nova/releasenotes/notes/fix-ironic-compute-restart-port-attachments-3282e9ea051561d4.yaml
Julia Kreger 7f81cf28bf Ignore plug_vifs on the ironic driver
When the nova-compute service starts, by default it attempts to
startup instance configuration states for aspects such as networking.
This is fine in most cases, and makes a lot of sense if the
nova-compute service is just managing virtual machines on a hypervisor.

This is done, one instance at a time.

However, when the compute driver is ironic, the networking is managed
as part of the physical machine lifecycle potentially all the way into
committed switch configurations. As such, there is no need to attempt
to call ``plug_vifs`` on every single instance managed by the
nova-compute process which is backed by Ironic.

Additionally, using ironic tends to manage far more physical machines
per nova-compute service instance then when when operating co-installed
with a hypervisor. Often this means a cluster of a thousand machines,
with three controllers, will see thousands of un-needed API calls upon
service start, which elongates the entire process and negatively
impacts operations.

In essence, nova.virt.ironic's plug_vifs call now does nothing,
and merely issues a debug LOG entry when called.

Closes-Bug: #1777608
Change-Id: Iba87cef50238c5b02ab313f2311b826081d5b4ab
2021-11-03 05:57:08 -07:00

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YAML

---
fixes:
- |
Fixes slow compute restart when using the ``nova.virt.ironic`` compute
driver where the driver was previously attempting to attach VIFS on
start-up via the ``plug_vifs`` driver method. This method has grown
otherwise unused since the introduction of the ``attach_interface``
method of attaching VIFs. As Ironic manages the attachment of VIFs to
baremetal nodes in order to align with the security requirements of a
physical baremetal node's lifecycle. The ironic driver now ignores calls
to the ``plug_vifs`` method.