(feature) Shared IPAM IPRanges for both vips and vm ips

[lknite]

Describe the solution you'd like

When managing a workload cluster via cluster-api automate the assignment of the vip and vm ips.

On a namespace level:

• one or more InClusterIPPool resources
• label applied to InClusterIPPool resources: 'cluster-api-vips: true'
• label applied to InClusterIPPool resources: 'cluster-api-vm-ips: true'
• both labels may be applied to an InClusterIPPool resource

On a global level:

• one or more GlobalInClusterIPPool resources
• label applied to GlobalInClusterIPPool resources: 'cluster-api-vips: true'
• label applied to GlobalInClusterIPPool resources: 'cluster-api-vm-ips: true'
• both labels may be applied to a GlobalInClusterIPPool resource

Workflow

• If namespaced InClusterIPPool resources are available in the ns where the cluster is deployed, use those to allocate vip and vm ips, based on labels.
• If namespaced InClusterIPPool resources are available in the ns where the cluster is deployed, but are exhausted, fail with event out-of-vips, out-of-vm-ips, or out-of-vips-and-vm-ips
• If no namespaced InClusterIPPool resources exist, use GlobalInClusterIPPool resources if available

Additional labels

• Because more than one provider may be in use, and it may be desirable for all providers to use the same InClusterIPPools and/or GlobalInClusterIPPools, this can be enabled by applying the label 'cluster-api-allow-all-providers: true'
• If someone wishes to use GlobalInClusterIPPool resources, if the namespaced InClusterIPPools resources are exhausted, this may be enabled by adding a label 'cluster-api-allow-overflow-vips: true' and/or 'cluster-api-allow-overflow-vm-ips: true'

Anything else you would like to add:

• Allocating a vip is something that should be automated, in the same way that allocating a vm ip should be automated.
• Would allow for VIP_IP_RANGES in the ~/.cluster-api/clusterctl.conf in addition to NODE_IP_RANGES.
• Because labels are being used, this new feature would not break any existing implementations.

[chrischdi]

Note: one example implementation but not using the IPAM provider, but AVI/AKO/NSX instead (note I never tried it):

https://github.com/vmware-tanzu/load-balancer-operator-for-kubernetes/

I think this kind of problem qualifies to be a project independent of CAPV. Coupling with the IPAM provider may be a good thing because it would use standardised resources already, however I think lot's of use-cases may need to work together with proprietary IPAM systems and directly integrating them may be more feasible (e.g. Infoblox).