// If this repository doesn't exist on V2, we should
// permit a fallback to V1.
return nil, allowV1Fallback(err)
}
var (
images []*image.Image
mfInfos []manifestInfo
mediaType []string
)
switch v := manifest.(type) {
case *schema1.SignedManifest:
image, mfInfo, err := mf.pullSchema1(ctx, ref, v)
images = append(images, image)
mfInfos = append(mfInfos, mfInfo)
mediaType = append(mediaType, schema1.MediaTypeManifest)
if err != nil {
return nil, err
}
case *schema2.DeserializedManifest:
image, mfInfo, err := mf.pullSchema2(ctx, ref, v)
images = append(images, image)
mfInfos = append(mfInfos, mfInfo)
mediaType = append(mediaType, schema2.MediaTypeManifest)
if err != nil {
return nil, err
}
case *manifestlist.DeserializedManifestList:
images, mfInfos, mediaType, err = mf.pullManifestList(ctx, ref, v)
if err != nil {
return nil, err
}
default:
return nil, errors.New("unsupported manifest format")
}
for idx, img := range images {
imgReturn := makeImageInspect(img, tagOrDigest, mfInfos[idx], mediaType[idx], tagList)
imageList = append(imageList, *imgReturn)
}
return imageList, nil
}
func (mf *v2ManifestFetcher) pullSchema1(ctx context.Context, ref reference.Named, unverifiedManifest *schema1.SignedManifest) (img *image.Image, mfInfo manifestInfo, err error) {
mfInfo = manifestInfo{}
var verifiedManifest *schema1.Manifest
verifiedManifest, err = verifySchema1Manifest(unverifiedManifest, ref)
if err != nil {
return nil, mfInfo, err
}
// remove duplicate layers and check parent chain validity
err = fixManifestLayers(verifiedManifest)
if err != nil {
return nil, mfInfo, err
}
// Image history converted to the new format
var history []image.History
// Note that the order of this loop is in the direction of bottom-most
// to top-most, so that the downloads slice gets ordered correctly.
for i := len(verifiedManifest.FSLayers) - 1; i >= 0; i-- {
var throwAway struct {
ThrowAway bool `json:"throwaway,omitempty"`
}
if err := json.Unmarshal([]byte(verifiedManifest.History[i].V1Compatibility), &throwAway); err != nil {
return nil, mfInfo, err
}
h, err := v1.HistoryFromConfig([]byte(verifiedManifest.History[i].V1Compatibility), throwAway.ThrowAway)
if err != nil {
return nil, mfInfo, err
}
history = append(history, h)
mfInfo.blobDigests = append(mfInfo.blobDigests, verifiedManifest.FSLayers[i].BlobSum)
}
rootFS := image.NewRootFS()
configRaw, err := makeRawConfigFromV1Config([]byte(verifiedManifest.History[0].V1Compatibility), rootFS, history)
config, err := json.Marshal(configRaw)
if err != nil {
return nil, mfInfo, err
}
img, err = image.NewFromJSON(config)
if err != nil {
return nil, mfInfo, err
}
mfInfo.digest = digest.FromBytes(unverifiedManifest.Canonical)
// add the size of the manifest to the info struct; needed for assembling proper
// manifest lists
mfInfo.length = int64(len(unverifiedManifest.Canonical))
mfInfo.jsonBytes, err = unverifiedManifest.MarshalJSON()
if err != nil {
return nil, mfInfo, err
}
return img, mfInfo, nil
}
func verifySchema1Manifest(signedManifest *schema1.SignedManifest, ref reference.Named) (m *schema1.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 digested, isCanonical := ref.(reference.Canonical); isCanonical {
verifier := digested.Digest().Verifier()
if _, err := verifier.Write(signedManifest.Canonical); err != nil {
return nil, err
}
if !verifier.Verified() {
err := fmt.Errorf("image verification failed for digest %s", digested.Digest())
logrus.Error(err)
return nil, err
}
}
m = &signedManifest.Manifest
if m.SchemaVersion != 1 {
return nil, fmt.Errorf("unsupported schema version %d for %q", m.SchemaVersion, ref.String())
}
if len(m.FSLayers) != len(m.History) {
return nil, fmt.Errorf("length of history not equal to number of layers for %q", ref.String())
}
if len(m.FSLayers) == 0 {
return nil, fmt.Errorf("no FSLayers in manifest for %q", ref.String())
}
return m, nil
}
func fixManifestLayers(m *schema1.Manifest) error {
imgs := make([]*image.V1Image, len(m.FSLayers))
for i := range m.FSLayers {
img := &image.V1Image{}
if err := json.Unmarshal([]byte(m.History[i].V1Compatibility), img); err != nil {
return err
}
imgs[i] = img
if err := v1.ValidateID(img.ID); err != nil {
return err
}
}
if imgs[len(imgs)-1].Parent != "" && runtime.GOOS != "windows" {
// Windows base layer can point to a base layer parent that is not in manifest.
