---------- Forwarded message ---------
From: Matt Riedemann <mriedemos@gmail.com>
Date: mar 27 nov 2018, 19:03
Subject: Re: [Openstack-operators] Nova hypervisor uuid
To: <openstack-operators@lists.openstack.org>

On 11/27/2018 11:32 AM, Ignazio Cassano wrote:
> Hi  All,
> Please anyone know where hypervisor uuid is retrived?
> Sometime updating kmv nodes with yum update it changes and in nova
> database 2 uuids are assigned to the same node.
> regards
> Ignazio
>
>
>
>
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>

To be clear, do you mean the computes_nodes.uuid column value in the
cell database? Which is also used for the GET /os-hypervisors response
'id' value if using microversion >= 2.53. If so, that is generated
randomly* when the compute_nodes table record is created:

https://github.com/openstack/nova/blob/8545ba2af7476e0884b5e7fb90965bef92d605bc/nova/compute/resource_tracker.py#L588

https://github.com/openstack/nova/blob/8545ba2af7476e0884b5e7fb90965bef92d605bc/nova/objects/compute_node.py#L312

When you hit this problem, are you sure the hostname on the compute host
is not changing? Because when nova-compute starts up, it should look for
the existing compute node record by host name and node name, which for
the libvirt driver should be the same. That lookup code is here:

https://github.com/openstack/nova/blob/8545ba2af7476e0884b5e7fb90965bef92d605bc/nova/compute/resource_tracker.py#L815

So the only way nova-compute should create a new compute_nodes table
record for the same host is if the host/node name changes during the
upgrade. Is the deleted value in the database the same (0) for both of
those records?

* The exception to this is for the ironic driver which re-uses the
ironic node uuid as of this change: https://review.openstack.org/#/c/571535/

--

Thanks,

Matt

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