Unable to Deauthorize Hypervisor (Instances Still Exist)

Problem

• When attempting to disable a host, you receive an error similar to the following.

An unexpected error occurred trying to deauthorize host.

• Instances in the Clarity UI which reside on the hypervisor in question at Infrastructure > Instances are not in a standard state such as "Error," "Deleting" or "Active - Rebooting".
• The same instances do not respond to delete commands from the Clarity UI, OpenStack CLI, nor OpenStack API.

Environment

• Platform9 Managed OpenStack - All Versions
• Nova

Cause

A host with the hypervisor role cannot be removed from the OpenStack cluster when it is still hosting instances, in any state.

Resolution

1. Identify any remaining instances hosted on the hypervisor in question.

$ openstack server list --all-projects --host [host_uuid]

2. Issue the following commands to delete the remaining instances.

# nova reset-state [instance_uuid] --active# openstack server delete [instance_uuid]

3. Bring down the nova-compute service.

# nova service-force-down [host_uuid] nova-compute+--------------------------------------+--------------+-------------+| Host                                | Binary      | Forced down |+--------------------------------------+--------------+-------------+| [host_uuid]                         | nova-compute | True        |+--------------------------------------+--------------+-------------+

4. Verify the compute service has been brought down successfully.

$ nova service-list | grep [host_uuid]| 123 | nova-compute    | [host_uuid]        | nova    | enabled  | down  | 2018-10-02T19:05:47.000000 | -                                  |

5. At this point, you can complete the standard procedure for deauthorizing a host as described in How To Deauthorize A Host.