Add oci-archive transport that creates a tar archive of an image

Signed-off-by: umohnani8 <umohnani@redhat.com>

oci/archive/oci_dest.go

@@ -0,0 +1,135 @@
+package archive
+
+import (
+	"io"
+	"os"
+
+	"github.com/containers/image/types"
+	"github.com/containers/storage/pkg/archive"
+	"github.com/pkg/errors"
+)
+
+type ociArchiveImageDestination struct {
+	ref          ociArchiveReference
+	unpackedDest types.ImageDestination
+	tempDirRef   tempDirOCIRef
+}
+
+// newImageDestination returns an ImageDestination for writing to an existing directory.
+func newImageDestination(ctx *types.SystemContext, ref ociArchiveReference) (types.ImageDestination, error) {
+	tempDirRef, err := createOCIRef(ref.image)
+	if err != nil {
+		return nil, errors.Wrapf(err, "error creating oci reference")
+	}
+	unpackedDest, err := tempDirRef.ociRefExtracted.NewImageDestination(ctx)
+	if err != nil {
+		if err := tempDirRef.deleteTempDir(); err != nil {
+			return nil, errors.Wrapf(err, "error deleting temp directory", tempDirRef.tempDirectory)
+		}
+		return nil, err
+	}
+	return &ociArchiveImageDestination{ref: ref,
+		unpackedDest: unpackedDest,
+		tempDirRef:   tempDirRef}, nil
+}
+
+// Reference returns the reference used to set up this destination.
+func (d *ociArchiveImageDestination) Reference() types.ImageReference {
+	return d.ref
+}
+
+// Close removes resources associated with an initialized ImageDestination, if any
+// Close deletes the temp directory of the oci-archive image
+func (d *ociArchiveImageDestination) Close() error {
+	defer d.tempDirRef.deleteTempDir()
+	return d.unpackedDest.Close()
+}
+
+func (d *ociArchiveImageDestination) SupportedManifestMIMETypes() []string {
+	return d.unpackedDest.SupportedManifestMIMETypes()
+}
+
+// SupportsSignatures returns an error (to be displayed to the user) if the destination certainly can't store signatures
+func (d *ociArchiveImageDestination) SupportsSignatures() error {
+	return d.unpackedDest.SupportsSignatures()
+}
+
+// ShouldCompressLayers returns true iff it is desirable to compress layer blobs written to this destination
+func (d *ociArchiveImageDestination) ShouldCompressLayers() bool {
+	return d.unpackedDest.ShouldCompressLayers()
+}
+
+// AcceptsForeignLayerURLs returns false iff foreign layers in manifest should be actually
+// uploaded to the image destination, true otherwise.
+func (d *ociArchiveImageDestination) AcceptsForeignLayerURLs() bool {
+	return d.unpackedDest.AcceptsForeignLayerURLs()
+}
+
+// MustMatchRuntimeOS returns true iff the destination can store only images targeted for the current runtime OS. False otherwise
+func (d *ociArchiveImageDestination) MustMatchRuntimeOS() bool {
+	return d.unpackedDest.MustMatchRuntimeOS()
+}
+
+// PutBlob writes contents of stream and returns data representing the result (with all data filled in).
+// inputInfo.Digest can be optionally provided if known; it is not mandatory for the implementation to verify it.
+// inputInfo.Size is the expected length of stream, if known.
+func (d *ociArchiveImageDestination) PutBlob(stream io.Reader, inputInfo types.BlobInfo) (types.BlobInfo, error) {
+	return d.unpackedDest.PutBlob(stream, inputInfo)
+}
+
+// HasBlob returns true iff the image destination already contains a blob with the matching digest which can be reapplied using ReapplyBlob
+func (d *ociArchiveImageDestination) HasBlob(info types.BlobInfo) (bool, int64, error) {
+	return d.unpackedDest.HasBlob(info)
+}
+
+func (d *ociArchiveImageDestination) ReapplyBlob(info types.BlobInfo) (types.BlobInfo, error) {
+	return d.unpackedDest.ReapplyBlob(info)
+}
+
+// PutManifest writes manifest to the destination
+func (d *ociArchiveImageDestination) PutManifest(m []byte) error {
+	return d.unpackedDest.PutManifest(m)
+}
+
+func (d *ociArchiveImageDestination) PutSignatures(signatures [][]byte) error {
+	return d.unpackedDest.PutSignatures(signatures)
+}
+
+// Commit marks the process of storing the image as successful and asks for the image to be persisted
+// after the directory is made, it is tarred up into a file and the directory is deleted
+func (d *ociArchiveImageDestination) Commit() error {
+	if err := d.unpackedDest.Commit(); err != nil {
+		return errors.Wrapf(err, "error storing image %q", d.ref.image)
+	}
+
+	// path of directory to tar up
+	src := d.tempDirRef.tempDirectory
+	// path to save tarred up file
+	dst := d.ref.resolvedFile
+	if err := tarDirectory(src, dst); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// tar converts the directory at src and saves it to dst
+func tarDirectory(src, dst string) error {
+	// input is a stream of bytes from the archive of the directory at path
+	input, err := archive.Tar(src, archive.Uncompressed)
+	if err != nil {
+		return errors.Wrapf(err, "error retrieving stream of bytes from %q", src)
+	}
+
+	// creates the tar file
+	outFile, err := os.Create(dst)
+	if err != nil {
+		return errors.Wrapf(err, "error creating tar file %q", dst)
+	}
+	defer outFile.Close()
+
+	// copies the contents of the directory to the tar file
+	_, err = io.Copy(outFile, input)
+
+	return err
+}

