Chapter 4. Configure storage for OpenShift Container Platform services

You can use OpenShift Data Foundation to provide storage for OpenShift Container Platform services such as image registry, monitoring, and logging.

The process for configuring storage for these services depends on the infrastructure used in your OpenShift Data Foundation deployment.

Warning

Always ensure that you have plenty of storage capacity for these services. If the storage for these critical services runs out of space, the cluster becomes inoperable and very difficult to recover.

Red Hat recommends configuring shorter curation and retention intervals for these services. See Configuring the Curator schedule and the Modifying retention time for Prometheus metrics data of Monitoring guide in the OpenShift Container Platform documentation for details.

If you do run out of storage space for these services, contact Red Hat Customer Support.

4.1. Configuring Image Registry to use OpenShift Data Foundation

OpenShift Container Platform provides a built in Container Image Registry which runs as a standard workload on the cluster. A registry is typically used as a publication target for images built on the cluster as well as a source of images for workloads running on the cluster.

Follow the instructions in this section to configure OpenShift Data Foundation as storage for the Container Image Registry. On AWS, it is not required to change the storage for the registry. However, it is recommended to change the storage to OpenShift Data Foundation Persistent Volume for vSphere and Bare metal platforms.

Warning

This process does not migrate data from an existing image registry to the new image registry. If you already have container images in your existing registry, back up your registry before you complete this process, and re-register your images when this process is complete.

Prerequisites

  • You have administrative access to OpenShift Web Console.
  • OpenShift Data Foundation Operator is installed and running in the openshift-storage namespace. In OpenShift Web Console, click Operators → Installed Operators to view installed operators.
  • Image Registry Operator is installed and running in the openshift-image-registry namespace. In OpenShift Web Console, click Administration → Cluster Settings → Cluster Operators to view cluster operators.
  • A storage class with provisioner openshift-storage.cephfs.csi.ceph.com is available. In OpenShift Web Console, click Storage → StorageClasses to view available storage classes.

Procedure

  1. Create a Persistent Volume Claim for the Image Registry to use.

    1. In the OpenShift Web Console, click Storage → Persistent Volume Claims.
    2. Set the Project to openshift-image-registry.

    3. Click Create Persistent Volume Claim.

      1. From the list of available storage classes retrieved above, specify the Storage Class with the provisioner openshift-storage.cephfs.csi.ceph.com.
      2. Specify the Persistent Volume Claim Name, for example, ocs4registry.
      3. Specify an Access Mode of Shared Access (RWX).
      4. Specify a Size of at least 100 GB.

      5. Click Create.

        Wait until the status of the new Persistent Volume Claim is listed as Bound.

  2. Configure the cluster’s Image Registry to use the new Persistent Volume Claim.

    1. Click Administration → Custom Resource Definitions.
    2. Click the Config custom resource definition associated with the imageregistry.operator.openshift.io group.
    3. Click the Instances tab.
    4. Beside the cluster instance, click the Action Menu (⋮) → Edit Config.

    5. Add the new Persistent Volume Claim as persistent storage for the Image Registry.

      1. Add the following under spec:, replacing the existing storage: section if necessary. 

          storage:
    pvc:
      claim: <new-pvc-name>

        For example: 

          storage:
    pvc:
      claim: ocs4registry
      2. Click Save.

  3. Verify that the new configuration is being used.

    1. Click Workloads → Pods.
    2. Set the Project to openshift-image-registry.
    3. Verify that the new image-registry-* pod appears with a status of Running, and that the previous image-registry-* pod terminates.
    4. Click the new image-registry-* pod to view pod details.
    5. Scroll down to Volumes and verify that the registry-storage volume has a Type that matches your new Persistent Volume Claim, for example, ocs4registry.

4.2. Configuring monitoring to use OpenShift Data Foundation

OpenShift Data Foundation provides a monitoring stack that comprises of Prometheus and Alert Manager.

Follow the instructions in this section to configure OpenShift Data Foundation as storage for the monitoring stack.

Important

Monitoring will not function if it runs out of storage space. Always ensure that you have plenty of storage capacity for monitoring.

