Move OVN Metadata Agent code to the new OVN Neutron Agent

[Lucas Alvares Gomes]

A new agent called OVN Neutron Agent has been introduced in Neutron by https://bugs.launchpad.net/neutron/+bug/1998608.

This new agent introduced new capabilities such as QoS for hardware offloaded ports but, more importantly this agent was made pluggable by design because the community agreed that the "multiple agents" approach may not be ideal and so we are aiming to extend this new agent with new and existing capabilities and have it all in one place.

One of this capabilities is the OVN Metadata Agent that currently runs as a separated agent and should be refactored/ported to the new OVN Neutron Agent.

This LP is to reflect that work.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/c/openstack/neutron/+/898238

[OpenStack Infra (hudson-openstack)]

Change abandoned by "Slawek Kaplonski <email address hidden>" on branch: master
Review: https://review.opendev.org/c/openstack/neutron/+/898238
Reason: This review is > 4 weeks without comment, and failed Zuul jobs the last time it was checked. We are abandoning this for now. Feel free to reactivate the review by pressing the restore button and leaving a 'recheck' comment to get fresh test results.

[OpenStack Infra (hudson-openstack)]

Related fix proposed to branch: master
Review: https://review.opendev.org/c/openstack/neutron/+/903947

[OpenStack Infra (hudson-openstack)]

Related fix proposed to branch: master
Review: https://review.opendev.org/c/openstack/neutron/+/903977

[OpenStack Infra (hudson-openstack)]

Related fix proposed to branch: master
Review: https://review.opendev.org/c/openstack/neutron/+/905297

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/c/openstack/neutron/+/903947
Committed: https://opendev.org/openstack/neutron/commit/9e74ea11e8b6c06288f91c393b882e32a2524235
Submitter: "Zuul (22348)"
Branch: master

commit 9e74ea11e8b6c06288f91c393b882e32a2524235
Author: Rodolfo Alonso Hernandez <email address hidden>
Date: Tue Dec 19 11:15:06 2023 +0000

    [OVN] The OVN agent exposes the ``load_config`` method.

    Now the ``OVNNeutronAgent.load_config`` method is public and accessible
    by the OVN agent extensions.

    This patch also makes use of the property ``ovs_idl``, that implicitly
    loads the OVS IDL if it is not done previously.

    Related-Bug: #2017871
    Change-Id: I356c16d753b524736673a665a6590ae903be5682

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/c/openstack/neutron/+/903977
Committed: https://opendev.org/openstack/neutron/commit/cd1eb7852dad5a427c20aafcb0d2cf3d096daa58
Submitter: "Zuul (22348)"
Branch: master

commit cd1eb7852dad5a427c20aafcb0d2cf3d096daa58
Author: Rodolfo Alonso Hernandez <email address hidden>
Date: Tue Dec 19 12:30:38 2023 +0000

    [OVN] Add a start method to the OVN agent extensions

    Each OVN agent extension can implement a start method. It is called
    after the extension manager initialization, at the end of the
    ``OVNNeutronAgent.start`` call.

    Related-Bug: #2017871
    Change-Id: I334027f061fa963c1cf24540b27c1ff76145b977

[OpenStack Infra (hudson-openstack)]

Related fix proposed to branch: master
Review: https://review.opendev.org/c/openstack/neutron-tempest-plugin/+/909860

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/c/openstack/neutron/+/898238
Committed: https://opendev.org/openstack/neutron/commit/fe31f4fe029388ffd393d94bb0899ee8d5632bf9
Submitter: "Zuul (22348)"
Branch: master

commit fe31f4fe029388ffd393d94bb0899ee8d5632bf9
Author: Rodolfo Alonso Hernandez <email address hidden>
Date: Tue Dec 19 07:54:26 2023 +0000

    [OVN] Implement OVN agent metadata extension

    This patch is implementing the OVN agent metadata extension, by reusing
    the OVN metadata class. The class ``MetadataAgent`` is inherited in the
    ``MetadataExtension`` class. The goal is to use the same code in both
    implementations (until the OVN metadata agent is deprecated).

    The OVN agent metadata extension has a different initialization
    process. The OVN and OVS IDL connections are created during the
    extension initialization but are not accessible. The ``start`` method
    is used to load the configuration, execute the sync process and
    register the metadata extension.

    This extension will replace the need of the OVN metadata agent. The
    deprecation of this agent will imply the refactor of the existing code
    that now is shared between both agents.

    This new OVN agent will be tested in the "neutron-tempest-plugin-ovn"
    CI job, after the change done in the following patch.

    Needed-By: https://review.opendev.org/c/openstack/neutron-tempest-plugin/+/909860

    Partial-Bug: #2017871
    Change-Id: I4381a67648a9b6198a8d936db784964d74dc87a1

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/c/openstack/neutron-tempest-plugin/+/909860
Committed: https://opendev.org/openstack/neutron-tempest-plugin/commit/452802732908dedf5fe20c2c82f6d717af1b0f1e
Submitter: "Zuul (22348)"
Branch: master

commit 452802732908dedf5fe20c2c82f6d717af1b0f1e
Author: Rodolfo Alonso Hernandez <email address hidden>
Date: Thu Feb 22 12:21:06 2024 +0000

    [OVN] Use the OVN agent in "neutron-tempest-plugin-ovn"

    Now, only in master (Caracal 2024.1), the "neutron-tempest-plugin-ovn"
    job used the OVN agent with the metadata extension, instead of the
    OVN metadata agent. This functionality is implemented in the referred
    link.

    The OVN agent won't be used in stable releases.

    Depends-On: https://review.opendev.org/c/openstack/neutron/+/898238

    Related-Bug: #2017871
    Change-Id: I92b85ec1ac609ada18fc1185e56f07c36d353518

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/c/openstack/neutron/+/905297
Committed: https://opendev.org/openstack/neutron/commit/4275aebe68949dc276f98aa6630bfd82994997b7
Submitter: "Zuul (22348)"
Branch: master

commit 4275aebe68949dc276f98aa6630bfd82994997b7
Author: Rodolfo Alonso Hernandez <email address hidden>
Date: Fri Jan 19 15:09:42 2024 +0000

    [OVN] Add documentation about the OVN agent

    Related-Bug: #2017871
    Change-Id: Iba24a034edf03da0a6e8c03264d5d1134cf45e56