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Chapter 7. Updating a cluster using the CLI

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You can update, or upgrade, an OpenShift Container Platform cluster within a minor version by using the OpenShift CLI (oc). You can also update a cluster between minor versions by following the same instructions.

7.1. Prerequisites

  • Have access to the cluster as a user with admin privileges. See Using RBAC to define and apply permissions.
  • Have a recent etcd backup in case your update fails and you must restore your cluster to a previous state.
  • Ensure all Operators previously installed through Operator Lifecycle Manager (OLM) are updated to their latest version in their latest channel. Updating the Operators ensures they have a valid update path when the default OperatorHub catalogs switch from the current minor version to the next during a cluster update. See Updating installed Operators for more information.
  • If your cluster uses manually maintained credentials, ensure that the Cloud Credential Operator (CCO) is in an upgradeable state. For more information, see Upgrading clusters with manually maintained credentials for AWS, Azure, or GCP.
  • If your cluster uses manually maintained credentials with the AWS Security Token Service (STS), obtain a copy of the ccoctl utility from the release image being updated to and use it to process any updated credentials. For more information, see Upgrading an OpenShift Container Platform cluster configured for manual mode with STS.
  • Ensure that you address all Upgradeable=False conditions so the cluster allows an update to the next minor version. You can run the oc adm upgrade command for an output of all Upgradeable=False conditions and the condition reasoning to help you prepare for a minor version update.
  • If you run an Operator or you have configured any application with the pod disruption budget, you might experience an interruption during the upgrade process. If minAvailable is set to 1 in PodDisruptionBudget, the nodes are drained to apply pending machine configs which might block the eviction process. If several nodes are rebooted, all the pods might run on only one node, and the PodDisruptionBudget field can prevent the node drain.
Important
  • When an update is failing to complete, the Cluster Version Operator (CVO) reports the status of any blocking components while attempting to reconcile the update. Rolling your cluster back to a previous version is not supported. If your update is failing to complete, contact Red Hat support.
  • Using the unsupportedConfigOverrides section to modify the configuration of an Operator is unsupported and might block cluster updates. You must remove this setting before you can update your cluster.

Additional resources

7.2. Pausing a MachineHealthCheck resource

During the upgrade process, nodes in the cluster might become temporarily unavailable. In the case of worker nodes, the machine health check might identify such nodes as unhealthy and reboot them. To avoid rebooting such nodes, pause all the MachineHealthCheck resources before updating the cluster.

Prerequisites

  • Install the OpenShift CLI (oc).

Procedure

  1. To list all the available MachineHealthCheck resources that you want to pause, run the following command: 

    $ oc get machinehealthcheck -n openshift-machine-api

  2. To pause the machine health checks, add the cluster.x-k8s.io/paused="" annotation to the MachineHealthCheck resource. Run the following command: 

    $ oc -n openshift-machine-api annotate mhc <mhc-name> cluster.x-k8s.io/paused=""

    The annotated MachineHealthCheck resource resembles the following YAML file: 

    apiVersion: machine.openshift.io/v1beta1
kind: MachineHealthCheck
metadata:
  name: example
  namespace: openshift-machine-api
  annotations:
    cluster.x-k8s.io/paused: ""
spec:
  selector:
    matchLabels:
      role: worker
  unhealthyConditions:
  - type:    "Ready"
    status:  "Unknown"
    timeout: "300s"
  - type:    "Ready"
    status:  "False"
    timeout: "300s"
  maxUnhealthy: "40%"
status:
  currentHealthy: 5
  expectedMachines: 5
    Important

    Resume the machine health checks after updating the cluster. To resume the check, remove the pause annotation from the MachineHealthCheck resource by running the following command: 

    $ oc -n openshift-machine-api annotate mhc <mhc-name> cluster.x-k8s.io/paused-

7.3. About updating single node OpenShift Container Platform

You can update, or upgrade, a single-node OpenShift Container Platform cluster by using either the console or CLI.

However, note the following limitations:

  • The prerequisite to pause the MachineHealthCheck resources is not required because there is no other node to perform the health check.
  • Restoring a single-node OpenShift Container Platform cluster using an etcd backup is not officially supported. However, it is good practice to perform the etcd backup in case your upgrade fails. If your control plane is healthy, you might be able to restore your cluster to a previous state by using the backup.

  • Updating a single-node OpenShift Container Platform cluster requires downtime and can include an automatic reboot. The amount of downtime depends on the update payload, as described in the following scenarios:

    • If the update payload contains an operating system update, which requires a reboot, the downtime is significant and impacts cluster management and user workloads.
    • If the update contains machine configuration changes that do not require a reboot, the downtime is less, and the impact on the cluster management and user workloads is lessened. In this case, the node draining step is skipped with single-node OpenShift Container Platform because there is no other node in the cluster to reschedule the workloads to.
    • If the update payload does not contain an operating system update or machine configuration changes, a short API outage occurs and resolves quickly.
Important

There are conditions, such as bugs in an updated package, that can cause the single node to not restart after a reboot. In this case, the update does not rollback automatically.

Additional resources

7.4. Updating a cluster by using the CLI

If updates are available, you can update your cluster by using the OpenShift CLI (oc).

You can find information about available OpenShift Container Platform advisories and updates in the errata section of the Customer Portal.

