Edit the manifest when pushing uncompressed data from c/storage

copy/compression.go

@@ -70,14 +70,27 @@ func blobPipelineDetectCompressionStep(stream *sourceStream, srcInfo types.BlobI
 
 // bpCompressionStepData contains data that the copy pipeline needs about the compression step.
 type bpCompressionStepData struct {
-	operation              types.LayerCompression      // Operation to use for updating the blob metadata.
+	operation              bpcOperation                // What we are actually doing
+	uploadedOperation      types.LayerCompression      // Operation to use for updating the blob metadata (matching the end state, not necessarily what we do)
 	uploadedAlgorithm      *compressiontypes.Algorithm // An algorithm parameter for the compressionOperation edits.
 	uploadedAnnotations    map[string]string           // Annotations that should be set on the uploaded blob. WARNING: This is only set after the srcStream.reader is fully consumed.
 	srcCompressorName      string                      // Compressor name to record in the blob info cache for the source blob.
 	uploadedCompressorName string                      // Compressor name to record in the blob info cache for the uploaded blob.
 	closers                []io.Closer                 // Objects to close after the upload is done, if any.
 }
 
+type bpcOperation int
+
+const (
+	bpcOpInvalid              bpcOperation = iota
+	bpcOpPreserveOpaque                    // We are preserving something where compression is not applicable
+	bpcOpPreserveCompressed                // We are preserving a compressed, and decompressible, layer
+	bpcOpPreserveUncompressed              // We are preserving an uncompressed, and compressible, layer
+	bpcOpCompressUncompressed              // We are compressing uncompressed data
+	bpcOpRecompressCompressed              // We are recompressing compressed data
+	bpcOpDecompressCompressed              // We are decompressing compressed data
+)
+
 // blobPipelineCompressionStep updates *stream to compress and/or decompress it.
 // srcInfo is primarily used for error messages.
 // Returns data for other steps; the caller should eventually call updateCompressionEdits and perhaps recordValidatedBlobData,
@@ -112,10 +125,11 @@ func (ic *imageCopier) blobPipelineCompressionStep(stream *sourceStream, canModi
 // bpcPreserveEncrypted checks if the input is encrypted, and returns a *bpCompressionStepData if so.
 func (ic *imageCopier) bpcPreserveEncrypted(stream *sourceStream, _ bpDetectCompressionStepData) (*bpCompressionStepData, error) {
 	if isOciEncrypted(stream.info.MediaType) {
+		// We can’t do anything with an encrypted blob unless decrypted.
 		logrus.Debugf("Using original blob without modification for encrypted blob")
-		// PreserveOriginal due to any compression not being able to be done on an encrypted blob unless decrypted
 		return &bpCompressionStepData{
-			operation:              types.PreserveOriginal,
+			operation:              bpcOpPreserveOpaque,
+			uploadedOperation:      types.PreserveOriginal,
 			uploadedAlgorithm:      nil,
 			srcCompressorName:      internalblobinfocache.UnknownCompression,
 			uploadedCompressorName: internalblobinfocache.UnknownCompression,
@@ -143,7 +157,8 @@ func (ic *imageCopier) bpcCompressUncompressed(stream *sourceStream, detected bp
 			Size:   -1,
 		}
 		return &bpCompressionStepData{
-			operation:              types.Compress,
+			operation:              bpcOpCompressUncompressed,
+			uploadedOperation:      types.Compress,
 			uploadedAlgorithm:      uploadedAlgorithm,
 			uploadedAnnotations:    annotations,
 			srcCompressorName:      detected.srcCompressorName,
@@ -182,7 +197,8 @@ func (ic *imageCopier) bpcRecompressCompressed(stream *sourceStream, detected bp
 		}
 		succeeded = true
 		return &bpCompressionStepData{
-			operation:              types.PreserveOriginal,
+			operation:              bpcOpRecompressCompressed,
+			uploadedOperation:      types.PreserveOriginal,
 			uploadedAlgorithm:      ic.compressionFormat,
 			uploadedAnnotations:    annotations,
 			srcCompressorName:      detected.srcCompressorName,
@@ -208,7 +224,8 @@ func (ic *imageCopier) bpcDecompressCompressed(stream *sourceStream, detected bp
 			Size:   -1,
 		}
 		return &bpCompressionStepData{
-			operation:              types.Decompress,
+			operation:              bpcOpDecompressCompressed,
+			uploadedOperation:      types.Decompress,
 			uploadedAlgorithm:      nil,
 			srcCompressorName:      detected.srcCompressorName,
 			uploadedCompressorName: internalblobinfocache.Uncompressed,
@@ -232,14 +249,26 @@ func (ic *imageCopier) bpcPreserveOriginal(_ *sourceStream, detected bpDetectCom
 	// But don’t touch blobs in objects where we can’t change compression,
 	// so that src.UpdatedImage() doesn’t fail; assume that for such blobs
 	// LayerInfosForCopy() should not be making any changes in the first place.
+	var bpcOp bpcOperation
+	var uploadedOp types.LayerCompression
 	var algorithm *compressiontypes.Algorithm
-	if layerCompressionChangeSupported && detected.isCompressed {
+	switch {
+	case !layerCompressionChangeSupported:
+		bpcOp = bpcOpPreserveOpaque
+		uploadedOp = types.PreserveOriginal
+		algorithm = nil
+	case detected.isCompressed:
+		bpcOp = bpcOpPreserveCompressed
+		uploadedOp = types.PreserveOriginal
 		algorithm = &detected.format
-	} else {
+	default:
+		bpcOp = bpcOpPreserveUncompressed
+		uploadedOp = types.Decompress
 		algorithm = nil
 	}
 	return &bpCompressionStepData{
-		operation:              types.PreserveOriginal,
+		operation:              bpcOp,
+		uploadedOperation:      uploadedOp,
 		uploadedAlgorithm:      algorithm,
 		srcCompressorName:      detected.srcCompressorName,
 		uploadedCompressorName: detected.srcCompressorName,
@@ -248,7 +277,7 @@ func (ic *imageCopier) bpcPreserveOriginal(_ *sourceStream, detected bpDetectCom
 
