There is no way to delete a cell mapping except via DB directly

[Matt Riedemann]

We currently provide a few ways to create cell mappings for cells v2 in nova-manage but we don't have a way to delete a cell mapping in case there are some created erroneously.

We should provide a nova-manage cell_v2 delete_cell command which allows deleting an empty cell mapping, it would take a cell uuid argument. If the cell is not found by uuid we should return an error. If the cell has mapped hosts or instances then it's not empty and we should return an error.

Later iterations of the command might allow a --force option to delete the host/instance mappings so that those could be moved to another cell, but that would require some more thought.

[OpenStack Infra (hudson-openstack)]

Related fix proposed to branch: master
Review: https://review.openstack.org/420449

[OpenStack Infra (hudson-openstack)]

Related fix proposed to branch: master
Review: https://review.openstack.org/420450

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/420451

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/420449
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=8677aca6542f7cf45ca1b3673dede84d264192aa
Submitter: Jenkins
Branch: master

commit 8677aca6542f7cf45ca1b3673dede84d264192aa
Author: Matt Riedemann <email address hidden>
Date: Sun Jan 15 15:28:01 2017 -0500

    Create HostMappingList object

    This creates the HostMappingList object which will provide
    a way to list HostMappings by a given CellMapping.id. This
    is going to be used later in a "nova-manage cell_v2 delete_cell"
    command.

    Change-Id: I58e0c5565013d8ef9753a9566841e83573a85afd
    Related-Bug: #1656691

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/420450
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=90cd8acf9112df2ce14d9d059d221bb38e7d6097
Submitter: Jenkins
Branch: master

commit 90cd8acf9112df2ce14d9d059d221bb38e7d6097
Author: Matt Riedemann <email address hidden>
Date: Sun Jan 15 15:55:15 2017 -0500

    Add InstanceMappingList.get_by_cell_id

    This adds the InstanceMappingList.get_by_cell_id method which will
    provide a way to list InstanceMappings by a given CellMapping.id. This
    is going to be used later in a "nova-manage cell_v2 delete_cell"
    command.

    Change-Id: I98a22161b28f2de32760c578713be27766e6809e
    Related-Bug: #1656691

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/420451
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=3e04a32df4d06f79a11423c9c0a7780d065187b1
Submitter: Jenkins
Branch: master

commit 3e04a32df4d06f79a11423c9c0a7780d065187b1
Author: Matt Riedemann <email address hidden>
Date: Sun Jan 15 16:29:33 2017 -0500

    Add nova-manage cell_v2 delete_cell command

    This provides a way to delete empty cell mappings which
    otherwise would have to be done directly in the database.

    Change-Id: I541b072638b5d50985145391e76f610417fdcaa6
    Closes-Bug: #1656691

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/nova 15.0.0.0b3 development milestone.