ABOUTME: Terraform/Terragrunt IaC patterns, modules, state management
ABOUTME: Best practices for HCL, DRY configs, security scanning
Terraform & Terragrunt
What's New (2025-2026)
| Feature | Description |
|---|---|
| Import blocks | Declarative imports without CLI |
| Check blocks | Continuous validation assertions |
| Moved blocks | Refactor without state surgery |
| Ephemeral (OpenTofu) | Resources not stored in state |
OpenTofu: CNCF fork, 100% compatible, recommended for new projects (BSL licensing).
Quick Reference
terraform init|plan|apply|destroy
terragrunt run-all apply
terraform fmt -recursive && terraform validate
terraform state list|show|rm|mv <resource>See: _AST_GREP.md (sg patterns for HCL)
Project Structure
Simple: main.tf, variables.tf, outputs.tf, versions.tf
Multi-env:
terraform/
├── modules/{vpc,eks}/
└── environments/{dev,staging,prod}/TF 1.5+ Blocks
import { to = aws_instance.web; id = "i-1234567890abcdef0" }
moved { from = aws_instance.web; to = module.web.aws_instance.main }
check "health" {
data "http" "api" { url = "https://api.example.com/health" }
assert { condition = data.http.api.status_code == 200; error_message = "API down" }
}Terragrunt
Benefits: DRY configs, multi-env mgmt, dependency ordering, auto backend config
Structure
infrastructure/
├── terragrunt.hcl # Root
├── _envcommon/{vpc,eks}.hcl
├── {dev,staging,prod}/
│ └── {region}/{vpc,eks}/terragrunt.hclDependencies
dependency "vpc" { config_path = "../vpc" }
inputs = { vpc_id = dependency.vpc.outputs.vpc_id }State Management
Split by: env, region, component, blast radius
backend "s3" { bucket = "my-state"; key = "prod/terraform.tfstate"; encrypt = true; dynamodb_table = "terraform-locks" }Best Practices
| DO | DON'T |
|---|---|
| Modules for reusable components | Hardcode values |
| Version modules | Commit.tfstate to git |
sensitive = true for secrets | Share state across envs |
Testing & Security
Pipeline: fmt/validate → TFLint → Checkov/Trivy → Infracost
terraform fmt -check -recursive && terraform validate
tflint --recursive
checkov -d . --framework terraform --compact
infracost breakdown --path .Code Review Checklist
Security: No hardcoded secrets, encrypted state, locking enabled, least-privilege IAM, Checkov passes
Structure: Versioned modules, validated variables, consistent naming
Resources
| Tool | Purpose |
|---|---|
| TFLint | Linter |
| Checkov | Security |
| Infracost | Cost estimation |
Docs: Terraform, OpenTofu, Terragrunt