Terraformv1.12

18 March 2026

Terraform 1.12 — Stacks, Ephemeral Values, and OPA Policy Integration

Terraform 1.12 ships three long-requested features: Stacks (composable multi-environment configurations), ephemeral values (secrets that never touch state), and native OPA policy enforcement — closing the gap with enterprise tooling without requiring Terraform Cloud.

• 1Stacks GA — new .tfstack.hcl and .tfdeploy.hcl file types let you compose root modules and deploy them across multiple environments declaratively
• 2Ephemeral values — mark resources and outputs as ephemeral to prevent them from appearing in state files or plan output; essential for credentials and tokens
• 3Native OPA policy integration — terraform plan can evaluate .rego policies without external CI wrappers
• 4Provider-defined functions — providers can expose custom functions callable in HCL expressions (e.g., cidrsubnet from a network provider)
• 5Test framework improvements — terraform test now supports mocking provider responses for faster, offline unit tests
• 6Improved moved and removed blocks — supports cross-module resource transfers without destroy/recreate
• 7OpenTelemetry traces for terraform plan and apply — correlate infrastructure changes with deployment pipelines