/
docker_image_src.go
451 lines (410 loc) · 15.4 KB
/
docker_image_src.go
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package docker
import (
"context"
"fmt"
"io"
"io/ioutil"
"mime"
"net/http"
"net/url"
"os"
"strconv"
"github.com/containers/image/v4/docker/reference"
"github.com/containers/image/v4/manifest"
"github.com/containers/image/v4/pkg/sysregistriesv2"
"github.com/containers/image/v4/types"
"github.com/docker/distribution/registry/client"
digest "github.com/opencontainers/go-digest"
"github.com/pkg/errors"
"github.com/sirupsen/logrus"
)
type dockerImageSource struct {
ref dockerReference
c *dockerClient
// State
cachedManifest []byte // nil if not loaded yet
cachedManifestMIMEType string // Only valid if cachedManifest != nil
}
// newImageSource creates a new ImageSource for the specified image reference.
// The caller must call .Close() on the returned ImageSource.
func newImageSource(ctx context.Context, sys *types.SystemContext, ref dockerReference) (*dockerImageSource, error) {
registry, err := sysregistriesv2.FindRegistry(sys, ref.ref.Name())
if err != nil {
return nil, errors.Wrapf(err, "error loading registries configuration")
}
if registry == nil {
// No configuration was found for the provided reference, so use the
// equivalent of a default configuration.
registry = &sysregistriesv2.Registry{
Endpoint: sysregistriesv2.Endpoint{
Location: ref.ref.String(),
},
Prefix: ref.ref.String(),
}
}
primaryDomain := reference.Domain(ref.ref)
// Check all endpoints for the manifest availability. If we find one that does
// contain the image, it will be used for all future pull actions. Always try the
// non-mirror original location last; this both transparently handles the case
// of no mirrors configured, and ensures we return the error encountered when
// acessing the upstream location if all endpoints fail.
manifestLoadErr := errors.New("Internal error: newImageSource returned without trying any endpoint")
pullSources, err := registry.PullSourcesFromReference(ref.ref)
if err != nil {
return nil, err
}
for _, pullSource := range pullSources {
logrus.Debugf("Trying to pull %q", pullSource.Reference)
dockerRef, err := newReference(pullSource.Reference)
if err != nil {
return nil, err
}
endpointSys := sys
// sys.DockerAuthConfig does not explicitly specify a registry; we must not blindly send the credentials intended for the primary endpoint to mirrors.
if endpointSys != nil && endpointSys.DockerAuthConfig != nil && reference.Domain(dockerRef.ref) != primaryDomain {
copy := *endpointSys
copy.DockerAuthConfig = nil
endpointSys = ©
}
client, err := newDockerClientFromRef(endpointSys, dockerRef, false, "pull")
if err != nil {
return nil, err
}
client.tlsClientConfig.InsecureSkipVerify = pullSource.Endpoint.Insecure
testImageSource := &dockerImageSource{
ref: dockerRef,
c: client,
}
manifestLoadErr = testImageSource.ensureManifestIsLoaded(ctx)
if manifestLoadErr == nil {
return testImageSource, nil
}
}
return nil, manifestLoadErr
}
// Reference returns the reference used to set up this source, _as specified by the user_
// (not as the image itself, or its underlying storage, claims). This can be used e.g. to determine which public keys are trusted for this image.
func (s *dockerImageSource) Reference() types.ImageReference {
return s.ref
}
// Close removes resources associated with an initialized ImageSource, if any.
func (s *dockerImageSource) Close() error {
return nil
}
// LayerInfosForCopy() returns updated layer info that should be used when reading, in preference to values in the manifest, if specified.
func (s *dockerImageSource) LayerInfosForCopy(ctx context.Context) ([]types.BlobInfo, error) {
return nil, nil
}
// simplifyContentType drops parameters from a HTTP media type (see https://tools.ietf.org/html/rfc7231#section-3.1.1.1)
// Alternatively, an empty string is returned unchanged, and invalid values are "simplified" to an empty string.
func simplifyContentType(contentType string) string {
if contentType == "" {
return contentType
}
mimeType, _, err := mime.ParseMediaType(contentType)
if err != nil {
return ""
}
return mimeType
}
// GetManifest returns the image's manifest along with its MIME type (which may be empty when it can't be determined but the manifest is available).
