
Amazon EKS Blueprints automates custom networking configuration with VPC CNI to solve IPv4 exhaustion by allocating Pod IPs from secondary VPC CIDR ranges instead of primary subnets.


<div><p>This article explains how to automate custom networking configuration in Amazon EKS to solve IPv4 address exhaustion using AWS CDK EKS Blueprints.</p><ul><li>VPC CNI plugin assigns Pod IPs from primary subnet, causing IPv4 exhaustion at scale</li><li>Custom networking allocates Pod IPs from secondary VPC CIDR ranges instead</li><li>EKS Blueprints pattern automates complex setup of secondary subnets and ENIConfig resources</li><li>Pattern deploys EKS cluster with VPC CNI add-on pre-configured for custom networking</li><li>Prefix delegation increases max Pods from 20 to 110 on m5.large instances</li><li>ENIConfig custom resources created per availability zone for Pod subnet assignment</li><li>Worker nodes still use primary CIDR; only Pods use secondary CIDR ranges</li><li>Blueprints enable enterprise-wide IaC deployment across multiple environments and accounts</li></ul><p>This solution simplifies IPv4 exhaustion mitigation by automating custom networking setup at cluster provisioning time, eliminating manual configuration and node draining.</p></div>


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