Add warning when skipping symlinks during kit pack

Print a warning log when pack skips including a symlink in order to
avoid confusing on missing files in ModelKits.

Additionally, use os.Lstat for raw files to avoid following symlinks
accidentally.

Signed-off-by: Angel Misevski <amisevsk@gmail.com>

Author: amisevsk

pkg/lib/filesystem/raw.go

@@ -38,7 +38,7 @@ import (
 func saveContentLayerAsRaw(ctx context.Context, localRepo local.LocalRepo, targetPath string, mediaType mediatype.MediaType, ignore ignore.Paths) (ocispec.Descriptor, *artifact.LayerInfo, error) {
 	targetPath = filepath.Clean(targetPath)
 
-	fi, err := os.Stat(targetPath)
+	fi, err := os.Lstat(targetPath)
 	if err != nil {
 		return ocispec.DescriptorEmptyJSON, nil, fmt.Errorf("failed to read file %s: %w", targetPath, err)
 	}

pkg/lib/filesystem/tar.go

@@ -209,17 +209,22 @@ func writeLayerToTar(basePath string, ignore ignore.Paths, tarWriter *output.Pro
 		if file == "." {
 			return nil
 		}
-		// Skip anything that's not a regular file or directory
-		if !fi.Mode().IsRegular() && !fi.Mode().IsDir() {
-			return nil
-		}
 		// Since we're walking from the context directory, we want to skip irrelevant files (e.g. sibling directories)
 		if !sameDirTree(basePath, file) {
 			if fi.IsDir() {
 				return filepath.SkipDir
 			}
 			return nil
 		}
+		// Skip anything that's not a regular file or directory
+		if !fi.Mode().IsRegular() && !fi.Mode().IsDir() {
+			if fi.Mode()&os.ModeSymlink != 0 {
+				plog.Logf(output.LogLevelWarn, "Skipping symlink %s (symlinks are not supported)", file)
+			} else {
+				plog.Debugf("Skipping file %s (not a regular file)", file)
+			}
+			return nil
+		}
 
 		// Check if file should be ignored by the ignorefile/other Kitfile layers
 		if shouldIgnore, err := ignore.Matches(file, basePath); err != nil {