Start api directory, which will become a module.

api/filesys/rpath.go

@@ -0,0 +1,12 @@
+// Copyright 2019 The Kubernetes Authors.
+// SPDX-License-Identifier: Apache-2.0
+
+package filesys
+
+import "path/filepath"
+
+// RootedPath returns a rooted path, e.g. "/foo/bar" as
+// opposed to "foo/bar".
+func RootedPath(elem ...string) string {
+	return separator + filepath.Join(elem...)
+}