 // updateCompressionEdits sets *operation, *algorithm and updates *annotations, if necessary.
 func (d *bpCompressionStepData) updateCompressionEdits(operation *types.LayerCompression, algorithm **compressiontypes.Algorithm, annotations *map[string]string) {
-	*operation = d.operation
+	*operation = d.uploadedOperation
 	// If we can modify the layer's blob, set the desired algorithm for it to be set in the manifest.
 	*algorithm = d.uploadedAlgorithm
 	if *annotations == nil {
@@ -257,7 +286,8 @@ func (d *bpCompressionStepData) updateCompressionEdits(operation *types.LayerCom
 	maps.Copy(*annotations, d.uploadedAnnotations)
 }
 
-// recordValidatedBlobData updates b.blobInfoCache with data about the created uploadedInfo adnd the original srcInfo.
+// recordValidatedBlobData updates b.blobInfoCache with data about the created uploadedInfo (as returned by PutBlob)
+// and the original srcInfo (which the caller guarantees has been validated).
 // This must ONLY be called if all data has been validated by OUR code, and is not coming from third parties.
 func (d *bpCompressionStepData) recordValidatedDigestData(c *copier, uploadedInfo types.BlobInfo, srcInfo types.BlobInfo,
 	encryptionStep *bpEncryptionStepData, decryptionStep *bpDecryptionStepData) error {
@@ -268,17 +298,26 @@ func (d *bpCompressionStepData) recordValidatedDigestData(c *copier, uploadedInf
 	// in the blob info cache (which would probably be necessary for any more complex logic),
 	// and the simplicity is attractive.
 	if !encryptionStep.encrypting && !decryptionStep.decrypting {
-		// If d.operation != types.PreserveOriginal, we now have two reliable digest values:
+		// If d.operation != bpcOpPreserve*, we now have two reliable digest values:
 		// srcinfo.Digest describes the pre-d.operation input, verified by digestingReader
 		// uploadedInfo.Digest describes the post-d.operation output, computed by PutBlob
-		// (because stream.info.Digest == "", this must have been computed afresh).
+		// (because we set stream.info.Digest == "", this must have been computed afresh).
 		switch d.operation {
-		case types.PreserveOriginal:
-			break // Do nothing, we have only one digest and we might not have even verified it.
-		case types.Compress:
+		case bpcOpPreserveOpaque:
+			// No useful information
+		case bpcOpCompressUncompressed:
 			c.blobInfoCache.RecordDigestUncompressedPair(uploadedInfo.Digest, srcInfo.Digest)
-		case types.Decompress:
+		case bpcOpDecompressCompressed:
 			c.blobInfoCache.RecordDigestUncompressedPair(srcInfo.Digest, uploadedInfo.Digest)
+		case bpcOpRecompressCompressed, bpcOpPreserveCompressed:
+			// We know one or two compressed digests. BlobInfoCache associates compression variants via the uncompressed digest,
+			// and we don’t know that one.
+			// That also means that repeated copies with the same recompression don’t identify reuse opportunities (unless
+			// RecordDigestUncompressedPair was called for both compressed variants for some other reason).
+		case bpcOpPreserveUncompressed:
+			c.blobInfoCache.RecordDigestUncompressedPair(srcInfo.Digest, srcInfo.Digest)
+		case bpcOpInvalid:
+			fallthrough
 		default:
 			return fmt.Errorf("Internal error: Unexpected d.operation value %#v", d.operation)
 		}

