Comment 4 for bug 1856556

Reviewed: https://review.opendev.org/699986
Committed: https://git.openstack.org/cgit/openstack/cinderlib/commit/?id=199ebd4f5a1984573877f582a2655f4171916761
Submitter: Zuul
Branch: stable/train

commit 199ebd4f5a1984573877f582a2655f4171916761
Author: Gorka Eguileor <email address hidden>
Date: Wed Dec 18 17:48:16 2019 +0100

    Fix configuration options

    When fixing bug #1854188 (Change-ID:
    I62e992804a3ae6aa0b4aa4f883807783197d4b33) we broke configuration
    options, because now we cannot pass configuration options from the
    DEFAULT section, and some ListOpt don't work because cinderlib was
    incorrectly expecting all these options to have bounds=True, but some
    don't define it and default to False.

    Most of the "crazy" code we currently have around oslo config is because
    we wanted to support drivers that add configuration options on runtime
    and reload the configuration.

    This made sense when cinderlib was not an OpenStack official project,
    but now that it is it makes more sense to force Cinder drivers to do the
    right thing.

    Aligned with this, this patch removes all the faking of the cinder.conf
    file as a StringIO object, and simply sets things in the configuration
    object that is passed to the drivers, which is the only thing they
    should be using.

    This will make cinderlib code more robust, even if some drivers will now
    need to be modified to work with cinderlib.

    We are validating known configuration options and ignoring unknown ones,
    like Cinder does.

    The NetApp driver was one of the drivers that would get broken, but
    since I have access to it and we can make a very small and targeted
    workaround to avoid breaking it, we do it as well.

    Closes-Bug: #1856556
    Change-Id: I67fbf8e9d7ee79f3d6617b4d0ae755dae0e1987a
    (cherry picked from commit fbd7a72c1bbfe4696eada41064c476ba3ecd6a8f)