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 imgs {
// 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(imgs) - 2; i >= 0; i-- {
if imgs[i].ID == imgs[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 imgs[i].Parent != imgs[i+1].ID {
return fmt.Errorf("Invalid parent ID. Expected %v, got %v.", imgs[i+1].ID, imgs[i].Parent)
}
}
return nil
}
func (mf *v2ManifestFetcher) pullSchema2(ctx context.Context, ref reference.Named, mfst *schema2.DeserializedManifest) (img *image.Image, mfInfo manifestInfo, err error) {
mfInfo.digest, err = schema2ManifestDigest(ref, mfst)
if err != nil {
return nil, mfInfo, err
}
target := mfst.Target()
configChan := make(chan []byte, 1)
errChan := make(chan error, 1)
var cancel func()
ctx, cancel = context.WithCancel(ctx)
// Pull the image config
go func() {
configJSON, err := mf.pullSchema2ImageConfig(ctx, target.Digest)
if err != nil {
errChan <- ImageConfigPullError{Err: err}
cancel()
return
}
configChan <- configJSON
}()
var (
configJSON []byte // raw serialized image config
unmarshalledConfig image.Image // deserialized image config
)
if runtime.GOOS == "windows" {
configJSON, unmarshalledConfig, err = receiveConfig(configChan, errChan)
if err != nil {
return nil, mfInfo, err
}
if unmarshalledConfig.RootFS == nil {
return nil, mfInfo, errors.New("image config has no rootfs section")
}
}
if configJSON == nil {
configJSON, unmarshalledConfig, err = receiveConfig(configChan, errChan)
if err != nil {
return nil, mfInfo, err
}
}
// collect all references so that we can ask for cross-repo blob
// mount in the cases where a manifest list is created from images
// outside the target repo
for _, descriptor := range mfst.References() {
mfInfo.blobDigests = append(mfInfo.blobDigests, descriptor.Digest)
}
for _, descriptor := range mfst.Layers {
mfInfo.layers = append(mfInfo.layers, descriptor.Digest.String())
}
img, err = image.NewFromJSON(configJSON)
if err != nil {
return nil, mfInfo, err
}
// add the size of the manifest to the image response; needed for assembling proper
// manifest lists
_, mfBytes, err := mfst.Payload()
if err != nil {
return nil, mfInfo, err
}
mfInfo.length = int64(len(mfBytes))
mfInfo.jsonBytes = mfBytes
return img, mfInfo, nil
}
func (mf *v2ManifestFetcher) pullSchema2ImageConfig(ctx context.Context, dgst digest.Digest) (configJSON []byte, err error) {
blobs := mf.repo.Blobs(ctx)
configJSON, err = blobs.Get(ctx, dgst)
if err != nil {
return nil, err
}
// Verify image config digest
verifier := dgst.Verifier()
if _, err := verifier.Write(configJSON); err != nil {
return nil, err
}
if !verifier.Verified() {
err := fmt.Errorf("image config verification failed for digest %s", dgst)
logrus.Error(err)
return nil, err
}
return configJSON, nil
}
func receiveConfig(configChan <-chan []byte, errChan <-chan error) ([]byte, image.Image, error) {
select {
case configJSON := <-configChan:
var unmarshalledConfig image.Image
if err := json.Unmarshal(configJSON, &unmarshalledConfig); err != nil {
return nil, image.Image{}, err
}
return configJSON, unmarshalledConfig, nil
case err := <-errChan:
return nil, image.Image{}, err
// Don't need a case for ctx.Done in the select because cancellation
// will trigger an error in p.pullSchema2ImageConfig.
