Return a precise reference to the created image when writing to conta…

…iners-storage

Signed-off-by: Miloslav Trmač <mitr@redhat.com>

copy/copy.go

@@ -137,6 +137,16 @@ type Options struct {
 	// DestinationCtx.CompressionFormat is used exclusively, and blobs of other
 	// compression algorithms are not reused.
 	ForceCompressionFormat bool
+
+	// ReportResolvedReference, if set, asks the destination transport to store
+	// a “resolved” (more detailed) reference to the created image
+	// into the value this option points to.
+	// What “resolved” means is transport-specific.
+	// Most transports don’t support this, and cause the value to be set to nil.
+	//
+	// For the containers-storage: transport, the reference contains an image ID,
+	// so that storage.ResolveReference returns exactly the created image.
+	ReportResolvedReference *types.ImageReference
 }
 
 // OptionCompressionVariant allows to supply information about
@@ -337,8 +347,12 @@ func Image(ctx context.Context, policyContext *signature.PolicyContext, destRef,
 		}
 	}
 
+	if options.ReportResolvedReference != nil {
+		*options.ReportResolvedReference = nil // The default outcome, if not specifically supported by the transport.
+	}
 	if err := c.dest.CommitWithOptions(ctx, private.CommitOptions{
-		UnparsedToplevel: c.unparsedToplevel,
+		UnparsedToplevel:        c.unparsedToplevel,
+		ReportResolvedReference: options.ReportResolvedReference,
 	}); err != nil {
 		return nil, fmt.Errorf("committing the finished image: %w", err)
 	}

internal/private/private.go

@@ -158,6 +158,11 @@ type CommitOptions struct {
 	// if PutManifest was only called for the single-arch image with instanceDigest == nil), primarily to allow lookups by the
 	// original manifest list digest, if desired.
 	UnparsedToplevel types.UnparsedImage
+	// ReportResolvedReference, if set, asks the transport to store a “resolved” (more detailed) reference to the created image
+	// into the value this option points to.
+	// What “resolved” means is transport-specific.
+	// Transports which don’t support reporting resolved references can ignore the field; the generic copy code writes "nil" into the value.
+	ReportResolvedReference *types.ImageReference
 }
 
 // ImageSourceChunk is a portion of a blob.

storage/storage_dest.go

@@ -1343,6 +1343,13 @@ func (s *storageImageDestination) CommitWithOptions(ctx context.Context, options
 		}
 		logrus.Debugf("added name %q to image %q", name, img.ID)
 	}
+	if options.ReportResolvedReference != nil {
+		resolved, err := newReference(s.imageRef.transport, s.imageRef.named, intendedID)
+		if err != nil {
+			return fmt.Errorf("creating a resolved reference for (%s, %s): %w", s.imageRef.StringWithinTransport(), intendedID, err)
+		}
+		*options.ReportResolvedReference = resolved
+	}
 
 	commitSucceeded = true
 	return nil