OpenShift Container Platform

Configure the maximum number of pods per node

You can use the podsPerCore and maxPods parameters in a kubelet configuration to control the maximum number of pods that can be scheduled to a node. If you use both options, the lower of the two limits the number of pods on a node. Setting an appropriate maximum can help ensure your nodes run efficiently.

For example, if podsPerCore is set to 10 on a node with 4 processor cores, the maximum number of pods allowed on the node will be 40.

Prerequisites

You have the label associated with the static MachineConfigPool CRD for the type of node you want to configure.

Procedure

Create a custom resource (CR) for your configuration change.
Sample configuration for a max-pods CR
```
apiVersion: machineconfiguration.openshift.io/v1
kind: KubeletConfig
metadata:
  name: set-max-pods
spec:
  machineConfigPoolSelector:
    matchLabels:
      pools.operator.machineconfiguration.openshift.io/worker: ""
  kubeletConfig:
    podsPerCore: 10
    maxPods: 250
#...
```
where:

metadata.name

Specifies a name for the CR.

spec.machineConfigPoolSelector.matchLabels

Specifies the label from the machine config pool.

spec.kubeletConfig.podsPerCore

Specifies the number of pods the node can run based on the number of processor cores on the node.

spec.kubeletConfig.maxPods

Specifies the number of pods the node can run to a fixed value, regardless of the properties of the node.

Setting podsPerCore to 0 disables this limit.

In the above example, the default value for podsPerCore is 10 and the default value for maxPods is 250. This means that unless the node has 25 cores or more, by default, podsPerCore will be the limiting factor.
Run the following command to create the CR:
```
$ oc create -f <file_name>.yaml
```

Verification

List the MachineConfigPool CRDs to check if the change is applied. The UPDATING column reports True if the change is picked up by the Machine Config Controller:

$ oc get machineconfigpools

Example output

NAME     CONFIG                        UPDATED   UPDATING   DEGRADED
master   master-9cc2c72f205e103bb534   False     False      False
worker   worker-8cecd1236b33ee3f8a5e   False     True       False

After the change is complete, the UPDATED column reports True.

$ oc get machineconfigpools

Example output

NAME     CONFIG                        UPDATED   UPDATING   DEGRADED
master   master-9cc2c72f205e103bb534   False     True       False
worker   worker-8cecd1236b33ee3f8a5e   True      False      False