QOS minimum bandwidth rejection of non-physnet network and updates should be driver specific

[Tom Stappaerts]

When adding a qos policy to a network or port, there is the following check in the qos_plugin:
            # minimum-bandwidth rule is only supported (independently of
            # drivers) on networks whose first segment is backed by a physnet
            if rule.rule_type == qos_consts.RULE_TYPE_MINIMUM_BANDWIDTH:
                net = network_object.Network.get_object(
                    context, id=port.network_id)
                physnet = net.segments[0].physical_network
                if physnet is None:
                    raise qos_exc.QosRuleNotSupported(rule_type=rule.rule_type,
                                                      port_id=port['id'])
To my knowledge this statement is simply untrue as it is precisly the reference drivers which have this problem, not necessarily all drivers. This blocks me from creating a qos_driver that does support mimimum bandwidth without a physnet.
The same goes for min_bw_rule_updates when the port is bound.

I propose we move those checks to the qos_drivers themselves.

[Rodolfo Alonso (rodolfo-alonso-hernandez)]

Hello:

Just to add a bit of context, this other bug [1] is related to this one. [1] introduced this limitation; the physnet is the source of BW and that's how the min-BW can be guaranteed, by knowing the amount of BW avaiable.

Regards.

[1] https://bugs.launchpad.net/neutron/+bug/1819029

[Slawek Kaplonski (slaweq)]

We discussed about this on today's drivers meeting: http://eavesdrop.openstack.org/meetings/neutron_drivers/2020/neutron_drivers.2020-01-31-14.00.log.html#l-43

Here is brief summary of our discussion:
- issue mentioned in this LP should be treated as regular bug - we simply did validation if network is phys_net in wrong place. Instead of doing it in qos_plugin: https://github.com/openstack/neutron/blob/master/neutron/services/qos/qos_plugin.py#L229 we should move it to the driver.is_rule_supported() method: https://opendev.org/openstack/neutron-lib/src/branch/master/neutron_lib/services/qos/base.py#L71

- after this will be fixed, if You want to use min bw rules without phys_nets, there will be problem with reporting available bw to the placement. We should think about how to report bandwidth in such case and that should be new RFE.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/705694

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/705695

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/705694
Committed: https://git.openstack.org/cgit/openstack/neutron-lib/commit/?id=6f3fb7fc8199b8c374e6e97a2e5a617a47b30671
Submitter: Zuul
Branch: master

commit 6f3fb7fc8199b8c374e6e97a2e5a617a47b30671
Author: Bence Romsics <email address hidden>
Date: Tue Feb 4 14:02:22 2020 +0100

    Extend qos DriverBase with validate_rule_for_port()

    The openvswitch qos driver supports the min-bw qos rule only on
    networks backed by physnets. Currently the qos driver interface does
    not have a method that takes both the policy/rule and the network/port,
    therefore we don't have enough information in the driver to tell if
    we support the min-bw rule for a port or not. This change introduces
    validate_rule_for_port(..., rule, port) so we have all the information
    to tell.

    The base method validate_rule_for_port() is concrete and returns True
    for backwards compatibility.

    Change-Id: I58a47bb895bede219cfeebbf0665aaf01660ce89
    Needed-By: https://review.opendev.org/705695
    Partial-Bug: #1861442
    Related-Bug: #1819029

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/705695
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=321afc8f897c8132ddc6edd2b59285111d0d73e0
Submitter: Zuul
Branch: master

commit 321afc8f897c8132ddc6edd2b59285111d0d73e0
Author: Bence Romsics <email address hidden>
Date: Tue Feb 4 14:02:30 2020 +0100

    Move rejection of min-bw rule on non-physnet port to the ovs qos driver

    The ovs qos driver only supports the min-bw rule on physnet ports.
    However other (future) qos drivers may support the min-bw rule on
    non-physnet ports too, therefore implementing the rejection of the
    unsupported combination in the qos plugin was a bug.

    This change moves the rejection from the qos plugin to the ovs qos
    driver.

    Change-Id: I02d77a03c411dc8ab303a7d7b53d7ea93cc9f4c6
    Closes-Bug: #1861442
    Depends-On: https://review.opendev.org/705694
    Related-Bug: #1819029

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/train
Review: https://review.opendev.org/c/openstack/neutron/+/787492

[Slawek Kaplonski (slaweq)]

This bug has had a related patch abandoned and has been automatically un-assigned due to inactivity. Please re-assign yourself if you are continuing work or adjust the state as appropriate if it is no longer valid.

[OpenStack Infra (hudson-openstack)]

Change abandoned by "Slawek Kaplonski <email address hidden>" on branch: stable/train
Review: https://review.opendev.org/c/openstack/neutron/+/787492
Reason: This review is > 4 weeks without comment and currently blocked by a core reviewer with a -2. We are abandoning this for now. Feel free to reactivate the review by pressing the restore button and contacting the reviewer with the -2 on this review to ensure you address their concerns.