Add SSO docs for Amazon Cognito

[csantanapr]

Summary

Add SSO docs for Amazon Cognito

Motivation

I wanted to use Amazon Cognito and was not able to find docs 😢

Proposal

I was able to figure it out and would like to contribute this to the docs Here is my work:

• https://github.com/aws-ia/terraform-aws-eks-blueprints/blob/argo-multi-cluster/examples/gitops/argocd-multi-cluster/README.md#optional-argocd-sso-login-with-amazon-cognito
• https://github.com/aws-ia/terraform-aws-eks-blueprints/blob/argo-multi-cluster/examples/gitops/argocd-multi-cluster/hub-cluster/helm-argocd/values.yaml

[nicl-dev]

Have you, or anyone else reading this, by any chance managed to make this work with the AWS IAM Identity Center? I see tons of people struggling with it but haven't seen a single working example of it, which is really frustrating.

[YoonJihwan39]

Thank you for guide. I followed your guide and succeeded to login with cognito. But I got an error when sign out, due to no client id and logout uri. So I edited logoutURL as follow: logoutURL: https://{client-app-name}.auth.{aws-region}.amazoncognito.com/logout?client_id={app client ID}&logout_uri=https://${your-ARGOCD-fqdn}/logout