The baremetal OCP clusters installed using Assisted Installer via ACM may end in a configuration which is a mix between IPI and UPI, where the KNI infra is installed (coredns, haproxy and keepalived pods), but actually the nodes are ignited more like it is UPI and are either associated to unmanaged baremetalhosts (master nodes) or not associated with any baremetalhost (worker nodes). (see additional info section)

Our understanding is that the hosts are going to be managed by ACM and the components of the BareMetal Operator are going to be installed with the cluster but actually not being used.
Since there is not an official way to achieve these results manually, our goal is to clarify the supportability of this solution, our opinion is that since this is a widely used and consolidated way of deploying the clusters, it should be considered as supported by Red Hat.

Our questions to engineering:
- can this installation type raise any supportability issues, especially on charge of the BareMetal Operator components?
- can the BareMetal Operator be safely deemed inactive in these kind of installations?

by installing a baremetal cluster using Assisted Installer via ACM.

Install a baremetal cluster using Assisted Installer via ACM

We had some discussions with both AI and metal engineering that we are reporting here for completeness:

Discussion thread in the #forum-ocp-assisted-installer:
https://redhat-internal.slack.com/archives/CUPJTHQ5P/p1690365152338019

Discussion thread in the #forum-ocp-metal-platform:
https://redhat-internal.slack.com/archives/CFP6ST0A3/p1690295392066059

-----------

Sample of resulting install-config: (oc get cm -n kube-system cluster-config-v1 -o yaml):
~~~
data:
  install-config: |
    apiVersion: v1
    baseDomain: ocp4.example.com
    compute:
    - architecture: amd64
      hyperthreading: Enabled
      name: worker
      platform: {}
      replicas: 0
    controlPlane:
      architecture: amd64
      hyperthreading: Enabled
      name: master
      platform: {}
      replicas: 3
    metadata:
      creationTimestamp: null
      name: ocp-app
    networking:
      clusterNetwork:
      - cidr: 1.2.0.0/16
        hostPrefix: 23
      machineNetwork:
      - cidr: 10.0.0.128/26
      networkType: OpenShiftSDN
      serviceNetwork:
      - 1.12.0.0/16
    platform:
      baremetal:
        apiVIP: 10.0.0.189
        externalBridge: baremetal
        hosts:
        - bmc:
            address: ""
            disableCertificateVerification: false
            password: ""
            username: ""
          bootMACAddress: 00:25:b5:aa:bb:cc
          bootMode: legacy
          hardwareProfile: unknown
          name: master-0.ocp4.example.com
          role: master
        - bmc:
            address: ""
            disableCertificateVerification: false
            password: ""
            username: ""
          bootMACAddress: 00:25:b5:aa:bb:cd
          bootMode: legacy
          hardwareProfile: unknown
          name: master-1.ocp4.example.com
          role: master
        - bmc:
            address: ""
            disableCertificateVerification: false
            password: ""
            username: ""
          bootMACAddress: 00:25:b5:aa:bb:ce
          bootMode: legacy
          hardwareProfile: unknown
          name: master-2.ocp4.example.com
          role: master
        ingressVIP: 10.0.0.190
        libvirtURI: qemu:///system
        provisioningNetwork: Disabled
        provisioningNetworkInterface: ""
    publish: External
    pullSecret: ""
~~~

Sample of bmh resources:
~~~
NAME                        STATUS       STATE       CONSUMER                 BMC   HARDWARE_PROFILE   ONLINE   ERROR   AGE
master-0.ocp4.example.com   discovered   unmanaged   ocp-app-zsmfk-master-0                            true             270d
master-1.ocp4.example.com   discovered   unmanaged   ocp-app-zsmfk-master-1                            true             270d
master-2.ocp4.example.com   discovered   unmanaged   ocp-app-zsmfk-master-2                            true             270d
~~~

Sample of machine resources:
~~~
NAME                     PHASE     TYPE   REGION   ZONE   AGE    NODE                        PROVIDERID                                                                                              STATE
ocp-app-zsmfk-master-0   Running                          270d   master-0.ocp4.example.com   baremetalhost:///openshift-machine-api/master-0.ocp4.example.com/b91c0424-7404-4d95-ae53-614167a86ded   unmanaged
ocp-app-zsmfk-master-1   Running                          270d   master-1.ocp4.example.com   baremetalhost:///openshift-machine-api/master-1.ocp4.example.com/f58cecd5-acc6-40f3-a08a-58ee14b95459   unmanaged
ocp-app-zsmfk-master-2   Running                          270d   master-2.ocp4.example.com   baremetalhost:///openshift-machine-api/master-2.ocp4.example.com/9aeae70a-456e-4ee4-96d8-454ffb9bff36   unmanaged
~~~