copy: implement instanceCopyClone for zstd compression

* copy.Options now contains a new field `EnsureCompressionVariantExists map[string]int` which allows users to specify if they want to clone images with specified `compression`. * copyMultipleImages now implements `instanceCopyClone` and extends function specifically for `zstd` compression. Signed-off-by: Aditya R <[email protected]>
containers · Jun 7, 2023 · 805cb83 · 805cb83
1 parent 8c21415
commit 805cb83
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Showing 2 changed files with 61 additions and 4 deletions.
diff --git a/copy/copy.go b/copy/copy.go
@@ -126,6 +126,10 @@ type Options struct {
 	// Download layer contents with "nondistributable" media types ("foreign" layers) and translate the layer media type
 	// to not indicate "nondistributable".
 	DownloadForeignLayers bool
+
+	// Contains a map of compression algorithm and compression level, where c/image will ensure that selected
+	// images in the manifest list will be replicated with provided compression algorithms.
+	EnsureCompressionVariantExists map[string]int
 }
 
 // copier allows us to keep track of diffID values for blobs, and other

diff --git a/copy/multiple.go b/copy/multiple.go
@@ -11,7 +11,9 @@ import (
 	"github.com/containers/image/v5/internal/image"
 	internalManifest "github.com/containers/image/v5/internal/manifest"
 	"github.com/containers/image/v5/manifest"
+	"github.com/containers/image/v5/pkg/compression"
 	"github.com/containers/image/v5/signature"
+	"github.com/containers/image/v5/transports"
 	digest "github.com/opencontainers/go-digest"
 	imgspecv1 "github.com/opencontainers/image-spec/specs-go/v1"
 	"github.com/sirupsen/logrus"
@@ -28,6 +30,7 @@ const (
 type instanceCopy struct {
 	op           instanceCopyKind
 	sourceDigest digest.Digest
+	forceZstd    bool
 }
 
 // prepareInstanceCopies prepares a list of instances which needs to copied to the manifest list.
@@ -39,8 +42,15 @@ func prepareInstanceCopies(instanceDigests []digest.Digest, options *Options) []
 			logrus.Debugf("Skipping instance %s (%d/%d)", instanceDigest, i+1, len(instanceDigests))
 			continue
 		}
+		operation := instanceCopyCopy
+		forceZstd := false
+		if _, ok := options.EnsureCompressionVariantExists["zstd"]; ok {
+			operation = instanceCopyClone
+			forceZstd = true
+		}
 		res = append(res, instanceCopy{
-			op:           instanceCopyCopy,
+			op:           operation,
+			forceZstd:    forceZstd,
 			sourceDigest: instanceDigest,
 		})
 	}
@@ -124,8 +134,9 @@ func (c *copier) copyMultipleImages(ctx context.Context, policyContext *signatur
 	for i, instance := range instanceCopyList {
 		// Update instances to be edited by their `ListOperation` and
 		// populate necessary fields.
-		switch instance.op {
-		case instanceCopyCopy:
+		processedOp := false
+		if instance.op == instanceCopyCopy || instance.op == instanceCopyClone {
+			processedOp = true
 			logrus.Debugf("Copying instance %s (%d/%d)", instance.sourceDigest, i+1, len(instanceCopyList))
 			c.Printf("Copying image %s (%d/%d)\n", instance.sourceDigest, i+1, len(instanceCopyList))
 			unparsedInstance := image.UnparsedInstance(c.rawSource, &instanceCopyList[i].sourceDigest)
@@ -140,7 +151,49 @@ func (c *copier) copyMultipleImages(ctx context.Context, policyContext *signatur
 				UpdateDigest:    updatedManifestDigest,
 				UpdateSize:      int64(len(updatedManifest)),
 				UpdateMediaType: updatedManifestType})
-		default:
+		}
+		if instance.op == instanceCopyClone {
+			processedOp = false
+			c.Printf("Replicating image %s (%d/%d)\n", instance.sourceDigest, i+1, len(instanceCopyList))
+			c.Printf("Replicating image %s (%d/%d)\n", instance.sourceDigest, i+1, len(instanceCopyList))
+			unparsedInstance := image.UnparsedInstance(c.rawSource, &instanceCopyList[i].sourceDigest)
+			src, err := image.FromUnparsedImage(ctx, options.SourceCtx, unparsedInstance)
+			if err != nil {
+				return nil, fmt.Errorf("initializing image from source %s: %w", transports.ImageName(c.rawSource.Reference()), err)
+			}
+			imgConfig, err := src.OCIConfig(ctx)
+			if err != nil {
+				return nil, fmt.Errorf("parsing image configuration: %w", err)
+			}
+			imgPlatform := imgspecv1.Platform{Architecture: imgConfig.Architecture,
+				OS:         imgConfig.OS,
+				OSVersion:  imgConfig.OSVersion,
+				OSFeatures: imgConfig.OSFeatures,
+				Variant:    imgConfig.Variant}
+			addAnnotations := make(map[string]string)
+			if instance.forceZstd {
+				// add `zstd` annotation
+				addAnnotations[internalManifest.OCI1InstanceAnnotationCompressionZSTD] = "true"
+				// copy options with new compression format
+				optionsClone := options
+				optionsClone.DestinationCtx.CompressionFormat = &compression.Zstd
+				compressionLevel := options.EnsureCompressionVariantExists["zstd"]
+				options.DestinationCtx.CompressionLevel = &compressionLevel
+			}
+			addManifest, addManifestType, addManifestDigest, err := c.copySingleImage(ctx, policyContext, options, unparsedToplevel, unparsedInstance, &instanceCopyList[i].sourceDigest)
+			if err != nil {
+				return nil, fmt.Errorf("Replicating image %d/%d from manifest list: %w", i+1, len(instanceCopyList), err)
+			}
+			// Record the result of a possible conversion here.
+			instanceEdits = append(instanceEdits, internalManifest.ListEdit{
+				ListOperation:  internalManifest.ListOpAdd,
+				AddDigest:      addManifestDigest,
+				AddSize:        int64(len(addManifest)),
+				AddMediaType:   addManifestType,
+				AddAnnotations: addAnnotations,
+				AddPlatform:    &imgPlatform})
+		}
+		if !processedOp {
 			return nil, fmt.Errorf("copying image: invalid copy operation %d", instance.op)
 		}
 	}