Red Hat OpenShift Container Platform

Configure machine autoscalers

After you deploy the cluster autoscaler, deploy MachineAutoscaler resources that reference the compute machine sets that are used to scale the cluster.

You must deploy at least one MachineAutoscaler resource after you deploy the ClusterAutoscaler resource.

You must configure separate resources for each compute machine set. Remember that compute machine sets are different in each region, so consider whether you want to enable machine scaling in multiple regions. The compute machine set that you scale must have at least one machine in it.

Machine autoscaler resource definition

This MachineAutoscaler resource definition shows the parameters and sample values for the machine autoscaler.

apiVersion: "autoscaling.openshift.io/v1beta1"
kind: "MachineAutoscaler"
metadata:
  name: "worker-us-east-1a"
  namespace: "openshift-machine-api"
spec:
  minReplicas: 1
  maxReplicas: 12
  scaleTargetRef:
    apiVersion: machine.openshift.io/v1beta1
    kind: MachineSet
    name: worker-us-east-1a

where:

<name>

Specify the machine autoscaler name. To make it easier to identify which compute machine set this machine autoscaler scales, specify or include the name of the compute machine set to scale. The compute machine set name takes the following form: <clusterid>-<machineset>-<region>.

<minReplicas>

Specify the minimum number machines of the specified type that must remain in the specified zone after the cluster autoscaler initiates cluster scaling. If running in AWS, Google Cloud, Azure, RHOSP, or vSphere, this value can be set to 0. For other providers, do not set this value to 0.

You can save on costs by setting this value to 0 for use cases such as running expensive or limited-usage hardware that is used for specialized workloads, or by scaling a compute machine set with extra large machines. The cluster autoscaler scales the compute machine set down to zero if the machines are not in use.

Do not set the spec.minReplicas value to 0 for the three compute machine sets that are created during the Red Hat OpenShift Container Platform installation process for an installer provisioned infrastructure.

<maxReplicas>

Specify the maximum number machines of the specified type that the cluster autoscaler can deploy in the specified zone after it initiates cluster scaling. Ensure that the maxNodesTotal value in the ClusterAutoscaler resource definition is large enough to allow the machine autoscaler to deploy this number of machines.

<scaleTargetRef>

In this section, provide values that describe the existing compute machine set to scale.

<kind>

The kind parameter value is always MachineSet.

<name>

The name value must match the name of an existing compute machine set, as shown in the metadata.name parameter value.