// It may use a remote (= slow) service.
// If instanceDigest is not nil, it contains a digest of the specific manifest instance to retrieve (when the primary manifest is a manifest list);
// this never happens if the primary manifest is not a manifest list (e.g. if the source never returns manifest lists).
func (s *dockerImageSource) GetManifest(ctx context.Context, instanceDigest *digest.Digest) ([]byte, string, error) {
if instanceDigest != nil {
return s.fetchManifest(ctx, instanceDigest.String())
}
err := s.ensureManifestIsLoaded(ctx)
if err != nil {
return nil, "", err
}
return s.cachedManifest, s.cachedManifestMIMEType, nil
}
func (s *dockerImageSource) fetchManifest(ctx context.Context, tagOrDigest string) ([]byte, string, error) {
path := fmt.Sprintf(manifestPath, reference.Path(s.ref.ref), tagOrDigest)
headers := map[string][]string{
"Accept": manifest.DefaultRequestedManifestMIMETypes,
}
res, err := s.c.makeRequest(ctx, "GET", path, headers, nil, v2Auth, nil)
if err != nil {
return nil, "", err
}
defer res.Body.Close()
if res.StatusCode != http.StatusOK {
return nil, "", errors.Wrapf(client.HandleErrorResponse(res), "Error reading manifest %s in %s", tagOrDigest, s.ref.ref.Name())
}
manblob, err := ioutil.ReadAll(res.Body)
if err != nil {
return nil, "", err
}
return manblob, simplifyContentType(res.Header.Get("Content-Type")), nil
}
// ensureManifestIsLoaded sets s.cachedManifest and s.cachedManifestMIMEType
//
// ImageSource implementations are not required or expected to do any caching,
// but because our signatures are “attached” to the manifest digest,
// we need to ensure that the digest of the manifest returned by GetManifest(ctx, nil)
// and used by GetSignatures(ctx, nil) are consistent, otherwise we would get spurious
// signature verification failures when pulling while a tag is being updated.
func (s *dockerImageSource) ensureManifestIsLoaded(ctx context.Context) error {
if s.cachedManifest != nil {
return nil
}
reference, err := s.ref.tagOrDigest()
if err != nil {
return err
}
manblob, mt, err := s.fetchManifest(ctx, reference)
if err != nil {
return err
}
// We might validate manblob against the Docker-Content-Digest header here to protect against transport errors.
s.cachedManifest = manblob
s.cachedManifestMIMEType = mt
return nil
}
func (s *dockerImageSource) getExternalBlob(ctx context.Context, urls []string) (io.ReadCloser, int64, error) {
var (
resp *http.Response
err error
)
for _, url := range urls {
resp, err = s.c.makeRequestToResolvedURL(ctx, "GET", url, nil, nil, -1, noAuth, nil)
if err == nil {
if resp.StatusCode != http.StatusOK {
err = errors.Errorf("error fetching external blob from %q: %d (%s)", url, resp.StatusCode, http.StatusText(resp.StatusCode))
logrus.Debug(err)
continue
}
break
}
}
if err != nil {
return nil, 0, err
}
return resp.Body, getBlobSize(resp), nil
}
func getBlobSize(resp *http.Response) int64 {
size, err := strconv.ParseInt(resp.Header.Get("Content-Length"), 10, 64)
if err != nil {
size = -1
}
return size
}
// HasThreadSafeGetBlob indicates whether GetBlob can be executed concurrently.
func (s *dockerImageSource) HasThreadSafeGetBlob() bool {
return true
}
// GetBlob returns a stream for the specified blob, and the blob’s size (or -1 if unknown).
// The Digest field in BlobInfo is guaranteed to be provided, Size may be -1 and MediaType may be optionally provided.
