Red Hat OpenShift Container Platform

Move the monitoring solution

Redeploy the monitoring stack to infrastructure nodes to reduce your subscription requirements. Create and apply a custom config map to move the monitoring stack to infrastructure nodes. The monitoring stack includes Prometheus, Thanos Querier, and Alertmanager, and is managed by the Cluster Monitoring Operator (CMO).

Prerequisites

You have access to the cluster as a user with the cluster-admin cluster role.
You have created the cluster-monitoring-config ConfigMap object.
You have installed the OpenShift CLI (oc).

Procedure

Edit the cluster-monitoring-config config map and change the nodeSelector to use the infra label by running the following command:

$ oc edit configmap cluster-monitoring-config -n openshift-monitoring

apiVersion: v1
kind: ConfigMap
metadata:
  name: cluster-monitoring-config
  namespace: openshift-monitoring
data:
  config.yaml: |+
    alertmanagerMain:
      nodeSelector:
        node-role.kubernetes.io/infra: ""
      tolerations:
      - key: node-role.kubernetes.io/infra
        value: reserved
        effect: NoSchedule
    prometheusK8s:
      nodeSelector:
        node-role.kubernetes.io/infra: ""
      tolerations:
      - key: node-role.kubernetes.io/infra
        value: reserved
        effect: NoSchedule
    prometheusOperator:
      nodeSelector:
        node-role.kubernetes.io/infra: ""
      tolerations:
      - key: node-role.kubernetes.io/infra
        value: reserved
        effect: NoSchedule
    metricsServer:
      nodeSelector:
        node-role.kubernetes.io/infra: ""
      tolerations:
      - key: node-role.kubernetes.io/infra
        value: reserved
        effect: NoSchedule
    kubeStateMetrics:
      nodeSelector:
        node-role.kubernetes.io/infra: ""
      tolerations:
      - key: node-role.kubernetes.io/infra
        value: reserved
        effect: NoSchedule
    telemeterClient:
      nodeSelector:
        node-role.kubernetes.io/infra: ""
      tolerations:
      - key: node-role.kubernetes.io/infra
        value: reserved
        effect: NoSchedule
    openshiftStateMetrics:
      nodeSelector:
        node-role.kubernetes.io/infra: ""
      tolerations:
      - key: node-role.kubernetes.io/infra
        value: reserved
        effect: NoSchedule
    thanosQuerier:
      nodeSelector:
        node-role.kubernetes.io/infra: ""
      tolerations:
      - key: node-role.kubernetes.io/infra
        value: reserved
        effect: NoSchedule
    monitoringPlugin:
      nodeSelector:
        node-role.kubernetes.io/infra: ""
      tolerations:
      - key: node-role.kubernetes.io/infra
        value: reserved
        effect: NoSchedule

Add a nodeSelector parameter with the appropriate value to the component you want to move. You can use a nodeSelector parameter in the format shown or use <key>: <value> pairs, based on the value specified for the node. If you added a taint to the infrastructure node, also add a matching toleration.

Watch the monitoring pods move to the new machines by running the following command:
```
$ watch 'oc get pod -n openshift-monitoring -o wide'
```
If a component has not moved to the infra node, delete the pod with this component by running the following command:
```
$ oc delete pod -n openshift-monitoring <pod>
```
The component from the deleted pod is re-created on the infra node.