Customer has successfully transitioned from OpenShift 4.11 UPI custom provisioning automation to OpenShift 4.14 ACM/Hive IPI-driven installations. This transition has highlighted several challenges and solutions, particularly concerning the use of a DHCP VM for IP address management.Currently customer is consuming 4.14 vSphere StaticIP Tech Preview with reference implementation of ipam-controller devised by one the RH Engineers.
 
they has moved out from 4.11 UPI custom provisioning automation into 4.14 ACM/Hive IPI driven installations. In the beggining it required usage of external DHCP VM.
 
DHCP VM usage came with below pains:
 
1. cost of lifecycle management of DHCP VM Operating System.
2. security concerns coming from Internal Security department of having DHCP server.
3. operational automation needs coming from removing stale infinite leases after VM removal.
 
That triggered Customer to explore other options and they have identified this Red Hat driven not directly supported solution https://github.com/openshift-splat-team/machine-ipam-controller created as reference implementation of GO controller for IPAM management inside the Kubernetes that could be used with vSphere StaticIP Tech preview. It would give Customer best of both worlds, as there was no need for DHCP, but cluster autoscaling capabilities through machinesets were preserved.  Customer also wanted to preserve IPAM IP allocation mechanism inside the cluster without delegating this authority outside as this creates dependency on other Customer teams.
 
That solution was used with great success inside Customer environments up to PROD environments. Customer is aware of the risk of ipam controller not being supported and staticIP being Tech Preview which is not recommended/supported to run in PROD.
 
Based on above success story and to circumvent highlighted risks Customer would like to request an RFE from Red Hat for onboarding and supporting that particular codebase https://github.com/openshift-splat-team/machine-ipam-controller and machine-ipam-controller image https://quay.io/repository/ocp-splat/machine-ipam-controller.
 
Current staticIP(4.14) solution for vSphere IPI provided by Red Hat only provides limited autoscaling capability of UPI cluster(requires custom automation that Customer wants to avoid building by move to IPI) without ability to use MachineSets out of the box.