Chapter 8. Deploying on OpenStack with rootVolume and etcd on local disk

Procedure

1. Create a Nova flavor for the control plane with at least 10 GB of ephemeral disk by running the following command, replacing the values for --ram, --disk, and <flavor_name> based on your environment:

   $ openstack flavor create --<ram 16384> --<disk 0> --ephemeral 10 --vcpus 4 <flavor_name>

2. Deploy a cluster with root volumes for the control plane; for example:

   Example YAML file

   # ...
   controlPlane:
     name: master
     platform:
       openstack:
         type: ${CONTROL_PLANE_FLAVOR}
         rootVolume:
           size: 25
           types:
           - ${CINDER_TYPE}
     replicas: 3
   # ...

3. Deploy the cluster you created by running the following command:

   $ openshift-install create cluster --dir <installation_directory> 1

   1

   For <installation_directory>, specify the location of the customized ./install-config.yaml file that you previously created.

4. Verify that the cluster you deployed is healthy before proceeding to the next step by running the following command:

   $ oc wait clusteroperators --all --for=condition=Progressing=false 1

   1

   Ensures that the cluster operators are finished progressing and that the cluster is not deploying or updating.

5. Edit the ControlPlaneMachineSet (CPMS) to add the additional block ephemeral device that is used by etcd by running the following command:

   $ oc patch ControlPlaneMachineSet/cluster -n openshift-machine-api --type json -p ' 1
   [
       {
         "op": "add",
         "path": "/spec/template/machines_v1beta1_machine_openshift_io/spec/providerSpec/value/additionalBlockDevices", 2
         "value": [
           {
             "name": "etcd",
             "sizeGiB": 10,
             "storage": {
               "type": "Local" 3
             }
           }
         ]
       }
     ]
   '

   1

   Applies the JSON patch to the ControlPlaneMachineSet custom resource (CR).

   2

   Specifies the path where the additionalBlockDevices are added.

   3

   Adds the etcd devices with at least local storage of 10 GB to the cluster. You can specify values greater than 10 GB as long as the etcd device fits the Nova flavor. For example, if the Nova flavor has 15 GB, you can create the etcd device with 12 GB.

6. Verify that the control plane machines are healthy by using the following steps:

   1. Wait for the control plane machine set update to finish by running the following command:

      $ oc wait --timeout=90m --for=condition=Progressing=false controlplanemachineset.machine.openshift.io -n openshift-machine-api cluster

   2. Verify that the 3 control plane machine sets are updated by running the following command:

      $ oc wait --timeout=90m --for=jsonpath='{.status.updatedReplicas}'=3 controlplanemachineset.machine.openshift.io -n openshift-machine-api cluster

   3. Verify that the 3 control plane machine sets are healthy by running the following command:

      $ oc wait --timeout=90m --for=jsonpath='{.status.replicas}'=3 controlplanemachineset.machine.openshift.io -n openshift-machine-api cluster

   4. Verify that the ClusterOperators are not progressing in the cluster by running the following command:

      $ oc wait clusteroperators --timeout=30m --all --for=condition=Progressing=false

   5. Verify that each of the 3 control plane machines has the additional block device you previously created by running the following script:

   $ cp_machines=$(oc get machines -n openshift-machine-api --selector='machine.openshift.io/cluster-api-machine-role=master' --no-headers -o custom-columns=NAME:.metadata.name) 1
   
   
   if [[ $(echo "${cp_machines}" | wc -l) -ne 3 ]]; then
     exit 1
   fi 2
   
   
   for machine in ${cp_machines}; do
     if ! oc get machine -n openshift-machine-api "${machine}" -o jsonpath='{.spec.providerSpec.value.additionalBlockDevices}' | grep -q 'etcd'; then
   	exit 1
     fi 3
   done

   1

   Retrieves the control plane machines running in the cluster.

   2

   Iterates over machines which have an additionalBlockDevices entry with the name etcd.

   3

   Outputs the name of every control plane machine which has an additionalBlockDevice named etcd.

