docker cp是您的好友：

Usage:  docker cp [OPTIONS] CONTAINER:SRC_PATH DEST_PATH|-
docker cp [OPTIONS] SRC_PATH|- CONTAINER:DEST_PATH

Copy files/folders between a container and the local filesystem

Use '-' as the source to read a tar archive from stdin
and extract it to a directory destination in a container.
Use '-' as the destination to stream a tar archive of a
container source to stdout.

Options:
  -a, --archive       Archive mode (copy all uid/gid information)
  -L, --follow-link   Always follow symbol link in SRC_PATH

所以你可以用

docker cp <container_name>:/app /local/path/for/directory

这将把目录复制到你的本地文件系统中。在那里你可以使用一个工具来创建一个你想要的任何格式的存档。