Multi-homed nodes

[vxav]

Is your feature request related to a problem? Please describe.

The current implementation of CAPVCD allows to use only one network.
A customer has multiple networks for external access, internal infra traffic, internal workload traffic...
They have a hard requirement for the nodes to be attached to several networks.

Describe the solution you'd like

We need to be able to attach the node to several networks like in CAPO: https://github.com/kubernetes-sigs/cluster-api-provider-openstack/blob/main/docs/book/src/clusteropenstack/configuration.md#multiple-networks

Describe alternatives you've considered

No response

Additional context

No response

[erkanerol]

What do we want to do?

As stated above, We want to be able to attach multiple NICs to cluster nodes so that we can access multiple networks.

Current Implementation

• OvdcNetwork is a part of VCDClusterSpec.
  

  cluster-api-provider-cloud-director/api/v1beta1/vcdcluster_types.go

  Line 80 in 0f367c7

  OvdcNetwork string `json:"ovdcNetwork"`

• It is used while creating the vApp
  

  cluster-api-provider-cloud-director/controllers/vcdcluster_controller.go

  Line 782 in 0f367c7

  clusterVApp, err := vdcManager.GetOrCreateVApp(vcdCluster.Name, vcdCluster.Spec.OvdcNetwork)

  https://github.com/vmware/cloud-provider-for-cloud-director/blob/81b03e668ec1a5b5b552becf3d673e9aa7bb1f59/pkg/vcdsdk/vapp.go#L246

• Then the first network of vApp is attached to nodes.
  https://github.com/vmware/cloud-provider-for-cloud-director/blob/187fe988658117ac694999b4092307f1206bd16f/pkg/vcdsdk/vapp.go#L644

Shortly, current assumption is 1 cluster = 1 vApp = 1 OvdcNetwork

Other providers

I checked other providers (e.g. CAPO, CAPA) and saw that they mostly have a single parameter in Cluster level but they allow users to state more network interfaces per Machine.

CAPA

• https://github.com/kubernetes-sigs/cluster-api-provider-aws/blob/main/api/v1beta1/awscluster_types.go#L37
• https://github.com/kubernetes-sigs/cluster-api-provider-aws/blob/main/api/v1beta1/awsmachine_types.go#L134

CAPO

• https://github.com/kubernetes-sigs/cluster-api-provider-openstack/blob/main/api/v1alpha6/openstackcluster_types.go#L43
• https://github.com/kubernetes-sigs/cluster-api-provider-openstack/blob/main/api/v1alpha6/openstackmachine_types.go#L60

Proposal

• Adding a new string array (OvdcNetworks) in VCDMachine spec to allow users to state network interfaces per machine.
• When it is empty, OvdcNetwork in Cluster spec can be used by default.
• machine_controller also has to ensure that that network is added to vApp too.

[erkanerol]

Here is the draft PR for this proposal #254