Function writeContentsForImage

pkg/imgutil/commit/commit.go:300–382

writeContentsForImage will commit oci image config and manifest into containerd's content store.

(ctx context.Context, snName string, baseImg containerd.Image, newConfig ocispec.Image, diffLayerDesc ocispec.Descriptor, opts *Opts)

// writeContentsForImage will commit oci image config and manifest into containerd's content store.
func writeContentsForImage(ctx context.Context, snName string, baseImg containerd.Image, newConfig ocispec.Image, diffLayerDesc ocispec.Descriptor, opts *Opts) (ocispec.Descriptor, digest.Digest, error) {
	newConfigJSON, err := json.Marshal(newConfig)
	if err != nil {
		return ocispec.Descriptor{}, emptyDigest, err
	}

	// Select media types based on format choice
	var configMediaType, manifestMediaType string
	switch opts.Format {
	case types.ImageFormatOCI:
		configMediaType = ocispec.MediaTypeImageConfig
		manifestMediaType = ocispec.MediaTypeImageManifest
	case types.ImageFormatDocker:
		configMediaType = images.MediaTypeDockerSchema2Config
		manifestMediaType = images.MediaTypeDockerSchema2Manifest
	default:
		// Default to Docker Schema2 for compatibility
		configMediaType = images.MediaTypeDockerSchema2Config
		manifestMediaType = images.MediaTypeDockerSchema2Manifest
	}

	configDesc := ocispec.Descriptor{
		MediaType: configMediaType,
		Digest:    digest.FromBytes(newConfigJSON),
		Size:      int64(len(newConfigJSON)),
	}

	cs := baseImg.ContentStore()
	baseMfst, _, err := imgutil.ReadManifest(ctx, baseImg)
	if err != nil {
		return ocispec.Descriptor{}, emptyDigest, err
	}
	layers := append(baseMfst.Layers, diffLayerDesc)

	newMfst := struct {
		MediaType string `json:"mediaType,omitempty"`
		ocispec.Manifest
	}{
		MediaType: manifestMediaType,
		Manifest: ocispec.Manifest{
			Versioned: specs.Versioned{
				SchemaVersion: 2,
			},
			Config: configDesc,
			Layers: layers,
		},
	}

	newMfstJSON, err := json.MarshalIndent(newMfst, "", "    ")
	if err != nil {
		return ocispec.Descriptor{}, emptyDigest, err
	}

	newMfstDesc := ocispec.Descriptor{
		MediaType: manifestMediaType,
		Digest:    digest.FromBytes(newMfstJSON),
		Size:      int64(len(newMfstJSON)),
	}