// May update BlobInfoCache, preferably after it knows for certain that a blob truly exists at a specific location.
func (s *dockerImageSource) GetBlob(ctx context.Context, info types.BlobInfo, cache types.BlobInfoCache) (io.ReadCloser, int64, error) {
if len(info.URLs) != 0 {
return s.getExternalBlob(ctx, info.URLs)
}
path := fmt.Sprintf(blobsPath, reference.Path(s.ref.ref), info.Digest.String())
logrus.Debugf("Downloading %s", path)
res, err := s.c.makeRequest(ctx, "GET", path, nil, nil, v2Auth, nil)
if err != nil {
return nil, 0, err
}
if res.StatusCode != http.StatusOK {
// print url also
return nil, 0, errors.Errorf("Invalid status code returned when fetching blob %d (%s)", res.StatusCode, http.StatusText(res.StatusCode))
}
cache.RecordKnownLocation(s.ref.Transport(), bicTransportScope(s.ref), info.Digest, newBICLocationReference(s.ref))
return res.Body, getBlobSize(res), nil
}
// GetSignatures returns the image's signatures. It may use a remote (= slow) service.
// If instanceDigest is not nil, it contains a digest of the specific manifest instance to retrieve signatures for
// (when the primary manifest is a manifest list); this never happens if the primary manifest is not a manifest list
// (e.g. if the source never returns manifest lists).
func (s *dockerImageSource) GetSignatures(ctx context.Context, instanceDigest *digest.Digest) ([][]byte, error) {
if err := s.c.detectProperties(ctx); err != nil {
return nil, err
}
switch {
case s.c.signatureBase != nil:
return s.getSignaturesFromLookaside(ctx, instanceDigest)
case s.c.supportsSignatures:
return s.getSignaturesFromAPIExtension(ctx, instanceDigest)
default:
return [][]byte{}, nil
}
}
// manifestDigest returns a digest of the manifest, from instanceDigest if non-nil; or from the supplied reference,
// or finally, from a fetched manifest.
func (s *dockerImageSource) manifestDigest(ctx context.Context, instanceDigest *digest.Digest) (digest.Digest, error) {
if instanceDigest != nil {
return *instanceDigest, nil
}
if digested, ok := s.ref.ref.(reference.Digested); ok {
d := digested.Digest()
if d.Algorithm() == digest.Canonical {
return d, nil
}
}
if err := s.ensureManifestIsLoaded(ctx); err != nil {
return "", err
}
return manifest.Digest(s.cachedManifest)
}
// getSignaturesFromLookaside implements GetSignatures() from the lookaside location configured in s.c.signatureBase,
// which is not nil.
func (s *dockerImageSource) getSignaturesFromLookaside(ctx context.Context, instanceDigest *digest.Digest) ([][]byte, error) {
manifestDigest, err := s.manifestDigest(ctx, instanceDigest)
if err != nil {
return nil, err
}
// NOTE: Keep this in sync with docs/signature-protocols.md!
signatures := [][]byte{}
for i := 0; ; i++ {
url := signatureStorageURL(s.c.signatureBase, manifestDigest, i)
if url == nil {
return nil, errors.Errorf("Internal error: signatureStorageURL with non-nil base returned nil")
}
signature, missing, err := s.getOneSignature(ctx, url)
if err != nil {
return nil, err
}
if missing {
break
}
signatures = append(signatures, signature)
}
return signatures, nil
}
// getOneSignature downloads one signature from url.
// If it successfully determines that the signature does not exist, returns with missing set to true and error set to nil.
// NOTE: Keep this in sync with docs/signature-protocols.md!
