Configuring a shared container partition for the image-based upgrade - Image-based upgrade for single-node OpenShift clusters | Edge computing

Configuring a shared container partition between ostree stateroots
Configuring a shared container directory between ostree stateroots when using GitOps ZTP

Your single-node OpenShift clusters need to have a shared /var/lib/containers partition for the image-based upgrade. You can do this at install time.

Configuring a shared container partition between ostree stateroots

Apply a MachineConfig to both the seed and the target clusters during installation time to create a separate partition and share the /var/lib/containers partition between the two ostree stateroots that will be used during the upgrade process.

You must complete this procedure at installation time.

Procedure

Apply a MachineConfig to create a separate partition:

apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
metadata:
  labels:
    machineconfiguration.openshift.io/role: master
  name: 98-var-lib-containers-partitioned
spec:
  config:
    ignition:
      version: 3.2.0
    storage:
      disks:
        - device: /dev/disk/by-path/pci-<root_disk> (1)
          partitions:
            - label: var-lib-containers
              startMiB: <start_of_partition> (2)
              sizeMiB: <partition_size> (3)
      filesystems:
        - device: /dev/disk/by-partlabel/var-lib-containers
          format: xfs
          mountOptions:
            - defaults
            - prjquota
          path: /var/lib/containers
          wipeFilesystem: true
    systemd:
      units:
        - contents: |-
            # Generated by Butane
            [Unit]
            Before=local-fs.target
            Requires=systemd-fsck@dev-disk-by\x2dpartlabel-var\x2dlib\x2dcontainers.service
            After=systemd-fsck@dev-disk-by\x2dpartlabel-var\x2dlib\x2dcontainers.service

            [Mount]
            Where=/var/lib/containers
            What=/dev/disk/by-partlabel/var-lib-containers
            Type=xfs
            Options=defaults,prjquota

            [Install]
            RequiredBy=local-fs.target
          enabled: true
          name: var-lib-containers.mount

1	Specify the root disk.
2	Specify the start of the partition in MiB. If the value is too small, the installation will fail.
3	Specify a minimum size for the partition of 500 GB to ensure adequate disk space for precached images. If the value is too small, the deployments after installation will fail.

Configuring a shared container directory between ostree stateroots when using GitOps ZTP

When you are using the GitOps Zero Touch Provisioning (ZTP) workflow, you do the following procedure to create a separate disk partition on both the seed and target cluster and to share the /var/lib/containers partition.

You must complete this procedure at installation time.

Prerequisites

Install Butane. For more information, see "Installing Butane".

Procedure

Create the storage.bu file:

variant: fcos
version: 1.3.0
storage:
  disks:
  - device: /dev/disk/by-path/pci-<root_disk> (1)
    wipe_table: false
    partitions:
    - label: var-lib-containers
      start_mib: <start_of_partition> (2)
      size_mib: <partition_size> (3)
  filesystems:
    - path: /var/lib/containers
      device: /dev/disk/by-partlabel/var-lib-containers
      format: xfs
      wipe_filesystem: true
      with_mount_unit: true
      mount_options:
        - defaults
        - prjquota

1	Specify the root disk.
2	Specify the start of the partition in MiB. If the value is too small, the installation will fail.
3	Specify a minimum size for the partition of 500 GB to ensure adequate disk space for precached images. If the value is too small, the deployments after installation will fail.

Convert the storage.bu to an Ignition file by running the following command:

$ butane storage.bu

Example output

{"ignition":{"version":"3.2.0"},"storage":{"disks":[{"device":"/dev/disk/by-path/pci-0000:00:17.0-ata-1.0","partitions":[{"label":"var-lib-containers","sizeMiB":0,"startMiB":250000}],"wipeTable":false}],"filesystems":[{"device":"/dev/disk/by-partlabel/var-lib-containers","format":"xfs","mountOptions":["defaults","prjquota"],"path":"/var/lib/containers","wipeFilesystem":true}]},"systemd":{"units":[{"contents":"# Generated by Butane\n[Unit]\nRequires=systemd-fsck@dev-disk-by\\x2dpartlabel-var\\x2dlib\\x2dcontainers.service\nAfter=systemd-fsck@dev-disk-by\\x2dpartlabel-var\\x2dlib\\x2dcontainers.service\n\n[Mount]\nWhere=/var/lib/containers\nWhat=/dev/disk/by-partlabel/var-lib-containers\nType=xfs\nOptions=defaults,prjquota\n\n[Install]\nRequiredBy=local-fs.target","enabled":true,"name":"var-lib-containers.mount"}]}}

