Red Hat OpenShift Container Platform

Pausing a MachineHealthCheck resource

During the update process, nodes in the cluster might become temporarily unavailable. For worker nodes, the MachineHealthCheck resources might identify such nodes as unhealthy and reboot them. To avoid rebooting worker nodes, you must pause all the MachineHealthCheck resources before updating the cluster.

Some MachineHealthCheck resources might not need to be paused. If your MachineHealthCheck resource relies on unrecoverable conditions, pausing that MHC is unnecessary.

Prerequisites

You installed the OpenShift CLI (oc).

Procedure

List all of the available MachineHealthCheck resources that you want to pause by running the following command:
```
$ oc get machinehealthcheck -n openshift-machine-api
```

For each MachineHealthCheck resource, pause the machine health check by running 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

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-