Eks

To add other roles to access EKS cluster other than the one who created it, add the user/role as master in the cluster.

apiVersion: v1
kind: ConfigMap
metadata:
  name: aws-auth
  namespace: kube-system
data:
  mapRoles: |
    - rolearn: arn:aws:iam::428561211631:role/PHC-IT-EKS-NG-01-NodeInstanceRole-19W8Q1BTI0P3B
      username: system:node:{{EC2PrivateDNSName}}
      groups:
        - system:bootstrappers
        - system:nodes
    - rolearn: arn:aws:iam::428561211631:role/ROLE-PHC-POC-SB-03-SB-AWSADM
      username: ROLE-PHC-POC-SB-03-SB-AWSADM
      groups:
        - system:masters

A user or role can be directly given permission to administrator the cluster by editing the configmap:
kubectl edit configmap -n kube-system aws-auth