Allow aws credentials to be passed into exec

[heruscode]

what

• Add optional envs for AWS credentials when running kube_exec_auth method.

why

• I have a case where all of my AWS changes are made with temporary AWS credentials, generated by HashiCorp Vault in .tf code. In my Terraform runtime environment i have 0 AWS credentials, so aws eks get-token fails. I need a way to pass credentials into kube_exec_auth.

references

• This is a implementation example, we can generate AWS credentials using a Vault data_source and pass it into the module.

[Nuru]

/test terratest

[Nuru]

@heruscode Thank you for your contribution. We appreciate the effort.

Unfortunately, as written, this PR will likely break exec_auth for anyone who is using environment variables to pass AWS credentials.

For your use case, use the default settings where kube_data_auth_enabled is true. The data_auth method is the "right way" and the one we are committed to supporting. The other methods are hacks to work around issues with the Kubernetes provider and the way Terraform handles providers. We are not going to address issues like yours with the other authentication methods.