如何使用CDK修改EKS的默认容量实例角色？

import * as eks from '@aws-cdk/aws-eks';
import * as iam from '@aws-cdk/aws-iam';

const stack = new cdk.Stack(app, 'MyStack');
const cluster = new eks.Cluster(stack, 'MyCluster', {
  version: eks.KubernetesVersion.V1_21,
});

const role = new iam.Role(stack, 'MyRole', {
  assumedBy: new iam.ServicePrincipal('ec2.amazonaws.com'),
});

role.addToPolicy(new iam.PolicyStatement({
  actions: ['eks:DescribeCluster'],
  resources: [cluster.clusterArn],
}));

cluster.awsAuth.addRoleMapping(role, {
  groups: ['system:bootstrappers', 'system:nodes'],
  username: 'system:node:{{EC2PrivateDNSName}}',
});