1.2.5 Docker 17.03

Changes to the upstream Docker release cycle bring about a new versioning scheme that uses date variables (YY.MM) in the version name to indicate when a version was released upstream.

The 17.03 release includes bug fixes for the 1.13 release and does not include any major feature changes. There are several improvements to the Docker Swarm functionality.

SELinux must be set to permissive mode or disabled when running the Docker Engine while using the overlay2 storage driver.

Note that on XFS-formatted file systems, where dtype support is disabled, the default storage driver in this release is overridden from overlay2 and is set to devicemapper for compatibility reasons. Storage driver override is only implemented on fresh installations of Docker and only where the underlying file system is detected as XFS without dtype support. See Section 2.7, “Configuring Docker Storage” for more information.

The upstream default storage driver for Docker was changed from devicemapper to overlay2. This change can cause problems on systems where overlay is used in conjunction with a file system that does not have dtype support enabled. Since the root partition on Oracle Linux 7 is automatically formatted with -n ftype=0 (disabling dtype support), where XFS is selected as the file system, the package installer checks the filesystem for dtype support and if this is not enabled the default storage driver is set to use devicemapper. This ensures that Docker is ready-to-use on newly installed systems and is achieved by setting the storage driver in the storage options in /etc/sysconfig/docker-storage.

It is possible to reconfigure Docker to use an alternate storage driver, by using the --storage-driver flag when running the Docker Engine daemon, or by setting the storage-driver option in the daemon.json configuration file. Oracle recommends that you use dedicated storage, formatted using Btrfs, for Docker. If you intend to use the overlay2 storage driver with an XFS-formatted file system, you must ensure that dtype support is enabled. See Section 2.7, “Configuring Docker Storage” for more information. Remember that if you wish to change the storage driver from devicemapper, you must remove the option set in /etc/sysconfig/docker-storage.

Other improvements were made to the Docker remote API and to the Docker client to add consistency to the command set. Also runtime improvements were made to the Docker Engine. Further developments on Docker Swarm mode are also noted.