copy/single.go

@@ -383,7 +383,7 @@ func (ic *imageCopier) compareImageDestinationManifestEqual(ctx context.Context,
 
 	compressionAlgos := set.New[string]()
 	for _, srcInfo := range ic.src.LayerInfos() {
-		if c := compressionAlgorithmFromMIMEType(srcInfo); c != nil {
+		if _, c := compressionEditsFromMIMEType(srcInfo); c != nil {
 			compressionAlgos.Add(c.Name())
 		}
 	}
@@ -636,17 +636,22 @@ type diffIDResult struct {
 	err    error
 }
 
-func compressionAlgorithmFromMIMEType(srcInfo types.BlobInfo) *compressiontypes.Algorithm {
+// compressionEditsFromMIMEType returns a (CompressionOperation, CompressionAlgorithm) value pair suitable
+// for types.BlobInfo, based on a MIME type of srcInfo.
+func compressionEditsFromMIMEType(srcInfo types.BlobInfo) (types.LayerCompression, *compressiontypes.Algorithm) {
 	// This MIME type → compression mapping belongs in manifest-specific code in our manifest
 	// package (but we should preferably replace/change UpdatedImage instead of productizing
 	// this workaround).
 	switch srcInfo.MediaType {
 	case manifest.DockerV2Schema2LayerMediaType, imgspecv1.MediaTypeImageLayerGzip:
-		return &compression.Gzip
+		return types.PreserveOriginal, &compression.Gzip
 	case imgspecv1.MediaTypeImageLayerZstd:
-		return &compression.Zstd
+		return types.PreserveOriginal, &compression.Zstd
+	case manifest.DockerV2SchemaLayerMediaTypeUncompressed, imgspecv1.MediaTypeImageLayer:
+		return types.Decompress, nil
+	default:
+		return types.PreserveOriginal, nil
 	}
-	return nil
 }
 
 // copyLayer copies a layer with srcInfo (with known Digest and Annotations and possibly known Size) in src to dest, perhaps (de/re/)compressing it,
@@ -660,8 +665,8 @@ func (ic *imageCopier) copyLayer(ctx context.Context, srcInfo types.BlobInfo, to
 	// which uses the compression information to compute the updated MediaType values.
 	// (Sadly UpdatedImage() is documented to not update MediaTypes from
 	//  ManifestUpdateOptions.LayerInfos[].MediaType, so we are doing it indirectly.)
-	if srcInfo.CompressionAlgorithm == nil {
-		srcInfo.CompressionAlgorithm = compressionAlgorithmFromMIMEType(srcInfo)
+	if srcInfo.CompressionOperation == types.PreserveOriginal && srcInfo.CompressionAlgorithm == nil {
+		srcInfo.CompressionOperation, srcInfo.CompressionAlgorithm = compressionEditsFromMIMEType(srcInfo)
 	}
 
 	ic.c.printCopyInfo("blob", srcInfo)

types/types.go

@@ -135,8 +135,8 @@ type BlobInfo struct {
 	// CompressionOperation is used in Image.UpdateLayerInfos to instruct
 	// whether the original layer's "compressed or not" should be preserved,
 	// possibly while changing the compression algorithm from one to another,
-	// or if it should be compressed or decompressed.  The field defaults to
-	// preserve the original layer's compressedness.
+	// or if it should be changed to compressed or decompressed.
+	// The field defaults to preserve the original layer's compressedness.
 	// TODO: To remove together with CryptoOperation in re-design to remove
 	// field out of BlobInfo.
 	CompressionOperation LayerCompression