Prerequisites

  • Install the OpenShift CLI (oc) that matches the version for your updated version.
  • Log in to the cluster as user with cluster-admin privileges.
  • Install the jq package.
  • Pause all MachineHealthCheck resources.

Procedure

  1. Ensure that your cluster is available: 

    $ oc get clusterversion

    Example output

    NAME      VERSION   AVAILABLE   PROGRESSING   SINCE   STATUS
version   4.8.13     True        False         158m    Cluster version is 4.8.13

  2. Review the current update channel information and confirm that your channel is set to stable-4.9: 

    $ oc get clusterversion -o json|jq ".items[0].spec"

    Example output

    {
  "channel": "stable-4.9",
  "clusterID": "990f7ab8-109b-4c95-8480-2bd1deec55ff"
}

    Important

    For production clusters, you must subscribe to a stable-*, eus-* or fast-* channel.

  3. View the available updates and note the version number of the update that you want to apply: 

    $ oc adm upgrade

    Example output

    Cluster version is 4.8.13

Updates:

VERSION IMAGE
4.9.0   quay.io/openshift-release-dev/ocp-release@sha256:9c5f0df8b192a0d7b46cd5f6a4da2289c155fd5302dec7954f8f06c878160b8b

  4. Apply an update:

    • To update to the latest version: 

      $ oc adm upgrade --to-latest=true 1

    • To update to a specific version: 

      $ oc adm upgrade --to=<version> 1
      1 1
      <version> is the update version that you obtained from the output of the previous command.

  5. Review the status of the Cluster Version Operator: 

    $ oc get clusterversion -o json|jq ".items[0].spec"

    Example output

    {
  "channel": "stable-4.9",
  "clusterID": "990f7ab8-109b-4c95-8480-2bd1deec55ff",
  "desiredUpdate": {
    "force": false,
    "image": "quay.io/openshift-release-dev/ocp-release@sha256:9c5f0df8b192a0d7b46cd5f6a4da2289c155fd5302dec7954f8f06c878160b8b",
    "version": "4.9.0" 1
  }
}

    1
    If the version number in the desiredUpdate stanza matches the value that you specified, the update is in progress.

  6. Review the cluster version status history to monitor the status of the update. It might take some time for all the objects to finish updating. 

    $ oc get clusterversion -o json|jq ".items[0].status.history"

    Example output

    [
  {
    "completionTime": null,
    "image": "quay.io/openshift-release-dev/ocp-release@sha256:b8fa13e09d869089fc5957c32b02b7d3792a0b6f36693432acc0409615ab23b7",
    "startedTime": "2021-01-28T20:30:50Z",
    "state": "Partial",
    "verified": true,
    "version": "4.9.0"
  },
  {
    "completionTime": "2021-01-28T20:30:50Z",
    "image": "quay.io/openshift-release-dev/ocp-release@sha256:b8fa13e09d869089fc5957c32b02b7d3792a0b6f36693432acc0409615ab23b7",
    "startedTime": "2021-01-28T17:38:10Z",
    "state": "Completed",
    "verified": false,
    "version": "4.8.13"
  }
]

    The history contains a list of the most recent versions applied to the cluster. This value is updated when the CVO applies an update. The list is ordered by date, where the newest update is first in the list. Updates in the history have state Completed if the rollout completed and Partial if the update failed or did not complete.

  7. After the update completes, you can confirm that the cluster version has updated to the new version: 

    $ oc get clusterversion

    Example output

    NAME      VERSION     AVAILABLE   PROGRESSING   SINCE     STATUS
version   4.9.0       True        False         2m        Cluster version is 4.9.0

    Note

    If the oc get clusterversion command displays the following error while the PROGRESSING status is True, you can ignore the error. 

    NAME    VERSION AVAILABLE PROGRESSING SINCE STATUS
version 4.10.26 True      True        24m   Unable to apply 4.11.0-rc.7: an unknown error has occurred: MultipleErrors

  8. If you are upgrading your cluster to the next minor version, like version 4.y to 4.(y+1), it is recommended to confirm your nodes are updated before deploying workloads that rely on a new feature: 

    $ oc get nodes

    Example output

    NAME                           STATUS   ROLES    AGE   VERSION
ip-10-0-168-251.ec2.internal   Ready    master   82m   v1.22.1
ip-10-0-170-223.ec2.internal   Ready    master   82m   v1.22.1
ip-10-0-179-95.ec2.internal    Ready    worker   70m   v1.22.1
ip-10-0-182-134.ec2.internal   Ready    worker   70m   v1.22.1
ip-10-0-211-16.ec2.internal    Ready    master   82m   v1.22.1
ip-10-0-250-100.ec2.internal   Ready    worker   69m   v1.22.1

7.5. Changing the update server by using the CLI

Changing the update server is optional. If you have an OpenShift Update Service (OSUS) installed and configured locally, you must set the URL for the server as the upstream to use the local server during updates. The default value for upstream is https://api.openshift.com/api/upgrades_info/v1/graph.

Procedure

  • Change the upstream parameter value in the cluster version: 

    $ oc patch clusterversion/version --patch '{"spec":{"upstream":"<update-server-url>"}}' --type=merge

    The <update-server-url> variable specifies the URL for the update server.

    Example output

    clusterversion.config.openshift.io/version patched

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