How can Terraform Enterprise enforce security controls for new AWS S3 buckets to be private and encrypted at rest?

The implementation of security controls in Terraform Enterprise, specifically for new AWS S3 buckets to ensure they are private and encrypted at rest, is effectively managed through the use of a Sentinel policy, which runs before every apply.

Sentinel is a policy-as-code framework that allows you to define and enforce rules for infrastructure configurations. By creating a Sentinel policy, you can set the required conditions that S3 buckets must meet—such as being private and having server-side encryption enabled. These policies are evaluated whenever a change is proposed in Terraform, and this pre-apply check ensures that any directed rule is adhered to before modifications occur, thereby providing a robust security mechanism.

Using IAM roles to manage permissions or configuring S3 settings directly in the AWS console does not inherently enforce the specific conditions on bucket properties or ensure compliance with security standards across all Terraform deployments. Similarly, using environment variables for configuration management does not provide the same level of enforcement and compliance verification as a dedicated policy would. Hence, the strength of using Sentinel lies in its ability to enforce compliance in a centralized and automated way.