Table of Contents

• Manually scaling a MachineSet
  • Deleting a specific machine
• Applying autoscaling to an OKD cluster
  • ClusterAutoscaler
  • MachineAutoscaler

it desribes the host of a node

group of machines

You need to cluster-admin for modifying machinesets.

oc get machinesets -n openshift-machine-api

oc scale --replicas=2 machineset <machineset> -n openshift-machine-api

or

oc edit machineset <machineset> -n openshift-machine-api

You can scale the MachineSet up or down. It takes several minutes for the new machines to be available.

https://docs.okd.io/latest/machine_management/manually-scaling-machineset.html

oc get machine -n openshift-machine-api

The command output contains a list of Machines in the <clusterid>-worker-<cloud_region> format.

oc delete machine <machine> -n openshift-machine-api

By default, the machine controller tries to drain the node that is backed by the machine until it succeeds. In some situations, such as with a misconfigured Pod disruption budget, the drain operation might not be able to succeed in preventing the machine from being deleted. You can skip draining the node by annotating "machine.openshift.io/exclude-node-draining" in a specific machine. If the machine being deleted belongs to a MachineSet, a new machine is immediately created to satisfy the specified number of replicas.

https://docs.okd.io/latest/machine_management/deleting-machine.html

Applying autoscaling to an OKD cluster involves deploying a ClusterAutoscaler and then deploying MachineAutoscalers for each Machine type in your cluster.

adjusts the size of cluster to meet its current deployment needs

• has a cluster scope, and is not associated with a particular namespace.
• makes more machines when the cluster running out of resources

adjusts the number of Machines in the MachineSets

• makes more Machines when the cluster runs out of resources
• any changes to the autoscaler resoures (eg.: min, max) applies immediatelly to the machineset

You must deploy a MachineAutoscaler for the ClusterAutoscaler to scale your machines. The ClusterAutoscaler uses the annotations on MachineSets that the MachineAutoscaler sets to determine the resources that it can scale. If you define a ClusterAutoscaler without also defining MachineAutoscalers, the ClusterAutoscaler will never scale your cluster.

Because the ClusterAutoscaler is scoped to the entire cluster, you can make only one ClusterAutoscaler for the cluster.

You need to create a ClusterAutoscaler.yaml file, which shows the parameters and sample values for the ClusterAutoscaler.

oc create -f ClusterAutoscaler.yaml

After you configure the ClusterAutoscaler, you must configure at least one MachineAutoscaler.

The MachineAutoscaler.yaml file shows the parameters and sample values for the MachineAutoscaler.

oc create -f MachineAutoscaler.yaml

oc get machineautoscalers -n openshift-machine-api

oc edit machineautoscalers <autosclaer_name> -n openshift-machine-api

oc describe machineautoscalers <autosclaer_name> -n openshift-machine-api

https://docs.okd.io/latest/machine_management/applying-autoscaling.html