[Docs]: Change IRSA example to include only CA fingerprint

[pnieweglowski]

Documentation Link

website/docs/r/eks_cluster.html.markdown

Description

Pull request #26523 changed in example document, usage of resource aws_iam_openid_connect_provider, attribute thumbprint_list to contain list off all fingerprints from cert chain gathered from IdP.
As number of oidc's thumbprints in AWS is limited to 5, and cert chains with number of certificates exceeding 3 are quite common, it is easy to touch the hard limit of the resource.
In AWS IAM OIDC docs, there is a statement
IAM requires the thumbprint for the top intermediate certificate authority (CA) that signed the certificate used by the external identity provider (IdP)
so only first fingerprint from data.tls_certificate should be used.

References

https://docs.aws.amazon.com/IAM/latest/UserGuide/id_roles_providers_create_oidc_verify-thumbprint.html

Would you like to implement a fix?

None

[github-actions]

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[justinretzolk]

Hey @pnieweglowski 👋 Thank you for taking the time to raise this, and for the helpful link! I've opened a pull request to update the documentation as needed.

[github-actions]

This functionality has been released in v5.12.0 of the Terraform AWS Provider. Please see the Terraform documentation on provider versioning or reach out if you need any assistance upgrading.

For further feature requests or bug reports with this functionality, please create a new GitHub issue following the template. Thank you!

[github-actions]

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