This is a tool for creating an EKS cluster with custom networking. This is based on the AWS documentation - Custom Networking for pods.
Unlike the documentation, for higher customization and convenience, this tool utilizes eksctl to create the cluster, assign appropriate VPC CIDR, recycle nodes and many cluster operation for convenience. It uses AWS CLI to create the ENIConfig custom resources.
In EKS Clusters, the vpc cni plugin will assign pods an ip address selected from the primary subnet.
The primary subnet is the subnet CIDR that the primary ENI is attached to, one that is associated with VPC by default during cluster create operation. The maximum number of Pods you can run on a node is determined by the number of IP addresses available in the primary subnet.
In Custom Networking, we enable to VPC CNI to assign Pods an IP address from a secondary subnet. This allows you to run more Pods on a node. Custom networking support supports ENIConfig custom resource. The ENIConfig includes an alternate subnet CIDR range (carved from a secondary VPC CIDR), along with the security group(s) that the Pods will belong to. When custom networking is enabled, the VPC CNI creates secondary ENIs in the subnet defined under ENIConfig. The CNI assigns Pods an IP addresses from a CIDR range defined in a ENIConfig CRD.
This tool will create a cluster with custom networking enabled. It will create two subnets in two different AZs. It will create two ENIConfig custom resources, one for each subnet. It will then recycle the nodes to enable custom networking.
