High Available Vault cluster on AWS ECS Fargate

I need some guidance with deploying a High Available Vault cluster in AWS ECS Cluster with Fargate. I am able to deploy a single vault server using terraform for the Infrastructure and Vault setup on AWS ECS with Fargate. Ultimately, I need to be able to run more than one ECS Fargate Vault instance within a Vault cluster and when a new Vault instance is added the instance will automatically join the vault cluster. Additionally, I am using dynamodb as the storage backend and AWS KMS for auto unsealing. I am unable to find any documentation on how to accomplish this setup. Any assistance and/or suggestion would be greatly appreciation.