better error wrapping and add more tests for copy

pkg/commands/add.go

@@ -21,6 +21,7 @@ import (
 
 	v1 "github.com/google/go-containerregistry/pkg/v1"
 	"github.com/moby/buildkit/frontend/dockerfile/instructions"
+	"github.com/pkg/errors"
 
 	"github.com/GoogleContainerTools/kaniko/pkg/dockerfile"
 
@@ -66,18 +67,18 @@ func (a *AddCommand) ExecuteCommand(config *v1.Config, buildArgs *dockerfile.Bui
 			}
 			logrus.Infof("Adding remote URL %s to %s", src, urlDest)
 			if err := util.DownloadFileToDest(src, urlDest); err != nil {
-				return err
+				return errors.Wrap(err, "downloading remote source file")
 			}
 			a.snapshotFiles = append(a.snapshotFiles, urlDest)
 		} else if util.IsFileLocalTarArchive(fullPath) {
 			tarDest, err := util.DestinationFilepath("", dest, config.WorkingDir)
 			if err != nil {
-				return err
+				return errors.Wrap(err, "determining dest for tar")
 			}
 			logrus.Infof("Unpacking local tar archive %s to %s", src, tarDest)
 			extractedFiles, err := util.UnpackLocalTarArchive(fullPath, tarDest)
 			if err != nil {
-				return err
+				return errors.Wrap(err, "unpacking local tar")
 			}
 			logrus.Debugf("Added %v from local tar archive %s", extractedFiles, src)
 			a.snapshotFiles = append(a.snapshotFiles, extractedFiles...)
@@ -98,7 +99,7 @@ func (a *AddCommand) ExecuteCommand(config *v1.Config, buildArgs *dockerfile.Bui
 	}
 
 	if err := copyCmd.ExecuteCommand(config, buildArgs); err != nil {
-		return err
+		return errors.Wrap(err, "executing copy command")
 	}
 	a.snapshotFiles = append(a.snapshotFiles, copyCmd.snapshotFiles...)
 	return nil

pkg/commands/copy.go

@@ -54,18 +54,23 @@ func (c *CopyCommand) ExecuteCommand(config *v1.Config, buildArgs *dockerfile.Bu
 
 	uid, gid, err := getUserGroup(c.cmd.Chown, replacementEnvs)
 	if err != nil {
-		return err
+		return errors.Wrap(err, "getting user group from chowm")
 	}
 
 	srcs, dest, err := util.ResolveEnvAndWildcards(c.cmd.SourcesAndDest, c.buildcontext, replacementEnvs)
 	if err != nil {
-		return err
+		return errors.Wrap(err, "resolving src")
 	}
 
 	// For each source, iterate through and copy it over
 	for _, src := range srcs {
 		fullPath := filepath.Join(c.buildcontext, src)
-		fi, err := os.Lstat(fullPath)
+		srcPath, err := resolveIfSymlink(fullPath)
+		if err != nil {
+			return errors.Wrap(err, "resolving src symlink")
+		}
+
+		fi, err := os.Lstat(srcPath)
 		if err != nil {
 			return errors.Wrap(err, "could not copy source")
 		}
@@ -79,26 +84,27 @@ func (c *CopyCommand) ExecuteCommand(config *v1.Config, buildArgs *dockerfile.Bu
 
 		destPath, err := util.DestinationFilepath(fullPath, dest, cwd)
 		if err != nil {
-			return err
+			return errors.Wrap(err, "find destination path")
+		}
+
+		// If the destination dir is a symlink we need to resolve the path and use
+		// that instead of the symlink path
+		destPath, err = resolveIfSymlink(destPath)
+		if err != nil {
+			return errors.Wrap(err, "resolving dest symlink")
 		}
 
 		if fi.IsDir() {
-			// If the destination dir is a symlink we need to resolve the path and use
-			// that instead of the symlink path
-			destPath, err = resolveIfSymlink(destPath)
-			if err != nil {
-				return err
-			}
 			copiedFiles, err := util.CopyDir(fullPath, destPath, c.buildcontext, uid, gid)
 			if err != nil {
-				return err
+				return errors.Wrap(err, "copying dir")
 			}
 			c.snapshotFiles = append(c.snapshotFiles, copiedFiles...)
 		} else if util.IsSymlink(fi) {
 			// If file is a symlink, we want to copy the target file to destPath
-			exclude, err := util.CopySymlink(fullPath, destPath, c.buildcontext, uid, gid)
+			exclude, err := util.CopySymlink(fullPath, destPath, c.buildcontext, uid, gid, false)
 			if err != nil {
-				return err
+				return errors.Wrap(err, "copying symlink")
 			}
 			if exclude {
 				continue
@@ -108,7 +114,7 @@ func (c *CopyCommand) ExecuteCommand(config *v1.Config, buildArgs *dockerfile.Bu
 			// ... Else, we want to copy over a file
 			exclude, err := util.CopyFile(fullPath, destPath, c.buildcontext, uid, gid)
 			if err != nil {
-				return err
+				return errors.Wrap(err, "copying file")
 			}
 			if exclude {
 				continue