func (s *dockerImageSource) getOneSignature(ctx context.Context, url *url.URL) (signature []byte, missing bool, err error) {
switch url.Scheme {
case "file":
logrus.Debugf("Reading %s", url.Path)
sig, err := ioutil.ReadFile(url.Path)
if err != nil {
if os.IsNotExist(err) {
return nil, true, nil
}
return nil, false, err
}
return sig, false, nil
case "http", "https":
logrus.Debugf("GET %s", url)
req, err := http.NewRequest("GET", url.String(), nil)
if err != nil {
return nil, false, err
}
req = req.WithContext(ctx)
res, err := s.c.client.Do(req)
if err != nil {
return nil, false, err
}
defer res.Body.Close()
if res.StatusCode == http.StatusNotFound {
return nil, true, nil
} else if res.StatusCode != http.StatusOK {
return nil, false, errors.Errorf("Error reading signature from %s: status %d (%s)", url.String(), res.StatusCode, http.StatusText(res.StatusCode))
}
sig, err := ioutil.ReadAll(res.Body)
if err != nil {
return nil, false, err
}
return sig, false, nil
default:
return nil, false, errors.Errorf("Unsupported scheme when reading signature from %s", url.String())
}
}
// getSignaturesFromAPIExtension implements GetSignatures() using the X-Registry-Supports-Signatures API extension.
func (s *dockerImageSource) getSignaturesFromAPIExtension(ctx context.Context, instanceDigest *digest.Digest) ([][]byte, error) {
manifestDigest, err := s.manifestDigest(ctx, instanceDigest)
if err != nil {
return nil, err
}
parsedBody, err := s.c.getExtensionsSignatures(ctx, s.ref, manifestDigest)
if err != nil {
return nil, err
}
var sigs [][]byte
for _, sig := range parsedBody.Signatures {
if sig.Version == extensionSignatureSchemaVersion && sig.Type == extensionSignatureTypeAtomic {
sigs = append(sigs, sig.Content)
}
}
return sigs, nil
}
// deleteImage deletes the named image from the registry, if supported.
func deleteImage(ctx context.Context, sys *types.SystemContext, ref dockerReference) error {
// docker/distribution does not document what action should be used for deleting images.
//
// Current docker/distribution requires "pull" for reading the manifest and "delete" for deleting it.
// quay.io requires "push" (an explicit "pull" is unnecessary), does not grant any token (fails parsing the request) if "delete" is included.
// OpenShift ignores the action string (both the password and the token is an OpenShift API token identifying a user).
//
// We have to hard-code a single string, luckily both docker/distribution and quay.io support "*" to mean "everything".
c, err := newDockerClientFromRef(sys, ref, true, "*")
if err != nil {
return err
}
headers := map[string][]string{
"Accept": manifest.DefaultRequestedManifestMIMETypes,
}
refTail, err := ref.tagOrDigest()
if err != nil {
return err
}
getPath := fmt.Sprintf(manifestPath, reference.Path(ref.ref), refTail)
get, err := c.makeRequest(ctx, "GET", getPath, headers, nil, v2Auth, nil)
if err != nil {
return err
}
defer get.Body.Close()
manifestBody, err := ioutil.ReadAll(get.Body)
if err != nil {
return err
}
switch get.StatusCode {
case http.StatusOK:
case http.StatusNotFound:
return errors.Errorf("Unable to delete %v. Image may not exist or is not stored with a v2 Schema in a v2 registry", ref.ref)
default:
return errors.Errorf("Failed to delete %v: %s (%v)", ref.ref, manifestBody, get.Status)
}
digest := get.Header.Get("Docker-Content-Digest")
deletePath := fmt.Sprintf(manifestPath, reference.Path(ref.ref), digest)
// When retrieving the digest from a registry >= 2.3 use the following header:
// "Accept": "application/vnd.docker.distribution.manifest.v2+json"
delete, err := c.makeRequest(ctx, "DELETE", deletePath, headers, nil, v2Auth, nil)
if err != nil {
return err
}
defer delete.Body.Close()
body, err := ioutil.ReadAll(delete.Body)
if err != nil {
return err
}
if delete.StatusCode != http.StatusAccepted {
return errors.Errorf("Failed to delete %v: %s (%v)", deletePath, string(body), delete.Status)
}
if c.signatureBase != nil {
manifestDigest, err := manifest.Digest(manifestBody)
if err != nil {
return err
}
for i := 0; ; i++ {
url := signatureStorageURL(c.signatureBase, manifestDigest, i)
if url == nil {
return errors.Errorf("Internal error: signatureStorageURL with non-nil base returned nil")
}
missing, err := c.deleteOneSignature(url)
if err != nil {
return err
}
if missing {
break
}
}
}
return nil
}