OpenStack VMs cannot be created with 'direct' vNIC type

[Brian Holmes]

Juju's OpenStack provider is only able to create Neutron ports based on a network ID and subnet ID [1]. To support the use of SR-IOV with charms such as kubernetes-worker, the provider needs to be capable of also setting a 'vnic-type' of 'direct' (or 'direct-physical', or 'macvtap') rather than always using the default of 'normal' [2].

We've considered the potential workaround of allowing Juju to initially provision VMs with only 'normal' ports attached, then going back and manually adding the 'direct' ports later. However, OpenStack only supports attaching SR-IOV ports to existing VMs from the Victoria release onward [3] and our OpenStack clouds all run the slightly older Ussuri LTS release.

[1] https://github.com/juju/juju/blob/main/provider/openstack/networking.go#L237
[2] https://docs.openstack.org/neutron/latest/admin/config-sriov.html#launching-instances-with-sr-iov-ports
[3] https://docs.openstack.org/neutron/latest/admin/config-sriov.html#known-limitations

[Joseph Phillips (manadart)]

We'll discuss this as a potential item for our next roadmap.