UnionFS: UnionFS is a layered, lightweight, and high-performance file system that allows changes to the file system to be layered on top of each other as a single commit. Unite several directories into a single virtual filesystem. The Union file system is the basis for Docker images. Images can be inherited by layers, and specific application images can be created based on the base image (without a parent image).



Feature: Multiple file systems are loaded simultaneously, but only one file system can be seen from the outside. Joint loading adds all layers of file systems together, so that the final file system contains all the underlying files and directories