create from zero, works /var on master node

99_openshift-machineconfig_99-master-ssh.yaml

apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
metadata:
  labels:
    machineconfiguration.openshift.io/role: master
  name: 99-master-ssh
spec:
  config:
    ignition:
      version: 3.1.0
    storage:
      disks:
      - device: /dev/nvme0n1
        wipeTable: false
        partitions:
        - sizeMiB: 10240
          startMiB: 10240
          label: var
      filesystems:
        - path: /var
          device: /dev/disk/by-partlabel/var
          format: xfs
    systemd:
      units:
        - name: var.mount
          enabled: true
          contents: |
            [Unit]
            Before=local-fs.target
            [Mount]
            Where=/var
            What=/dev/disk/by-partlabel/var
            [Install]
            WantedBy=local-fs.target
  fips: false
  kernelArguments: null
  kernelType: ""
  osImageURL: ""

works:
sh-4.4# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
nvme0n1 259:0 0 120G 0 disk
|-nvme0n1p1 259:1 0 384M 0 part /boot
|-nvme0n1p2 259:2 0 127M 0 part /boot/efi
|-nvme0n1p3 259:3 0 1M 0 part
|-nvme0n1p4 259:4 0 9.5G 0 part
| '-coreos-luks-root-nocrypt 253:0 0 9.5G 0 dm /sysroot
'-nvme0n1p5 259:5 0 10G 0 part /var