Summary:
Enhancement to the current networking capabilities to allow administrators and users to declaratively assign a specific, static IP address to a Virtual Machine (VM) or a pod from the subnet of an attached User-Defined Network (UDN) or Cluster-User-Defined Network (CUDN). This functionality is crucial for applications with dependencies on well-known, stable IP addresses and for facilitating seamless integration with external systems.

This RFE addresses the need for a native, declarative method to assign a specific IP address to a VM or pod directly within its definition, leveraging the IP address space of the UDN/CUDN it is connected to.

Suggestion:
**

For a VirtualMachine resource, a new ipAddress field could be added under the interfaces section of the VM's network definition.

Example:

apiVersion: kubevirt.io/v1
kind: VirtualMachine
metadata:
  name: my-vm
spec:
  template:
    spec:
      domain:
        devices:
          interfaces:
            - name: default
              masquerade: {}
            - name: udn-network
              bridge: {}
              ipAddress: "192.168.1.100" # Proposed new field
      networks:
        - name: default
          pod: {}
        - name: udn-network
          multus:
            networkName: my-udn

Use Cases

• Legacy Applications: Migration of traditional applications that are hard-coded to communicate with specific IP addresses.
• Database Clustering: High-availability database clusters often require static IP addresses for member discovery and client connections.
• External System Integration: Systems outside the cluster, such as firewalls, monitoring tools, and DNS servers, can be configured with stable IP addresses for the in-cluster workloads.
• External IPAM management: Customers often use external IPAM systems (eg, Infoblox). By having the ability to set a static IP, customers can integrate OpenShift Virt and the IPAM system via automation (for example, an Ansible playbook that reserves or obtains an IP from Infoblox and then deploys a new VM using that IP).
• Regulatory and Security Compliance: Certain security postures and auditing requirements are simplified when critical services have fixed and auditable IP addresses.