Goal

Allow hot plug of bridged network interfaces for VMs.

User Stories

• As a developer,
  I expect hotplug being available in CNV platform,
  since it is an industry standard I was using in the previous platform.

Non-Requirements

• <List of things not included in this epic, to alleviate any doubt raised during the grooming process.>
• This epic is not concerned with SR-IOV NIC hotplug, SR-IOV is tracked here: https://issues.redhat.com/browse/CNV-25461
• Hot-unplug is not needed
• In-place hot-plug is not a must, live-migration based hot-plug is also acceptable

Notes

• VM interface hot-plug should also be supported on cluster with multus version 3.
• Storage already supports hot-plug, we should learn from them.
• Support of hot-plug is being considered for CNI 2.0.
• Multus RFE: https://github.com/k8snetworkplumbingwg/multus-cni/issues/585
• One option to handle scheduling would be to a) If the needed resource is available, just plug it in b) if it is not, fail or migrate
• We could use RHV test-plan as a reference
• Epic https://issues.redhat.com/browse/CNV-21833 and specifically PR https://github.com/kubevirt/kubevirt/pull/6852 adding support to in-place hotplug, but only in case the cluster has multus version 4 or above.
• The interfaces will first appear on the VMI spec and the VM spec if the request contains `--persist`. Only after migration the VM, the interfaces will appear in the virt-launcher pod and the guest.

Design outline

https://docs.google.com/document/d/1oEuw0UIQFYHTVPRcS6a-QtDdWW2yeyOAWmlg5C1eWyU/edit

Done Checklist