failed rescue should not error an instance

[Matthew Sherborne]

Currently if one attempts to put a VM into rescue mode and the operation fails. The VM is set to vm_state.ERROR.

As a customer/end user, if I attempt to put my VM in rescue mode and it fails, I would like it to stay in ACTIVE mode so that I can pursue other repair options, such as reboot or migrate.

If it's in ERROR status, only someone with admin api access can get it out again. For me (the end user) that means more down time while I find an admin to help me.

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If a rescue attempt fails, the VM's state should return to what it was before the rescue attempt started, and the user should be notified of the failure.

[Matthew Sherborne (msherborne+openstack)]

This undoes half of https://bugs.launchpad.net/nova/+bug/919444

In that bug, they say, if we fail to UNrescue an instance, it should be put into error state.

However the implementation also puts it into error state if a rescue attempt fails.

If a rescue attempt fails, it should revert the instance back to it's original state.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/27198

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/27198
Committed: http://github.com/openstack/nova/commit/40692574bbdefbdfa4a6f3366bec524fd4612400
Submitter: Jenkins
Branch: master

commit 40692574bbdefbdfa4a6f3366bec524fd4612400
Author: Matthew Sherborne <email address hidden>
Date: Sat Apr 20 19:08:07 2013 +1000

    If rescue fails don't error the instance

    If a rescue attempt fails, the VM's state should return to what it was
    before the rescue attempt started, and the user should be notified of
    the failure.

    Fixes bug: 1170328

    Change-Id: If5e97d06a3617adad83a4bba2ac6320616bbe83b