7. Create a file named 98-var-lib-etcd.yaml by using the following YAML file:

   Warning

   This procedure is for testing etcd on a local disk and should not be used on a production cluster. In certain cases, complete loss of the control plane can occur. For more information, see "Overview of backup and restore operation" under "Backup and restore".

   apiVersion: machineconfiguration.openshift.io/v1
   kind: MachineConfig
   metadata:
     labels:
       machineconfiguration.openshift.io/role: master
     name: 98-var-lib-etcd
   spec:
     config:
       ignition:
         version: 3.4.0
       systemd:
         units:
         - contents: |
             [Unit]
             Description=Mount local-etcd to /var/lib/etcd
   
             [Mount]
             What=/dev/disk/by-label/local-etcd 1
             Where=/var/lib/etcd
             Type=xfs
             Options=defaults,prjquota
   
             [Install]
             WantedBy=local-fs.target
           enabled: true
           name: var-lib-etcd.mount
         - contents: |
             [Unit]
             Description=Create local-etcd filesystem
             DefaultDependencies=no
             After=local-fs-pre.target
             ConditionPathIsSymbolicLink=!/dev/disk/by-label/local-etcd 2
   
             [Service]
             Type=oneshot
             RemainAfterExit=yes
             ExecStart=/bin/bash -c "[ -L /dev/disk/by-label/ephemeral0 ] || ( >&2 echo Ephemeral disk does not exist; /usr/bin/false )"
             ExecStart=/usr/sbin/mkfs.xfs -f -L local-etcd /dev/disk/by-label/ephemeral0 3
   
             [Install]
             RequiredBy=dev-disk-by\x2dlabel-local\x2detcd.device
           enabled: true
           name: create-local-etcd.service
         - contents: |
             [Unit]
             Description=Migrate existing data to local etcd
             After=var-lib-etcd.mount
             Before=crio.service 4
   
             Requisite=var-lib-etcd.mount
             ConditionPathExists=!/var/lib/etcd/member
             ConditionPathIsDirectory=/sysroot/ostree/deploy/rhcos/var/lib/etcd/member 5
   
             [Service]
             Type=oneshot
             RemainAfterExit=yes
   
             ExecStart=/bin/bash -c "if [ -d /var/lib/etcd/member.migrate ]; then rm -rf /var/lib/etcd/member.migrate; fi" 6
   
             ExecStart=/usr/bin/cp -aZ /sysroot/ostree/deploy/rhcos/var/lib/etcd/member/ /var/lib/etcd/member.migrate
             ExecStart=/usr/bin/mv /var/lib/etcd/member.migrate /var/lib/etcd/member 7
   
             [Install]
             RequiredBy=var-lib-etcd.mount
           enabled: true
           name: migrate-to-local-etcd.service
         - contents: |
             [Unit]
             Description=Relabel /var/lib/etcd
   
             After=migrate-to-local-etcd.service
             Before=crio.service
   
             [Service]
             Type=oneshot
             RemainAfterExit=yes
   
             ExecCondition=/bin/bash -c "[ -n \"$(restorecon -nv /var/lib/etcd)\" ]" 8
   
             ExecStart=/usr/sbin/restorecon -R /var/lib/etcd
   
             [Install]
             RequiredBy=var-lib-etcd.mount
           enabled: true
           name: relabel-var-lib-etcd.service

   1

   The etcd database must be mounted by the device, not a label, to ensure that systemd generates the device dependency used in this config to trigger filesystem creation.

   2

   Do not run if the file system dev/disk/by-label/local-etcd already exists.

   3

   Fails with an alert message if /dev/disk/by-label/ephemeral0 doesn’t exist.

   4

   Migrates existing data to local etcd database. This config does so after /var/lib/etcd is mounted, but before CRI-O starts so etcd is not running yet.

   5

   Requires that etcd is mounted and does not contain a member directory, but the ostree does.

   6

   Cleans up any previous migration state.

   7

   Copies and moves in separate steps to ensure atomic creation of a complete member directory.

   8

   Performs a quick check of the mount point directory before performing a full recursive relabel. If restorecon in the file path /var/lib/etcd cannot rename the directory, the recursive rename is not performed.

8. Create the new MachineConfig object by running the following command:

   $ oc create -f 98-var-lib-etcd.yaml

   Note

   Moving the etcd database onto the local disk of each control plane machine takes time.

9. Verify that the etcd databases has been transferred to the local disk of each control plane by running the following commands:

   1. Verify that the cluster is still updating by running the following command:

      $ oc wait --timeout=45m --for=condition=Updating=false machineconfigpool/master

   2. Verify that the cluster is ready by running the following command:

      $ oc wait node --selector='node-role.kubernetes.io/master' --for condition=Ready --timeout=30s

   3. Verify that the cluster Operators are running in the cluster by running the following command:

      $ oc wait clusteroperators --timeout=30m --all --for=condition=Progressing=false