Red Hat recommends configuring a short retention interval for this service. See the Modifying retention time for Prometheus metrics data of Monitoring guide in the OpenShift Container Platform documentation for details.

Prerequisites

  • You have administrative access to OpenShift Web Console.
  • OpenShift Data Foundation Operator is installed and running in the openshift-storage namespace. In the OpenShift Web Console, click Operators → Installed Operators to view installed operators.
  • Monitoring Operator is installed and running in the openshift-monitoring namespace. In the OpenShift Web Console, click Administration → Cluster Settings → Cluster Operators to view cluster operators.
  • A storage class with provisioner openshift-storage.rbd.csi.ceph.com is available. In the OpenShift Web Console, click Storage → StorageClasses to view available storage classes.

Procedure

  1. In the OpenShift Web Console, go to Workloads → Config Maps.
  2. Set the Project dropdown to openshift-monitoring.
  3. Click Create Config Map.

  4. Define a new cluster-monitoring-config Config Map using the following example.

    Replace the content in angle brackets (<, >) with your own values, for example, retention: 24h or storage: 40Gi.

    Replace the storageClassName with the storageclass that uses the provisioner openshift-storage.rbd.csi.ceph.com. In the example given below the name of the storageclass is ocs-storagecluster-ceph-rbd.

    Example cluster-monitoring-config Config Map

    apiVersion: v1
kind: ConfigMap
metadata:
  name: cluster-monitoring-config
  namespace: openshift-monitoring
data:
  config.yaml: |
      prometheusK8s:
        retention: <time to retain monitoring files, e.g. 24h>
        volumeClaimTemplate:
          metadata:
            name: ocs-prometheus-claim
          spec:
            storageClassName: ocs-storagecluster-ceph-rbd
            resources:
              requests:
                storage: <size of claim, e.g. 40Gi>
      alertmanagerMain:
        volumeClaimTemplate:
          metadata:
            name: ocs-alertmanager-claim
          spec:
            storageClassName: ocs-storagecluster-ceph-rbd
            resources:
              requests:
                storage: <size of claim, e.g. 40Gi>

  5. Click Create to save and create the Config Map.

Verification steps

  1. Verify that the Persistent Volume Claims are bound to the pods.

    1. Go to Storage → Persistent Volume Claims.
    2. Set the Project dropdown to openshift-monitoring.

    3. Verify that 5 Persistent Volume Claims are visible with a state of Bound, attached to three alertmanager-main-* pods, and two prometheus-k8s-* pods.

      Figure 4.1. Monitoring storage created and bound

      Screenshot of OpenShift Web Console showing five pods with persistent volume claims bound in the openshift-monitoring project

  2. Verify that the new alertmanager-main-* pods appear with a state of Running.

    1. Go to Workloads → Pods.
    2. Click the new alertmanager-main-* pods to view the pod details.

    3. Scroll down to Volumes and verify that the volume has a Type, ocs-alertmanager-claim that matches one of your new Persistent Volume Claims, for example, ocs-alertmanager-claim-alertmanager-main-0.

      Figure 4.2. Persistent Volume Claims attached to alertmanager-main-* pod

      Screenshot of OpenShift Web Console showing persistent volume claim attached to the altermanager pod

  3. Verify that the new prometheus-k8s-* pods appear with a state of Running.

    1. Click the new prometheus-k8s-* pods to view the pod details.

    2. Scroll down to Volumes and verify that the volume has a Type, ocs-prometheus-claim that matches one of your new Persistent Volume Claims, for example, ocs-prometheus-claim-prometheus-k8s-0.

      Figure 4.3. Persistent Volume Claims attached to prometheus-k8s-* pod

      Screenshot of OpenShift Web Console showing persistent volume claim attached to the prometheus pod

4.3. Overprovision level policy control [Technology Preview]

Overprovision control is a mechanism that enables you to define a quota on the amount of Persistent Volume Claims (PVCs) consumed from a storage cluster, based on the specific application namespace.

When you enable the overprovision control mechanism, it prevents you from overprovisioning the PVCs consumed from the storage cluster. OpenShift provides flexibility for defining constraints that limit the aggregated resource consumption at cluster scope with the help of ClusterResourceQuota. For more information see, OpenShift ClusterResourceQuota.