}
}
// ImageConfigPullError is an error pulling the image config blob
// (only applies to schema2).
type ImageConfigPullError struct {
Err error
}
// Error returns the error string for ImageConfigPullError.
func (e ImageConfigPullError) Error() string {
return "error pulling image configuration: " + e.Err.Error()
}
// allowV1Fallback checks if the error is a possible reason to fallback to v1
// (even if confirmedV2 has been set already), and if so, wraps the error in
// a fallbackError with confirmedV2 set to false. Otherwise, it returns the
// error unmodified.
func allowV1Fallback(err error) error {
switch v := err.(type) {
case errcode.Errors:
if len(v) != 0 {
if v0, ok := v[0].(errcode.Error); ok && shouldV2Fallback(v0) {
return fallbackError{err: err, confirmedV2: false, transportOK: true}
}
}
case errcode.Error:
if shouldV2Fallback(v) {
return fallbackError{err: err, confirmedV2: false, transportOK: true}
}
}
return err
}
// schema2ManifestDigest computes the manifest digest, and, if pulling by
// digest, ensures that it matches the requested digest.
func schema2ManifestDigest(ref reference.Named, mfst distribution.Manifest) (digest.Digest, error) {
_, canonical, err := mfst.Payload()
if err != nil {
return "", err
}
// If pull by digest, then verify the manifest digest.
if digested, isDigested := ref.(reference.Canonical); isDigested {
verifier := digested.Digest().Verifier()
if _, err := verifier.Write(canonical); err != nil {
return "", err
}
if !verifier.Verified() {
err := fmt.Errorf("manifest verification failed for digest %s", digested.Digest())
logrus.Error(err)
return "", err
}
return digested.Digest(), nil
}
return digest.FromBytes(canonical), nil
}
// pullManifestList handles "manifest lists" which point to various
// platform-specific manifests.
func (mf *v2ManifestFetcher) pullManifestList(ctx context.Context, ref reference.Named, mfstList *manifestlist.DeserializedManifestList) ([]*image.Image, []manifestInfo, []string, error) {
var (
imageList = []*image.Image{}
mfInfos = []manifestInfo{}
mediaType = []string{}
)
manifestListDigest, err := schema2ManifestDigest(ref, mfstList)
if err != nil {
return nil, nil, nil, err
}
logrus.Debugf("Pulling manifest list entries for ML digest %v", manifestListDigest)
// for displaying basic information on the "outer" manifest list entry, we will
// create the first entry in the returned arrays to hold the manifest list details:
mfInfos = append(mfInfos, manifestInfo{digest: manifestListDigest})
mediaType = append(mediaType, mfstList.MediaType)
imageList = append(imageList, &image.Image{})
for _, manifestDescriptor := range mfstList.Manifests {
manSvc, err := mf.repo.Manifests(ctx)
if err != nil {
return nil, nil, nil, err
}
thisDigest := manifestDescriptor.Digest
thisPlatform := manifestDescriptor.Platform
manifest, err := manSvc.Get(ctx, thisDigest)
if err != nil {
return nil, nil, nil, err
}
manifestRef, err := reference.WithDigest(ref, thisDigest)
if err != nil {
return nil, nil, nil, err
}
switch v := manifest.(type) {
case *schema1.SignedManifest:
img, mfInfo, err := mf.pullSchema1(ctx, manifestRef, v)
imageList = append(imageList, img)
mfInfo.platform = thisPlatform
mfInfos = append(mfInfos, mfInfo)
mediaType = append(mediaType, schema1.MediaTypeManifest)
if err != nil {
return nil, nil, nil, err
}
case *schema2.DeserializedManifest:
img, mfInfo, err := mf.pullSchema2(ctx, manifestRef, v)
imageList = append(imageList, img)
mfInfo.platform = thisPlatform
mfInfos = append(mfInfos, mfInfo)
mediaType = append(mediaType, schema2.MediaTypeManifest)
if err != nil {
return nil, nil, nil, err
}
default:
return nil, nil, nil, errors.New("unsupported manifest format")
}
}
return imageList, mfInfos, mediaType, err
}