Error Reasons being dropped in generic handler of _migrate_live

[moorryan]

The reason detail of the Errors: MigrationPreCheckError, NoValidHost, InvalidSharedStorage and InvalidLocalStorage are being dropped by the generic error handler of the _migrate_live function in nova/api/openstack/compute/contrib/admin_actions.py

The class exceptions of MigrationPreCheckError, NoValidHost, InvalidSharedStorage and InvalidLocalStorage are defined as:
class MigrationPreCheckError(MigrationError):
    msg_fmt = _("Migration pre-check error") + ": %(reason)s"
class NoValidHost(NovaException):
    msg_fmt = _("No valid host was found. %(reason)s")
class InvalidSharedStorage(NovaException):
    msg_fmt = _("%(path)s is not on shared storage: %(reason)s")
class InvalidLocalStorage(NovaException):
    msg_fmt = _("%(path)s is not on local storage: %(reason)s")

When errors are raised they are raised with a formatted reason message:
e.g. 'Unable to migrate %(instance_uuid)s: '
                        'Disk of instance is too large(available'
                        ' on destination host:%(available)s '
                        '< need:%(necessary)s)').....

The generic Exception handler in _migrate_live does not include the reason in the error raised - so the detail does not get back up to the client
except Exception:
            if host is None:
                msg = _("Live migration of instance %s to another host "
                        "failed") % id
            else:
                msg = _("Live migration of instance %(id)s to host %(host)s "
                        "failed") % {'id': id, 'host': host}
            LOG.exception(msg)
            # Return messages from scheduler
            raise exc.HTTPBadRequest(explanation=msg)

[moorryan (moorryan)]

see: https://review.openstack.org/#/c/56049/2

Change-Id: I3d7e0626223f2606c5e7205e5022e26585506cfb

[moorryan (moorryan)]

see: https://review.openstack.org/#/c/56049/ - has four +1 and a tick (core reviewer) - just waiting for approval

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/56049
Committed: http://github.com/openstack/nova/commit/7c0cfd9c9974d029da9c389efa79f7105eb6c0a6
Submitter: Jenkins
Branch: master

commit 7c0cfd9c9974d029da9c389efa79f7105eb6c0a6
Author: Ryan Moore <email address hidden>
Date: Tue Nov 12 15:52:18 2013 +0000

    handle migration errors

    handle errors:
       MigrationPreCheckError, NoValidHost,
       InvalidSharedStorage and InvalidLocalStorage
    in _migrate_live so that the 'reason' is passed up

    Closes-Bug: 1250523

    Change-Id: I3d7e0626223f2606c5e7205e5022e26585506cfb