OpenShift Container Platform exposes metrics that the Cluster Monitoring Operator collects and stores in the Prometheus-based monitoring stack. As an OpenShift Container Platform administrator, you can view system resources, containers and components metrics in one dashboard interface, Grafana.

Prometheus database storage requirements

Red Hat performed various tests for different scale sizes.

Table 1. Prometheus Database storage requirements based on number of nodes/pods in the cluster
Number of Nodes Number of Pods Prometheus storage growth per day Prometheus storage growth per 15 days RAM Space (per scale size) Network (per tsdb chunk)

50

1800

6.3 GB

94 GB

6 GB

16 MB

100

3600

13 GB

195 GB

10 GB

26 MB

150

5400

19 GB

283 GB

12 GB

36 MB

200

7200

25 GB

375 GB

14 GB

46 MB

Approximately 20 percent of the expected size was added as overhead to ensure that the storage requirements do not exceed the calculated value.

The above calculation is for the default OpenShift Container Platform Cluster Monitoring Operator.

CPU utilization has minor impact. The ratio is approximately 1 core out of 40 per 50 nodes and 1800 pods.

Lab environment

In a previous release, all experiments were performed in an OpenShift Container Platform on OpenStack environment:

  • Infra nodes (VMs) - 40 cores, 157 GB RAM.

  • CNS nodes (VMs) - 16 cores, 62 GB RAM, NVMe drives.

Currently, OpenStack environments are not supported for OpenShift Container Platform 4.2.

Recommendations for OpenShift Container Platform

  • Use at least three infrastructure (infra) nodes.

  • Use at least three openshift-container-storage nodes with non-volatile memory express (NVMe) drives.

OpenShift Container Storage (OCS) is currently a Technology Preview feature. Technology Preview features are not supported with Red Hat production service level agreements (SLAs), might not be functionally complete, and Red Hat does not recommend to use them for production. These features provide early access to upcoming product features, enabling customers to test functionality and provide feedback during the development process.

Configuring cluster monitoring

Procedure

To increase the storage capacity for Prometheus:

  1. Create a YAML configuration file, `cluster-monitoring-config.yml. For example:

    apiVersion: v1
    kind: ConfigMap
    data:
      config.yaml: |
        prometheusOperator:
          baseImage: quay.io/coreos/prometheus-operator
          prometheusConfigReloaderBaseImage: quay.io/coreos/prometheus-config-reloader
          configReloaderBaseImage: quay.io/coreos/configmap-reload
          nodeSelector:
            node-role.kubernetes.io/infra: ""
        prometheusK8s:
          retention: {{PROMETHEUS_RETENTION_PERIOD}} (1)
          baseImage: openshift/prometheus
          nodeSelector:
            node-role.kubernetes.io/infra: ""
          volumeClaimTemplate:
            spec:
              storageClassName: gp2
              resources:
                requests:
                  storage: {{PROMETHEUS_STORAGE_SIZE}} (2)
        alertmanagerMain:
          baseImage: openshift/prometheus-alertmanager
          nodeSelector:
            node-role.kubernetes.io/infra: ""
          volumeClaimTemplate:
            spec:
              storageClassName: gp2
              resources:
                requests:
                  storage: {{ALERTMANAGER_STORAGE_SIZE}} (3)
        nodeExporter:
          baseImage: openshift/prometheus-node-exporter
        kubeRbacProxy:
          baseImage: quay.io/coreos/kube-rbac-proxy
        kubeStateMetrics:
          baseImage: quay.io/coreos/kube-state-metrics
          nodeSelector:
            node-role.kubernetes.io/infra: ""
        grafana:
          baseImage: grafana/grafana
          nodeSelector:
            node-role.kubernetes.io/infra: ""
        auth:
          baseImage: openshift/oauth-proxy
        k8sPrometheusAdapter:
          nodeSelector:
            node-role.kubernetes.io/infra: ""
    metadata:
      name: cluster-monitoring-config
    namespace: openshift-monitoring
    1 A typical value is PROMETHEUS_RETENTION_PERIOD=15d. Units are measured in time using one of these suffixes: s, m, h, d.
    2 A typical value is PROMETHEUS_STORAGE_SIZE=2000Gi. Storage values can be a plain integer or as a fixed-point integer using one of these suffixes: E, P, T, G, M, K. You can also use the power-of-two equivalents: Ei, Pi, Ti, Gi, Mi, Ki.
    3 A typical value is ALERTMANAGER_STORAGE_SIZE=20Gi. Storage values can be a plain integer or as a fixed-point integer using one of these suffixes: E, P, T, G, M, K. You can also use the power-of-two equivalents: Ei, Pi, Ti, Gi, Mi, Ki.
  2. Set the values like the retention period and storage sizes.

  3. Apply the changes by running:

    $ oc create -f cluster-monitoring-config.yml