121 lines
4.2 KiB
Go
121 lines
4.2 KiB
Go
package source
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import (
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"bytes"
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"context"
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"encoding/json"
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"os"
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"path/filepath"
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"strings"
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"time"
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"github.com/containers/image/v5/oci/layout"
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"github.com/containers/image/v5/types"
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"github.com/opencontainers/go-digest"
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specV1 "github.com/opencontainers/image-spec/specs-go/v1"
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"github.com/pkg/errors"
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)
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// MediaTypeSourceImageConfig specifies the media type of a source-image config.
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const MediaTypeSourceImageConfig = "application/vnd.oci.source.image.config.v1+json"
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// ImageConfig specifies the config of a source image.
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type ImageConfig struct {
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// Created is the combined date and time at which the layer was created, formatted as defined by RFC 3339, section 5.6.
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Created *time.Time `json:"created,omitempty"`
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// Author is the author of the source image.
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Author string `json:"author,omitempty"`
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}
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// writeManifest writes the specified OCI `manifest` to the source image at
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// `ociDest`.
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func writeManifest(ctx context.Context, manifest *specV1.Manifest, ociDest types.ImageDestination) (*digest.Digest, int64, error) {
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rawData, err := json.Marshal(&manifest)
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if err != nil {
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return nil, -1, errors.Wrap(err, "error marshalling manifest")
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}
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if err := ociDest.PutManifest(ctx, rawData, nil); err != nil {
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return nil, -1, errors.Wrap(err, "error writing manifest")
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}
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manifestDigest := digest.FromBytes(rawData)
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return &manifestDigest, int64(len(rawData)), nil
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}
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// readManifestFromImageSource reads the manifest from the specified image
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// source. Note that the manifest is expected to be an OCI v1 manifest.
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func readManifestFromImageSource(ctx context.Context, src types.ImageSource) (*specV1.Manifest, *digest.Digest, int64, error) {
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rawData, mimeType, err := src.GetManifest(ctx, nil)
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if err != nil {
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return nil, nil, -1, err
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}
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if mimeType != specV1.MediaTypeImageManifest {
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return nil, nil, -1, errors.Errorf("image %q is of type %q (expected: %q)", strings.TrimPrefix(src.Reference().StringWithinTransport(), "//"), mimeType, specV1.MediaTypeImageManifest)
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}
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manifest := specV1.Manifest{}
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if err := json.Unmarshal(rawData, &manifest); err != nil {
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return nil, nil, -1, errors.Wrap(err, "error reading manifest")
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}
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manifestDigest := digest.FromBytes(rawData)
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return &manifest, &manifestDigest, int64(len(rawData)), nil
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}
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// readManifestFromOCIPath returns the manifest of the specified source image
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// at `sourcePath` along with its digest. The digest can later on be used to
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// locate the manifest on the file system.
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func readManifestFromOCIPath(ctx context.Context, sourcePath string) (*specV1.Manifest, *digest.Digest, int64, error) {
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ociRef, err := layout.ParseReference(sourcePath)
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if err != nil {
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return nil, nil, -1, err
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}
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ociSource, err := ociRef.NewImageSource(ctx, &types.SystemContext{})
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if err != nil {
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return nil, nil, -1, err
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}
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return readManifestFromImageSource(ctx, ociSource)
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}
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// openOrCreateSourceImage returns an OCI types.ImageDestination of the the
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// specified `sourcePath`. Note that if the path doesn't exist, it'll be
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// created along with the OCI directory layout.
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func openOrCreateSourceImage(ctx context.Context, sourcePath string) (types.ImageDestination, error) {
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ociRef, err := layout.ParseReference(sourcePath)
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if err != nil {
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return nil, err
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}
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// This will implicitly create an OCI directory layout at `path`.
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return ociRef.NewImageDestination(ctx, &types.SystemContext{})
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}
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// addConfig adds `config` to `ociDest` and returns the corresponding blob
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// info.
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func addConfig(ctx context.Context, config *ImageConfig, ociDest types.ImageDestination) (*types.BlobInfo, error) {
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rawData, err := json.Marshal(config)
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if err != nil {
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return nil, errors.Wrap(err, "error marshalling config")
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}
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info := types.BlobInfo{
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Size: -1, // "unknown": we'll get that information *after* adding
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}
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addedBlob, err := ociDest.PutBlob(ctx, bytes.NewReader(rawData), info, nil, true)
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if err != nil {
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return nil, errors.Wrap(err, "error adding config")
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}
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return &addedBlob, nil
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}
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// removeBlob removes the specified `blob` from the source image at `sourcePath`.
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func removeBlob(blob *digest.Digest, sourcePath string) error {
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blobPath := filepath.Join(filepath.Join(sourcePath, "blobs/sha256"), blob.Encoded())
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return os.Remove(blobPath)
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}
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