With overprovision control, a ClusteResourceQuota is initiated, and you can set the storage capacity limit for each storage class. The alarm triggers when 80% of the capacity limit is consumed.

Note

Overprovision level policy control is a Technology Preview feature. Technology Preview features are not supported with Red Hat production service level agreements (SLAs) and might not be functionally complete. Red Hat does not recommend using them in production. These features provide early access to upcoming product features, enabling customers to test functionality and provide feedback during the development process. For more information, refer to Technology Preview Features Support Scope.

For more information about OpenShift Data Foundation deployment, refer to Product Documentation and select the deployment procedure according to the platform.

Prerequisites

  • Ensure that the OpenShift Data Foundation cluster is created.

Procedure

  1. Deploy storagecluster either from the command line interface or the user interface.

  2. Label the application namespace. 

    apiVersion: v1
kind: Namespace
metadata:
     name: <desired_name>
     labels:
          storagequota: <desired_label>
    <desired_name>
    Specify a name for the application namespace, for example, quota-rbd.
    <desired_label>
    Specify a label for the storage quota, for example, storagequota1.

  3. Edit the storagecluster to set the quota limit on the storage class. 

    $ oc edit storagecluster -n openshift-storage <ocs_storagecluster_name>
    <ocs_storagecluster_name>
    Specify the name of the storage cluster.

  4. Add an entry for Overprovision Control with the desired hard limit into the StorageCluster.Spec: 

    apiVersion: ocs.openshift.io/v1
kind: StorageCluster
spec:
 [...]
     overprovisionControl:
     - capacity: <desired_quota_limit>
          storageClassName: <storage_class_name>
          quotaName: <desired_quota_name>
          selector:
            labels:
                   matchLabels:
                    storagequota: <desired_label>
[...]
    <desired_quota_limit>
    Specify a desired quota limit for the storage class, for example, 27Ti.
    <storage_class_name>
    Specify the name of the storage class for which you want to set the quota limit, for example, ocs-storagecluster-ceph-rbd.
    <desired_quota_name>
    Specify a name for the storage quota, for example, quota1.
    <desired_label>
    Specify a label for the storage quota, for example, storagequota1.
  5. Save the modified storagecluster.

  6. Verify that the clusterresourcequota is defined.

    Note

    Expect the clusterresourcequota with the quotaName that you defined in the previous step, for example, quota1. 

    $ oc get clusterresourcequota -A

$ oc describe clusterresourcequota -A

4.4. Cluster logging for OpenShift Data Foundation

You can deploy cluster logging to aggregate logs for a range of OpenShift Container Platform services. For information about how to deploy cluster logging, see Deploying cluster logging.

Upon initial OpenShift Container Platform deployment, OpenShift Data Foundation is not configured by default and the OpenShift Container Platform cluster will solely rely on default storage available from the nodes. You can edit the default configuration of OpenShift logging (ElasticSearch) to be backed by OpenShift Data Foundation to have OpenShift Data Foundation backed logging (Elasticsearch).

Important

Always ensure that you have plenty of storage capacity for these services. If you run out of storage space for these critical services, the logging application becomes inoperable and very difficult to recover.

Red Hat recommends configuring shorter curation and retention intervals for these services. See Cluster logging curator in the OpenShift Container Platform documentation for details.

If you run out of storage space for these services, contact Red Hat Customer Support.

4.4.1. Configuring persistent storage

You can configure a persistent storage class and size for the Elasticsearch cluster using the storage class name and size parameters. The Cluster Logging Operator creates a Persistent Volume Claim for each data node in the Elasticsearch cluster based on these parameters. For example: 

spec:
    logStore:
      type: "elasticsearch"
      elasticsearch:
        nodeCount: 3
        storage:
          storageClassName: "ocs-storagecluster-ceph-rbd”
          size: "200G"

This example specifies that each data node in the cluster will be bound to a Persistent Volume Claim that requests 200GiB of ocs-storagecluster-ceph-rbd storage. Each primary shard will be backed by a single replica. A copy of the shard is replicated across all the nodes and are always available and the copy can be recovered if at least two nodes exist due to the single redundancy policy. For information about Elasticsearch replication policies, see Elasticsearch replication policy in About deploying and configuring cluster logging.

