How do I use custom user data with Amazon Linux 2023 EKS nodes?

Short description

Amazon Linux 2023 uses the nodeadm node initialization process that uses a YAML configuration schema. For more information, see the Before upgrading to AL2023 section in the Amazon EKS-optimized Amazon Linux 2023 AMIs now available.

Resolution

Add the minimum required parameters to user data in the following format:

MIME-Version: 1.0
Content-Type: multipart/mixed; boundary="//"

--//
Content-Type: application/node.eks.aws

---
apiVersion: node.eks.aws/v1alpha1
kind: NodeConfig
spec:
  cluster:
    apiServerEndpoint: https://example.com
    certificateAuthority: Y2VydGlmaWNhdGVBdXRob3JpdHk=
    cidr: 10.100.0.0/16
    name: my-cluster

--//--

Modify the kubelet or containerd components in the following format:

MIME-Version: 1.0
Content-Type: multipart/mixed; boundary="==MYBOUNDARY=="

--==MYBOUNDARY==
Content-Type: application/node.eks.aws

---
apiVersion: node.eks.aws/v1alpha1
kind: NodeConfig
spec:
  cluster:
    name: my-cluster
    apiServerEndpoint: https://example.com
    certificateAuthority: Y2VydGlmaWNhdGVBdXRob3JpdHk=
    cidr: 10.100.0.0/16
  kubelet:
    config:
      maxPods: 17
      clusterDNS:
      - 10.100.0.10
    flags:
    - "--node-labels=eks.amazonaws.com/nodegroup-image=ami-0cc04929616d2c6ba,eks.amazonaws.com/capacityType=ON_DEMAND,eks.amazonaws.com/nodegroup=al23"
   containerd: {}
  instance:
    localStorage: {}
    
--==MYBOUNDARY==--

Pass custom scripts or commands in the following format:

MIME-Version: 1.0
Content-Type: multipart/mixed; boundary="//"

--//
Content-Type: application/node.eks.aws

apiVersion: node.eks.aws/v1alpha1
kind: NodeConfig
spec:
  cluster:
    name: my-cluster
    apiServerEndpoint: https://example.com
    certificateAuthority: Y2VydGlmaWNhdGVBdXRob3JpdHk=
    cidr: 10.100.0.0/16
    
--//
Content-Type: text/x-shellscript; charset="us-ascii"

#!/bin/bash
echo "Hello AL2023!"
--//

Related information

Amazon EKS AMI API reference