invalid value for enabled_drivers does not prevent conductor from starting

[aeva black]

The ironic-conductor service will start even if the [conductor] "enabled_drivers" configuration option specifies non-existent drivers. It should raise an error and stop when misconfigured, rather than silently running.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/152844

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/152844
Committed: https://git.openstack.org/cgit/openstack/ironic/commit/?id=a53a00303054bcb40ca92722d6125fd5d0b4845a
Submitter: Jenkins
Branch: master

commit a53a00303054bcb40ca92722d6125fd5d0b4845a
Author: Devananda van der Veen <email address hidden>
Date: Mon Feb 2 01:18:26 2015 -0800

    Conductor errors if enabled_drivers are not found

    The conductor service should fail during startup if a configured driver,
    eg. one that is specified in "enabled_drivers", is not found. At the
    moment, it merely ignores missing drivers.

    In addition to adding a check that all configured drivers are loaded,
    this patch re-arranges some of the initialization of ConductorManager
    such that an exception during init_host() does not result in
    secondary exceptions being logged and obfuscating the cause, namely,
    that no drivers were loaded.

    Closes-bug: #1417954

    Change-Id: I6a96f4b49891c92859479656fe36d2bbd38fe602