Copy the output into the .spec.clusters.nodes.ignitionConfigOverride field in the SiteConfig CR:

[...]
spec:
  clusters:
    - nodes:
        - hostName: <name>
          ignitionConfigOverride: '{"ignition":{"version":"3.2.0"},"storage":{"disks":[{"device":"/dev/disk/by-path/pci-0000:00:17.0-ata-1.0","partitions":[{"label":"var-lib-containers","sizeMiB":0,"startMiB":250000}],"wipeTable":false}],"filesystems":[{"device":"/dev/disk/by-partlabel/var-lib-containers","format":"xfs","mountOptions":["defaults","prjquota"],"path":"/var/lib/containers","wipeFilesystem":true}]},"systemd":{"units":[{"contents":"# Generated by Butane\n[Unit]\nRequires=systemd-fsck@dev-disk-by\\x2dpartlabel-var\\x2dlib\\x2dcontainers.service\nAfter=systemd-fsck@dev-disk-by\\x2dpartlabel-var\\x2dlib\\x2dcontainers.service\n\n[Mount]\nWhere=/var/lib/containers\nWhat=/dev/disk/by-partlabel/var-lib-containers\nType=xfs\nOptions=defaults,prjquota\n\n[Install]\nRequiredBy=local-fs.target","enabled":true,"name":"var-lib-containers.mount"}]}}'
[...]

Verification

During or after installation, verify on the hub cluster that the BareMetalHost object shows the annotation by running the following command:

$ oc get bmh -n my-sno-ns my-sno -ojson | jq '.metadata.annotations["bmac.agent-install.openshift.io/ignition-config-overrides"]'

Example output

"{\"ignition\":{\"version\":\"3.2.0\"},\"storage\":{\"disks\":[{\"device\":\"/dev/disk/by-path/pci-0000:00:17.0-ata-1.0\",\"partitions\":[{\"label\":\"var-lib-containers\",\"sizeMiB\":0,\"startMiB\":250000}],\"wipeTable\":false}],\"filesystems\":[{\"device\":\"/dev/disk/by-partlabel/var-lib-containers\",\"format\":\"xfs\",\"mountOptions\":[\"defaults\",\"prjquota\"],\"path\":\"/var/lib/containers\",\"wipeFilesystem\":true}]},\"systemd\":{\"units\":[{\"contents\":\"# Generated by Butane\\n[Unit]\\nRequires=systemd-fsck@dev-disk-by\\\\x2dpartlabel-var\\\\x2dlib\\\\x2dcontainers.service\\nAfter=systemd-fsck@dev-disk-by\\\\x2dpartlabel-var\\\\x2dlib\\\\x2dcontainers.service\\n\\n[Mount]\\nWhere=/var/lib/containers\\nWhat=/dev/disk/by-partlabel/var-lib-containers\\nType=xfs\\nOptions=defaults,prjquota\\n\\n[Install]\\nRequiredBy=local-fs.target\",\"enabled\":true,\"name\":\"var-lib-containers.mount\"}]}}"

After installation, check the single-node OpenShift disk status by running the following commands:

# lsblk

Example output

NAME   MAJ:MIN RM   SIZE RO TYPE MOUNTPOINTS
sda      8:0    0 446.6G  0 disk
├─sda1   8:1    0     1M  0 part
├─sda2   8:2    0   127M  0 part
├─sda3   8:3    0   384M  0 part /boot
├─sda4   8:4    0 243.6G  0 part /var
│                                /sysroot/ostree/deploy/rhcos/var
│                                /usr
│                                /etc
│                                /
│                                /sysroot
└─sda5   8:5    0 202.5G  0 part /var/lib/containers

# df -h

Example output

Filesystem      Size  Used Avail Use% Mounted on
devtmpfs        4.0M     0  4.0M   0% /dev
tmpfs           126G   84K  126G   1% /dev/shm
tmpfs            51G   93M   51G   1% /run
/dev/sda4       244G  5.2G  239G   3% /sysroot
tmpfs           126G  4.0K  126G   1% /tmp
/dev/sda5       203G  119G   85G  59% /var/lib/containers
/dev/sda3       350M  110M  218M  34% /boot
tmpfs            26G     0   26G   0% /run/user/1000

Additional resources

Installing Butane