[RFE]Adopt oslo-config-generator

[Tan Lin]

Currently ironic use generate_sample.sh to create opts. It will call ironic.common.config_generator.generator which is copied from oslo_incubation long time ago.
Oslo.conf provide a module named oslo-config-generator to do this job. It is better to make use of it like other projects.
http://docs.openstack.org/developer/oslo.config/generator.html
https://blueprints.launchpad.net/nova/+spec/oslo-config-generator

Here is one example about how the config looks like:
https://github.com/openstack/cinder/blob/master/cinder/config/cinder-config-generator.conf

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/247331
Committed: https://git.openstack.org/cgit/openstack/ironic/commit/?id=773aa20a4ac0364a2219877863017224c7f1089f
Submitter: Jenkins
Branch: master

commit 773aa20a4ac0364a2219877863017224c7f1089f
Author: Lin Tan <email address hidden>
Date: Thu Nov 19 14:50:38 2015 +0800

    Make use of oslo-config-generator

    oslo_config provide a utility for generating sample config files,
    which provide more detail about opts, like Minimum/Maximum value
    and Allowed values.
    So drop Ironic's "generate_sample.sh" which was copied from
    oslo-incubator long time ago.

    Add a new entry point "ironic" under oslo.config.opts namespace to
    explore config options to oslo-config-generator.

    After this patch, new config options of Ironic code should register
    with ironic/conf/opts.py. New external libraries should
    register with tools/config/ironic-config-generator.conf

    There is a bug #1554657 with oslo-config about deprecated_group.
    This bug have impact of some configs from keystonemiddleware
    and oslo.messaging in ironic.conf.sample
    So currently, deprecated option should always add the deprecated_group
    even it didn't alter the group, otherwise the deprecated group value will
    be 'DEFAULT'.

    Update etc/ironic/ironic.conf.sample via running 'tox -egenconfig'.

    Closes-Bug: #1564195
    Change-Id: If7721e98e69b6f54f1ee04a07477396b86583371

[Thierry Carrez (ttx)]

This issue was fixed in the openstack/ironic 6.0.0 release.