Terraform Sentinel: Overview and Business Use Cases

Terraform Sentinel is a policy-as-code framework used to enforce compliance and governance within Terraform, allowing organizations to define and implement policies to control the provisioning of infrastructure. Sentinel is integrated into HashiCorp products like Terraform Enterprise and Terraform Cloud, providing fine-grained, logic-based policy controls.

Key Features of Terraform Sentinel:

1. Policy-as-Code: Write policies using a high-level language, allowing version control and easier updates.
2. Fine-Grained Control: Define detailed policies to enforce compliance with organizational standards and best practices.
3. Extensibility: Create custom functions and modules to extend Sentinel’s capabilities.
4. Integration with Terraform: Apply policies during the Terraform plan and apply phases to ensure infrastructure meets defined policies before deployment.

Business Use Cases:

1. Compliance and Governance: Ensure infrastructure deployments adhere to industry standards and regulatory requirements.
2. Cost Management: Enforce policies to control and optimize cloud resource usage, preventing cost overruns.
3. Security: Implement policies to enforce security best practices, such as restricting open security groups or enforcing encryption.
4. Operational Best Practices: Enforce organizational standards for infrastructure deployment, ensuring consistency and reliability.

How to Integrate Sentinel with Terraform

To integrate Sentinel with Terraform, follow these steps:

1. Define Sentinel Policies:
   • Write Sentinel policies in the Sentinel policy language.
   • Policies are written in .sentinel files.
2. Test Policies Locally:
   • Use the Sentinel CLI to test policies against Terraform plans.
   • Example command: sentinel test policy.sentinel
3. Upload Policies to Terraform Cloud or Enterprise:
   • Add policies to your Terraform Cloud or Terraform Enterprise workspace.
   • Navigate to the workspace settings and upload your policy files.
4. Enforce Policies in Terraform Workflow:
   • Configure the workspace to enforce policies during the plan and apply phases.
   • Policies can be set to advisory or mandatory enforcement.

Example Sentinel Policy

Overview of Terraform Sentinel

Defining Policies – Sentinel – HCP Terraform | Terraform | HashiCorp Developer

How to Manage Policyies to define on Terraform code

Using Hashicorp Sentinel to implement Policy-as-Code within your Terraform Provisioning workflow | by Bruce Cutler | Slalom Technology | Medium

Manage Policies and Policy Sets – HCP Terraform | Terraform | HashiCorp Developer