Override Pod density for a node pool

This document describes how to specify Pod density for individual node pools in your cluster, overriding the cluster-wide setting. Although node-level configurations typically apply to the entire cluster, you can configure Pod density on a specific node pool. Overriding the Pod density for specific node pools can improve resource efficiency. This capability is useful for specialized node pools, such as nodes with GPUs, where specific workload requirements or efficient IP address allocation necessitate a different value for maximum Pods per node.

The capability to override the cluster-wide Pod density setting is available for clusters at version 1.33 and higher.

Before you begin

The capability to specify Pod density for node pools is only available for clusters with one of the following network configurations:

• Flat IPv4 static mode networking
• IPv4/IPv6 dual-stack networking

Configure Pod density for a node pool

Configure Pod density within the NodePool specification to override cluster-level settings. This configuration is optional. The system derives the size of the CIDR range assigned to the node from the maximum Pods per node parameter.

The maxPodsPerNode configuration is immutable after node pool creation. The system validates the maxPodsPerNode setting to ensure sufficient IP addresses for nodes in the node pool. This validation uses strict label binding, where a ClusterCIDRConfig binds to a node pool using a node selector. You can skip this validation by setting the baremetal.cluster.gke.io/skip-pod-cidr-size-check annotation on the Cluster CR or at the NodePool level.

1. Create a ClusterCIDRConfig resource.

   This resource binds to a specific NodePool using a node selector.

   apiVersion: networking.gke.io/v1alpha1
   kind: ClusterCIDRConfig
   metadata:
     name: my-nodepool-cidr-config
   spec:
     nodeSelector:
       matchLabels:
         baremetal.cluster.gke.io/node-pool: NODE_POOL_NAME
     # ... other CIDR config fields (e.g., podCIDR, perNodeMaskSize)
   

   Replace NODE_POOL_NAME with the name of your NodePool.

2. Create the node pool with overridden Pod density.

   Specify the nodeConfigOverride field in the NodePool definition. This field contains the podDensity configuration.

   apiVersion: baremetal.cluster.gke.io/v1
   kind: NodePool
   metadata:
     name: NODEPOOL_NAME
     namespace: CLUSTER_NAMESPACE
   spec:
     cluster: CLUSTER_NAME
     nodeConfigOverride:
       podDensity:
         maxPodsPerNode: MAX_PODS_PER_NODE
     # ... other NodePoolSpec fields like nodeCount, taints, labels etc. ...
   

   Replace the following:

   • NODEPOOL_NAME: the name of the node pool resource whose maximum Pods per node value you are overriding.

   • CLUSTER_NAMESPACE: the namespace of the cluster where the node pool resides.

   • CLUSTER_NAME: the name of the cluster where you override node pool settings.

   • MAX_PODS_PER_NODE: the maximum number of Pods you can run on a single node in the specified node pool.

What's next

• Learn about the differences between the flat mode and island mode network models.
• Learn how to Implement flat IPv4 mode network model.
• Learn how to create a cluster with IPv4/IPv6 dual-stack networking.
• Learn about the bundled NVIDIA GPU Operator.
• Understand how Pod CIDR blocks, the number of nodes, and the Pod density correlate.