oci/archive/oci_src.go

@@ -0,0 +1,88 @@
+package archive
+
+import (
+	"context"
+	"io"
+
+	ocilayout "github.com/containers/image/oci/layout"
+	"github.com/containers/image/types"
+	digest "github.com/opencontainers/go-digest"
+	imgspecv1 "github.com/opencontainers/image-spec/specs-go/v1"
+	"github.com/pkg/errors"
+)
+
+type ociArchiveImageSource struct {
+	ref         ociArchiveReference
+	unpackedSrc types.ImageSource
+	tempDirRef  tempDirOCIRef
+}
+
+// newImageSource returns an ImageSource for reading from an existing directory.
+// newImageSource untars the file and saves it in a temp directory
+func newImageSource(ctx *types.SystemContext, ref ociArchiveReference, requestedManifestMIMETypes []string) (types.ImageSource, error) {
+	tempDirRef, err := createUntarTempDir(ref)
+	if err != nil {
+		return nil, errors.Wrap(err, "error creating temp directory")
+	}
+
+	unpackedSrc, err := tempDirRef.ociRefExtracted.NewImageSource(ctx, requestedManifestMIMETypes)
+	if err != nil {
+		if err := tempDirRef.deleteTempDir(); err != nil {
+			return nil, errors.Wrapf(err, "error deleting temp directory", tempDirRef.tempDirectory)
+		}
+		return nil, err
+	}
+	return &ociArchiveImageSource{ref: ref,
+		unpackedSrc: unpackedSrc,
+		tempDirRef:  tempDirRef}, nil
+}
+
+// LoadManifestDescriptor loads the manifest
+func LoadManifestDescriptor(imgRef types.ImageReference) (imgspecv1.Descriptor, error) {
+	ociArchRef, ok := imgRef.(ociArchiveReference)
+	if !ok {
+		return imgspecv1.Descriptor{}, errors.Errorf("error typecasting, need type ociArchiveReference")
+	}
+	tempDirRef, err := createUntarTempDir(ociArchRef)
+	if err != nil {
+		return imgspecv1.Descriptor{}, errors.Wrap(err, "error creating temp directory")
+	}
+	defer tempDirRef.deleteTempDir()
+
+	descriptor, err := ocilayout.LoadManifestDescriptor(tempDirRef.ociRefExtracted)
+	if err != nil {
+		return imgspecv1.Descriptor{}, errors.Wrap(err, "error loading index")
+	}
+	return descriptor, nil
+}
+
+// Reference returns the reference used to set up this source.
+func (s *ociArchiveImageSource) Reference() types.ImageReference {
+	return s.ref
+}
+
+// Close removes resources associated with an initialized ImageSource, if any.
+// Close deletes the temporary directory at dst
+func (s *ociArchiveImageSource) Close() error {
+	defer s.tempDirRef.deleteTempDir()
+	return s.unpackedSrc.Close()
+}
+
+// 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).
+func (s *ociArchiveImageSource) GetManifest() ([]byte, string, error) {
+	return s.unpackedSrc.GetManifest()
+}
+
+func (s *ociArchiveImageSource) GetTargetManifest(digest digest.Digest) ([]byte, string, error) {
+	return s.unpackedSrc.GetTargetManifest(digest)
+}
+
+// GetBlob returns a stream for the specified blob, and the blob's size.
+func (s *ociArchiveImageSource) GetBlob(info types.BlobInfo) (io.ReadCloser, int64, error) {
+	return s.unpackedSrc.GetBlob(info)
+}
+
+func (s *ociArchiveImageSource) GetSignatures(c context.Context) ([][]byte, error) {
+	return s.unpackedSrc.GetSignatures(c)
+}