If a volume is mounted on top of an existing directory in the container, docker export will export the contents of the underlying directory, not the contents of the volume. Refer to Backup, restore, or migrate data volumes in the user guide for examples on exporting data in a volume.
Docker export and import container
export works with Docker #containers, and it exports a snapshot of the container's file system. Use this command if you want to share or back up the result of building an image. import works with the file system of an exported container, and it imports it as a #Docker image.
How do I import and export images from Docker?