这些文件不是构建(最终结果)图像的一部分.

Those files are not part of the built (end-result) image.

它们是传递给守护进程在构建过程中，供 Dockerfile 指令使用，例如 添加 或 COPY 或 RUN.

They are part of the build context passed to the daemon during the build process, to be used by Dockerfile directives like ADD or COPY or RUN.

构建的上下文是位于指定 PATH 或 URL

A build’s context is the files located in the specified PATH or URL

例如，运行此命令以使用分支容器中名为 docker 的目录:

For example, run this command to use a directory called docker in the branch container:

$ docker build https://github.com/docker/rootfs.git#container:docker

这是由 Context 和 ModifiableContext.

This is managed by Context and ModifiableContext.