[OVN] OVN metadata agent check to restart the HAProxy container

[Rodolfo Alonso]

Since [1], we restart the HAProxy process of each network (datapath) in order to "honor any potential changes in their configuration." [2].

This process could slow down the OVN Metadata agent restart and could potentially interfere with a VM boot-up if the HAProxy process is restarted in the middle.

This bug proposes an optimization that checks the IPv6 support of the HAProxy running process to decide to restart it or not.

[1]https://github.com/openstack/neutron/commit/d9c8731af36d4eb53d9266733fec24659f2dc5a8
[2]https://github.com/openstack/neutron/commit/d9c8731af36d4eb53d9266733fec24659f2dc5a8#diff-95903c989a1d043a90abe006cedd7ec20bd7a36855c3219cd74580cfa125c82fR349-R351

[Ihar Hrachyshka (ihar-hrachyshka)]

@Rodolfo I wonder why this is Low. Isn't it a 1) regression and 2) has impact on datapath? I would consider it more important then, unless we know the actual impact is minuscule. Is it the case here?

[Rodolfo Alonso (rodolfo-alonso-hernandez)]

Hello Ihar:

This issue is a side effect of an issue found during the Tobiko tests [1] in OSP17/Wallaby (with some additional backported features: OVN IPv6 metadata); this issue is still present in master.

This is not a regression because it is needed to restart the HAProxy containers to update the configuration. However, it could have some kind of impact if a VM is just retrieving the metadata in this very moment. Despite this restart, that is usually fast, the cloud-init process try to retrieve several times the metadata thus the HAProxy restart should not affect.

In any case, in an environment that has been already upgraded to a OVN Metadata agent with IPv6 support (and the pre existing HAProxy processes have been restarted) there is no need to restart them again. This is the improvement proposed in this LP bug.

Regards.

[1]https://bugzilla.redhat.com/show_bug.cgi?id=2310111

[Rodolfo Alonso (rodolfo-alonso-hernandez)]

Raising the importance to medium.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/c/openstack/neutron/+/929604

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/2024.2
Review: https://review.opendev.org/c/openstack/neutron/+/931790

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/2024.1
Review: https://review.opendev.org/c/openstack/neutron/+/931791

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/c/openstack/neutron/+/929604
Committed: https://opendev.org/openstack/neutron/commit/7b7f8d986a4f818d289149c6960c9eb8b62b432d
Submitter: "Zuul (22348)"
Branch: master

commit 7b7f8d986a4f818d289149c6960c9eb8b62b432d
Author: Rodolfo Alonso Hernandez <email address hidden>
Date: Sat Sep 14 16:17:18 2024 +0000

    [OVN] Check metadata HA proxy configuration before restart

    Since [1], the OVN Metadata agent has support for IPv6. If the agent
    is updated, the HA proxy instances need to be reconfigured and
    restarted. However, that needs to be done only once; the next time
    the OVN agent is restarted, if the HA proxy instances are updated
    (have IPv6 support), they won't be restarted.

    [1]https://review.opendev.org/c/openstack/neutron/+/894026

    Closes-Bug: #2079996
    Change-Id: Id0f678c7ffe162df42e18dfebb97dce677fc79fc

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/c/openstack/neutron/+/931790
Committed: https://opendev.org/openstack/neutron/commit/a7ff04edea6db2dccc608243ea3a59c3e0257da0
Submitter: "Zuul (22348)"
Branch: stable/2024.2

commit a7ff04edea6db2dccc608243ea3a59c3e0257da0
Author: Rodolfo Alonso Hernandez <email address hidden>
Date: Sat Sep 14 16:17:18 2024 +0000

    [OVN] Check metadata HA proxy configuration before restart

    Since [1], the OVN Metadata agent has support for IPv6. If the agent
    is updated, the HA proxy instances need to be reconfigured and
    restarted. However, that needs to be done only once; the next time
    the OVN agent is restarted, if the HA proxy instances are updated
    (have IPv6 support), they won't be restarted.

    [1]https://review.opendev.org/c/openstack/neutron/+/894026

    Closes-Bug: #2079996
    Change-Id: Id0f678c7ffe162df42e18dfebb97dce677fc79fc
    (cherry picked from commit 7b7f8d986a4f818d289149c6960c9eb8b62b432d)

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/c/openstack/neutron/+/931791
Committed: https://opendev.org/openstack/neutron/commit/72fe3e19866b19958fdf4f438dbefb9553b2ac93
Submitter: "Zuul (22348)"
Branch: stable/2024.1

commit 72fe3e19866b19958fdf4f438dbefb9553b2ac93
Author: Rodolfo Alonso Hernandez <email address hidden>
Date: Sat Sep 14 16:17:18 2024 +0000

    [OVN] Check metadata HA proxy configuration before restart

    Since [1], the OVN Metadata agent has support for IPv6. If the agent
    is updated, the HA proxy instances need to be reconfigured and
    restarted. However, that needs to be done only once; the next time
    the OVN agent is restarted, if the HA proxy instances are updated
    (have IPv6 support), they won't be restarted.

    [1]https://review.opendev.org/c/openstack/neutron/+/894026

    Conflicts:
        neutron/agent/linux/utils.py
        neutron/tests/unit/agent/dhcp/test_agent.py

    Closes-Bug: #2079996
    Change-Id: Id0f678c7ffe162df42e18dfebb97dce677fc79fc
    (cherry picked from commit 7b7f8d986a4f818d289149c6960c9eb8b62b432d)

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/neutron 26.0.0.0b1 development milestone.

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/neutron 25.1.0 Dalmatian release.

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/neutron 24.1.0 Caracal release.