10.2.

variant: openshift
version: 4.16.0
metadata:
  name: 40-worker-custom-journald
  labels:
    machineconfiguration.openshift.io/role: "worker"
storage:
  files:
  - path: /etc/systemd/journald.conf
    mode: 0644 1
    overwrite: true
    contents:
      inline: |
        Compress=yes 2
        ForwardToConsole=no 3
        ForwardToSyslog=no
        MaxRetentionSec=1month 4
        RateLimitBurst=10000 5
        RateLimitIntervalSec=30s
        Storage=persistent 6
        SyncIntervalSec=1s 7
        SystemMaxUse=8G 8
        SystemKeepFree=20% 9
        SystemMaxFileSize=10M 10

$ butane 40-worker-custom-journald.bu -o 40-worker-custom-journald.yaml

$ oc apply -f 40-worker-custom-journald.yaml

$ oc describe machineconfigpool/worker

Name:         worker
Namespace:
Labels:       machineconfiguration.openshift.io/mco-built-in=
Annotations:  <none>
API Version:  machineconfiguration.openshift.io/v1
Kind:         MachineConfigPool

...

Conditions:
  Message:
  Reason:                All nodes are updating to rendered-worker-913514517bcea7c93bd446f4830bc64e