2.15. Configuring the maximum number of pods per node

Prerequisites

1. Obtain the label associated with the static MachineConfigPool CRD for the type of node you want to configure. Perform one of the following steps:

   1. View the machine config pool:

      $ oc describe machineconfigpool <name>

      For example:

      $ oc describe machineconfigpool worker

      Example output

      apiVersion: machineconfiguration.openshift.io/v1
      kind: MachineConfigPool
      metadata:
        creationTimestamp: 2019-02-08T14:52:39Z
        generation: 1
        labels:
          custom-kubelet: small-pods 1

      1

      If a label has been added it appears under labels.

   2. If the label is not present, add a key/value pair:

      $ oc label machineconfigpool worker custom-kubelet=small-pods

Procedure

1. 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 1
   spec:
     machineConfigPoolSelector:
       matchLabels:
         custom-kubelet: small-pods 2
     kubeletConfig:
       podsPerCore: 10 3
       maxPods: 250 4

   1

   Assign a name to CR.

   2

   Specify the label to apply the configuration change.

   3

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

   4

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

   注意

   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.

2. List the MachineConfigPool CRDs to see 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

   Once 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