Log kaniko errors that happen during the tar phase

pkg/skaffold/build/cluster/kaniko.go

@@ -102,12 +102,14 @@ func (b *Builder) copyKanikoBuildContext(ctx context.Context, workspace string,
 		return fmt.Errorf("waiting for pod to initialize: %w", err)
 	}
 
+	errs := make(chan error, 1)
 	buildCtx, buildCtxWriter := io.Pipe()
 	go func() {
 		err := docker.CreateDockerTarContext(ctx, buildCtxWriter, docker.NewBuildConfig(
 			workspace, artifactName, artifact.DockerfilePath, artifact.BuildArgs), b.cfg)
 		if err != nil {
 			buildCtxWriter.CloseWithError(fmt.Errorf("creating docker context: %w", err))
+			errs <- err
 			return
 		}
 		buildCtxWriter.Close()
@@ -117,7 +119,12 @@ func (b *Builder) copyKanikoBuildContext(ctx context.Context, workspace string,
 	// In case of an error, print the command's output. (The `err` itself is useless: exit status 1).
 	var out bytes.Buffer
 	if err := b.kubectlcli.Run(ctx, buildCtx, &out, "exec", "-i", podName, "-c", initContainer, "-n", b.Namespace, "--", "tar", "-xf", "-", "-C", kaniko.DefaultEmptyDirMountPath); err != nil {
-		return fmt.Errorf("uploading build context: %s", out.String())
+		errRun := fmt.Errorf("uploading build context: %s", out.String())
+		errTar := <-errs
+		if errTar != nil {
+			errRun = fmt.Errorf("%v\ntar errors: %w", errRun, errTar)
+		}
+		return errRun
 	}
 
 	// Generate a file to successfully terminate the init container.