5.3. Configuring the cluster autoscaler
First, deploy the cluster autoscaler to manage automatic resource scaling in your OpenShift Container Platform cluster.
Because the cluster autoscaler is scoped to the entire cluster, you can make only one cluster autoscaler for the cluster.
5.3.1. ClusterAutoscaler resource definition
This ClusterAutoscaler resource definition shows the parameters and sample values for the cluster autoscaler.
apiVersion: "autoscaling.openshift.io/v1" kind: "ClusterAutoscaler" metadata: name: "default" spec: podPriorityThreshold: -10 1 resourceLimits: maxNodesTotal: 24 2 cores: min: 8 3 max: 128 4 memory: min: 4 5 max: 256 6 gpus: - type: nvidia.com/gpu 7 min: 0 8 max: 16 9 - type: amd.com/gpu 10 min: 0 11 max: 4 12 scaleDown: 13 enabled: true 14 delayAfterAdd: 10m 15 delayAfterDelete: 5m 16 delayAfterFailure: 30s 17 unneededTime: 5m 18
- 1
- Specify the priority that a pod must exceed to cause the cluster autoscaler to deploy additional nodes. Enter a 32-bit integer value. The
podPriorityThresholdvalue is compared to the value of thePriorityClassthat you assign to each pod. - 2
- Specify the maximum number of nodes to deploy. This value is the total number of machines that are deployed in your cluster, not just the ones that the autoscaler controls. Ensure that this value is large enough to account for all of your control plane and compute machines and the total number of replicas that you specify in your
MachineAutoscalerresources. - 3
- Specify the minimum number of cores to deploy.
- 4
- Specify the maximum number of cores to deploy.
- 5
- Specify the minimum amount of memory, in GiB, in the cluster.
- 6
- Specify the maximum amount of memory, in GiB, in the cluster.
- 7 10
- Optionally, specify the type of GPU node to deploy. Only
nvidia.com/gpuandamd.com/gpuare valid types. - 8 11
- Specify the minimum number of GPUs to deploy.
- 9 12
- Specify the maximum number of GPUs to deploy.
- 13
- In this section, you can specify the period to wait for each action by using any valid ParseDuration interval, including
ns,us,ms,s,m, andh. - 14
- Specify whether the cluster autoscaler can remove unnecessary nodes.
- 15
- Optionally, specify the period to wait before deleting a node after a node has recently been added. If you do not specify a value, the default value of
10mis used. - 16
- Specify the period to wait before deleting a node after a node has recently been deleted. If you do not specify a value, the default value of
10sis used. - 17
- Specify the period to wait before deleting a node after a scale down failure occurred. If you do not specify a value, the default value of
3mis used. - 18
- Specify the period before an unnecessary node is eligible for deletion. If you do not specify a value, the default value of
10mis used.
When performing a scaling operation, the cluster autoscaler remains within the ranges set in the ClusterAutoscaler resource definition, such as the minimum and maximum number of cores to deploy or the amount of memory in the cluster. However, the cluster autoscaler does not correct the current values in your cluster to be within those ranges.
5.3.2. Deploying the cluster autoscaler
To deploy the cluster autoscaler, you create an instance of the ClusterAutoscaler resource.
Procedure
-
Create a YAML file for the
ClusterAutoscalerresource that contains the customized resource definition. Create the resource in the cluster:
$ oc create -f <filename>.yaml 1- 1
<filename>is the name of the resource file that you customized.
