feat: update log messages to follow slog syntax (#166)

## Description

When pkg was first created we wanted to use slog because it was a
standard many implement, however consumers of pkg like Zarf and uds-cli
did not yet have proper sloggers. Now that both of these tools are using
a proper slogger, we can update this pkg to properly format it's slog
messages

---------

Signed-off-by: Austin Abro <[email protected]>

Author: AustinAbro321

oci/copier.go

@@ -39,9 +39,9 @@ func Copy(ctx context.Context, src *OrasRemote, dst *OrasRemote,
 	for idx, layer := range layers {
 		b, err := json.MarshalIndent(layer, "", "  ")
 		if err != nil {
-			src.log.Debug(fmt.Sprintf("ERROR marshalling json: %s", err.Error()))
+			src.log.Debug("failed to marshal json", "error", err.Error())
 		}
-		src.log.Debug(fmt.Sprintf("Copying layer: %s", string(b)))
+		src.log.Debug("Copying layer", "layer", string(b))
 		if err := sem.Acquire(ctx, 1); err != nil {
 			return err
 		}
@@ -52,7 +52,7 @@ func Copy(ctx context.Context, src *OrasRemote, dst *OrasRemote,
 			return err
 		}
 		if exists {
-			src.log.Debug("Layer already exists in destination, skipping")
+			src.log.Debug("layer already exists in destination, skipping")
 			b := make([]byte, layer.Size)
 			_, _ = progressBar.Write(b)
 			progressBar.Updatef("[%d/%d] layers copied", idx+1, len(layers))
@@ -106,8 +106,7 @@ func Copy(ctx context.Context, src *OrasRemote, dst *OrasRemote,
 	}
 
 	duration := time.Since(start)
-	src.log.Debug(fmt.Sprintf("Copied %s to %s with a concurrency of %d and took %s",
-		src.repo.Reference, dst.repo.Reference, concurrency, duration))
+	src.log.Debug("copy successful", "source", src.repo.Reference, "destination", dst.repo.Reference, "concurrency", concurrency, "duration", duration)
 
 	return nil
 }

oci/progress.go

@@ -26,10 +26,10 @@ func (o *OrasRemote) printLayer(desc ocispec.Descriptor, suffix string) error {
 	title := desc.Annotations[ocispec.AnnotationTitle]
 	var layerInfo string
 	if title != "" {
-		layerInfo = fmt.Sprintf("%s %s", desc.Digest.Encoded()[:12], helpers.First30last30(title))
+		layerInfo = fmt.Sprintf("%s %s", desc.Digest.Encoded()[:12], helpers.First30Last30(title))
 	} else {
 		layerInfo = fmt.Sprintf("%s [%s]", desc.Digest.Encoded()[:12], desc.MediaType)
 	}
-	o.log.Debug(fmt.Sprintf("%s (%s)", layerInfo, suffix))
+	o.log.Debug("operation successful", "layer", layerInfo, "operation", suffix)
 	return nil
 }