Control: 2.6 Ensure aufs storage driver is not used

Description

Do not use aufs as the storage driver for your Docker instance.

The aufs storage driver is the oldest storage driver used on Linux systems. It is based on a Linux kernel patch-set that is unlikely in future to be merged into the main OS kernel. The aufs driver is also known to cause some serious kernel crashes. aufs only has legacy support within systems using Docker. Most importantly, aufs is not a supported driver in many Linux distributions using latest Linux kernels and has also been deprecated with Docker Engine release 20.10.

Remediation

Do not explicitly use aufs as storage driver. For example, do not start Docker daemon as below:

dockerd --storage-driver aufs

Default Value

By default, Docker uses overlay2 as the storage driver on most of the platforms. The default storage driver can vary based on your OS vendor. You should use the storage driver that is recommended by your preferred vendor and which is in line with policy around the applications which are being deployed.