Note

Omission of the storage block will result in a deployment backed by default storage. For example: 

spec:
    logStore:
      type: "elasticsearch"
      elasticsearch:
        nodeCount: 3
        storage: {}

For more information, see Configuring cluster logging.

4.4.2. Configuring cluster logging to use OpenShift data Foundation

Follow the instructions in this section to configure OpenShift Data Foundation as storage for the OpenShift cluster logging.

Note

You can obtain all the logs when you configure logging for the first time in OpenShift Data Foundation. However, after you uninstall and reinstall logging, the old logs are removed and only the new logs are processed.

Prerequisites

  • You have administrative access to OpenShift Web Console.
  • OpenShift Data Foundation Operator is installed and running in the openshift-storage namespace.
  • Cluster logging Operator is installed and running in the openshift-logging namespace.

Procedure

  1. Click Administration → Custom Resource Definitions from the left pane of the OpenShift Web Console.
  2. On the Custom Resource Definitions page, click ClusterLogging.
  3. On the Custom Resource Definition Overview page, select View Instances from the Actions menu or click the Instances Tab.

  4. On the Cluster Logging page, click Create Cluster Logging.

    You might have to refresh the page to load the data.

  5. In the YAML, replace the storageClassName with the storageclass that uses the provisioner openshift-storage.rbd.csi.ceph.com. In the example given below the name of the storageclass is ocs-storagecluster-ceph-rbd: 

    apiVersion: "logging.openshift.io/v1"
kind: "ClusterLogging"
metadata:
  name: "instance"
  namespace: "openshift-logging"
spec:
  managementState: "Managed"
  logStore:
    type: "elasticsearch"
    elasticsearch:
      nodeCount: 3
      storage:
        storageClassName: ocs-storagecluster-ceph-rbd
        size: 200G # Change as per your requirement
      redundancyPolicy: "SingleRedundancy"
  visualization:
    type: "kibana"
    kibana:
      replicas: 1
  curation:
    type: "curator"
    curator:
      schedule: "30 3 * * *"
  collection:
    logs:
      type: "fluentd"
      fluentd: {}

    If you have tainted the OpenShift Data Foundation nodes, you must add toleration to enable scheduling of the daemonset pods for logging. 

    spec:
[...]
  collection:
    logs:
      fluentd:
        tolerations:
        - effect: NoSchedule
          key: node.ocs.openshift.io/storage
          value: 'true'
      type: fluentd
  6. Click Save.

Verification steps

  1. Verify that the Persistent Volume Claims are bound to the elasticsearch pods.

    1. Go to Storage → Persistent Volume Claims.
    2. Set the Project dropdown to openshift-logging.

    3. Verify that Persistent Volume Claims are visible with a state of Bound, attached to elasticsearch-* pods.

      Figure 4.4. Cluster logging created and bound

      Screenshot of Persistent Volume Claims with a bound state attached to elasticsearch pods

  2. Verify that the new cluster logging is being used.

    1. Click Workload → Pods.
    2. Set the Project to openshift-logging.
    3. Verify that the new elasticsearch-* pods appear with a state of Running.
    4. Click the new elasticsearch-* pod to view pod details.
    5. Scroll down to Volumes and verify that the elasticsearch volume has a Type that matches your new Persistent Volume Claim, for example, elasticsearch-elasticsearch-cdm-9r624biv-3.
    6. Click the Persistent Volume Claim name and verify the storage class name in the PersistentVolumeClaim Overview page.
Note

Make sure to use a shorter curator time to avoid PV full scenario on PVs attached to Elasticsearch pods.

You can configure Curator to delete Elasticsearch data based on retention settings. It is recommended that you set the following default index data retention of 5 days as a default. 

config.yaml: |
    openshift-storage:
      delete:
        days: 5

For more details, see Curation of Elasticsearch Data.

Note

To uninstall the cluster logging backed by Persistent Volume Claim, use the procedure removing the cluster logging operator from OpenShift Data Foundation in the uninstall chapter of the respective deployment guide.