Comment 2 for bug 1722522

Reviewed: https://review.openstack.org/510882
Committed: https://git.openstack.org/cgit/openstack/magnum/commit/?id=28fff8006ae17d9afeee4ad409e12b6608fa26cb
Submitter: Zuul
Branch: master

commit 28fff8006ae17d9afeee4ad409e12b6608fa26cb
Author: Ricardo Rocha <email address hidden>
Date: Tue Oct 10 13:17:51 2017 +0000

    Make docker_storage_driver a str instead of enum

    Allow any value to be passed on the docker_storage_driver field by turning it
    into a StringField (was EnumField), and remove the constraints limiting the
    values to 'devicemapper' and 'overlay'.

    Change the docker storage setup to have a generic setup for all drivers with
    the exception of 'devicemapper', which keeps its own specific storage config
    function. For all others, do the same we already did for overlay (with two
    cases for usage of a cinder volume or not) and simply set the storage driver
    in the docker configuration to the value provided in the cluster template.

    Change-Id: I9aa8f232ce64ece4d439c0a476f463820a499617
    Closes-Bug: #1722522