OpenShift Container Platform

Enabling machine health checks on bare metal

You can enable machine health checks on bare metal to repair and replace unhealthy managed cluster nodes automatically. You must have additional agent machines that are ready to install in the managed cluster.

Consider the following limitations before enabling machine health checks:

You cannot modify the MachineHealthCheck object.
Machine health checks replace nodes only when at least two nodes stay in the False or Unknown status for more than 8 minutes.

After you enable machine health checks for the managed cluster nodes, the MachineHealthCheck object is created in your hosted cluster.

To enable machine health checks in your hosted cluster, modify the NodePool resource.

Procedure

Verify that the spec.nodeDrainTimeout value in your NodePool resource is greater than 0s. Replace <hosted_cluster_namespace> with the name of your hosted cluster namespace and <nodepool_name> with the node pool name. Run the following command:
```
$ oc get nodepool -n <hosted_cluster_namespace> <nodepool_name> -o yaml | grep nodeDrainTimeout
```
Example output
```
nodeDrainTimeout: 30s
```

If the spec.nodeDrainTimeout value is not greater than 0s, modify the value by running the following command:

$ oc patch nodepool -n <hosted_cluster_namespace> <nodepool_name> -p '{"spec":{"nodeDrainTimeout": "30m"}}' --type=merge

Enable machine health checks by setting the spec.management.autoRepair field to true in the NodePool resource. Run the following command:
```
$ oc patch nodepool -n <hosted_cluster_namespace> <nodepool_name> -p '{"spec": {"management": {"autoRepair":true}}}' --type=merge
```
Verify that the NodePool resource is updated with the autoRepair: true value by running the following command:
```
$ oc get nodepool -n <hosted_cluster_namespace> <nodepool_name> -o yaml | grep autoRepair
```