I would like to propose and enhancement to the AWS S3 endpoint to support custom credential providers.
Currently the S3 endpoint support static long living key pair option, EC2 IAM role option or a STS based option.
All of these options are not part of the security best practices at our enterprise.
We use Hashicorp Vault to provision temporary, short lived AWS credentials. The AWS S3 endpoint should fetching these temporary credentials from valut and should also support refreshing the credentials seamlessly. The temporary credentials have a session token along with the access key and secret key.