When you create an Amazon EKS cluster, it is by default configured as an OpenID Connect (OIDC) identity provider (IdP). This means that it can be used to provide federated access to AWS resources, just like Google, Microsoft, and Facebook IdPs.
AWS also supports IdPs compatible with OIDC to establish trust relationships to access AWS accounts. This means that you can use your EKS OIDC IdP to access AWS services using the IAM identity federation.
NOTE: We have already created the Amazon EKS cluster
Link: AWS — Provision EKS Cluster Using Terraform Resources
Link: Provision Amazon EKS Cluster Using Terraform Modules
What is an identity provider in AWS?
An identity provider (IdP) is a trusted entity that provides authentication services to users. In AWS, an IdP can be used to manage user identities outside of AWS and to federate access to AWS resources.