terraform

Terraform / Infrastructure as Code

Purpose: Best practices for provisioning cloud resources with Terraform, covering code style, file layout, naming, state management, modules, security, and testing.

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When to Use This Skill

• Writing or editing .tf or .tfvars files
• Creating reusable Terraform modules
• Managing remote state backends
• Securing infrastructure definitions
• Running Terratest or terraform validate / terraform plan

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Decision Tree

Terraform Decision
+-- New infrastructure project?
|   +-- Azure only? -> Consider Bicep as alternative
|   +-- Multi-cloud or AWS/GCP? -> Use Terraform
|   +-- Existing Terraform codebase? -> Use Terraform
+-- Structuring code?
|   +-- Single environment? -> One root module with terraform.tfvars
|   +-- Multiple environments? -> Workspaces or separate root dirs per env
|   +-- Shared patterns? -> Extract reusable modules/ with versioning
+-- Managing state?
|   +-- Team project? -> Remote backend with locking (S3/Azure Storage/GCS)
|   +-- Solo developer? -> Remote backend still recommended
|   +-- Never -> Local .tfstate in production
+-- Validating changes?
|   +-- Syntax? -> terraform validate
|   +-- Drift detection? -> terraform plan
|   +-- Integration tests? -> Terratest (Go)

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Code Style

• Use Terraform 1.5+ features (import blocks, check blocks, moved blocks)
• Maximum line length: 120 characters
• Use terraform fmt for formatting (enforced via pre-commit)
• Use tflint for linting

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File Organization

infra/
+-- main.tf            # Provider config, data sources
+-- variables.tf       # Input variable declarations
+-- outputs.tf         # Output value declarations
+-- terraform.tfvars   # Variable values (gitignored in prod)
+-- locals.tf          # Local values and computed expressions
+-- versions.tf        # Required providers and versions
-- modules/
    -- networking/     # Reusable module
        +-- main.tf
        +-- variables.tf
        -- outputs.tf