The `devicemapper` storage driver is deprecated in favor of `overlay2`, and will
be removed in a future release. Users of the `devicemapper` storage driver are
recommended to migrate to a different storage driver, such as `overlay2`, which
is now the default storage driver.

The `devicemapper` storage driver facilitates running Docker on older (3.x) kernels
that have no support for other storage drivers (such as overlay2, or AUFS).

Now that support for `overlay2` is added to all supported distros (as they are
either on kernel 4.x, or have support for multiple lowerdirs backported), there
is no reason to continue maintenance of the `devicemapper` storage driver.

Signed-off-by: Sebastiaan van Stijn <[email protected]>
(cherry picked from commit 06fcabb)
Signed-off-by: Sebastiaan van Stijn <[email protected]>

The `overlay` storage driver is deprecated in favor of the `overlay2` storage
driver, which has all the benefits of `overlay`, without its limitations (excessive
inode consumption). The legacy `overlay` storage driver will be removed in a future
release. Users of the `overlay` storage driver should migrate to the `overlay2`
storage driver.

The legacy `overlay` storage driver allowed using overlayFS-backed filesystems
on pre 4.x kernels. Now that all supported distributions are able to run `overlay2`
(as they are either on kernel 4.x, or have support for multiple lowerdirs
backported), there is no reason to keep maintaining the `overlay` storage driver.

Signed-off-by: Sebastiaan van Stijn <[email protected]>
(cherry picked from commit 31be4e0)
Signed-off-by: Sebastiaan van Stijn <[email protected]>

Discourage users from using deprecated storage-drivers
by skipping them when automatically selecting a storage-
driver.

This change does not affect existing installations, because
existing state will take precedence.

Users can still use deprecated drivers by manually configuring
the daemon to use a specific driver.

Signed-off-by: Sebastiaan van Stijn <[email protected]>
(cherry picked from commit b72db8b)