Terraform Skill

Terraform Skill for Claude

Overview

This public intake copy packages plugins/antigravity-awesome-skills-claude/skills/terraform-skill from https://github.com/sickn33/antigravity-awesome-skills into the native Omni Skills editorial shape without hiding its origin.

Use it when the operator needs the upstream workflow, support files, and repository context to stay intact while the public validator and private enhancer continue their normal downstream flow.

This intake keeps the copied upstream files intact and uses the external_source block in metadata.json plus ORIGIN.md as the provenance anchor for review.

Terraform Skill for Claude Comprehensive Terraform and OpenTofu guidance covering testing, modules, CI/CD, and production patterns. Based on terraform-best-practices.com and enterprise experience.

Imported source sections that did not map cleanly to the public headings are still preserved below or in the support files. Notable imported sections: Testing Strategy Framework, Code Structure Standards, Locals for Dependency Management, Module Development, CI/CD Integration, Security & Compliance.

When to Use This Skill

Use this section as the trigger filter. It should make the activation boundary explicit before the operator loads files, runs commands, or opens a pull request.

• Creating new Terraform or OpenTofu configurations or modules
• Setting up testing infrastructure for IaC code
• Deciding between testing approaches (validate, plan, frameworks)
• Structuring multi-environment deployments
• Implementing CI/CD for infrastructure-as-code
• Reviewing or refactoring existing Terraform/OpenTofu projects

Operating Table

Workflow

This workflow is intentionally editorial and operational at the same time. It keeps the imported source useful to the operator while still satisfying the public intake standards that feed the downstream enhancer flow.

1. Confirm the user goal, the scope of the imported workflow, and whether this skill is still the right router for the task.
2. Read the overview and provenance files before loading any copied upstream support files.
3. Load only the references, examples, prompts, or scripts that materially change the outcome for the current request.
4. Execute the upstream workflow while keeping provenance and source boundaries explicit in the working notes.
5. Validate the result against the upstream expectations and the evidence you can point to in the copied files.
6. Escalate or hand off to a related skill when the work moves out of this imported workflow's center of gravity.
7. Before merge or closure, record what was used, what changed, and what the reviewer still needs to verify.

Imported Workflow Notes

Imported: Testing Strategy Framework

Decision Matrix: Which Testing Approach?

Testing Pyramid for Infrastructure

        /\
       /  \          End-to-End Tests (Expensive)
      /____\         - Full environment deployment
     /      \        - Production-like setup
    /________\
   /          \      Integration Tests (Moderate)
  /____________\     - Module testing in isolation
 /              \    - Real resources in test account
/________________\   Static Analysis (Cheap)
                     - validate, fmt, lint
                     - Security scanning

Native Test Best Practices (1.6+)

Before generating test code:

1. Validate schemas with Terraform MCP:

   Search provider docs → Get resource schema → Identify block types
   

2. Choose correct command mode:

   • command = plan - Fast, for input validation
   • command = apply - Required for computed values and set-type blocks

3. Handle set-type blocks correctly:

   • Cannot index with [0]
   • Use for expressions to iterate
   • Or use command = apply to materialize

Common patterns:

• S3 encryption rules: set (use for expressions)
• Lifecycle transitions: set (use for expressions)
• IAM policy statements: set (use for expressions)

For detailed testing guides, see:

• Testing Frameworks Guide - Deep dive into static analysis, native tests, and Terratest
• Quick Reference - Decision flowchart and command cheat sheet

Examples

Example 1: Ask for the upstream workflow directly

Use @terraform-skill to handle <task>. Start from the copied upstream workflow, load only the files that change the outcome, and keep provenance visible in the answer.

Explanation: This is the safest starting point when the operator needs the imported workflow, but not the entire repository.

Example 2: Ask for a provenance-grounded review

Review @terraform-skill against metadata.json and ORIGIN.md, then explain which copied upstream files you would load first and why.

Explanation: Use this before review or troubleshooting when you need a precise, auditable explanation of origin and file selection.

Example 3: Narrow the copied support files before execution

Use @terraform-skill for <task>. Load only the copied references, examples, or scripts that change the outcome, and name the files explicitly before proceeding.

Explanation: This keeps the skill aligned with progressive disclosure instead of loading the whole copied package by default.

Example 4: Build a reviewer packet

Review @terraform-skill using the copied upstream files plus provenance, then summarize any gaps before merge.

Explanation: This is useful when the PR is waiting for human review and you want a repeatable audit packet.

Best Practices

Treat the generated public skill as a reviewable packaging layer around the upstream repository. The goal is to keep provenance explicit and load only the copied source material that materially improves execution.

• Type - When to Use - Scope
• Resource Module - Single logical group of connected resources - VPC + subnets, Security group + rules
• Infrastructure Module - Collection of resource modules for a purpose - Multiple resource modules in one region/account
• Composition - Complete infrastructure - Spans multiple regions/accounts
• Separate environments (prod, staging) from modules (reusable components)
• Use examples/ as both documentation and integration test fixtures
• Keep modules small and focused (single responsibility)

Imported Operating Notes

Imported: Core Principles

1. Code Structure Philosophy

Module Hierarchy:

Hierarchy: Resource → Resource Module → Infrastructure Module → Composition

Directory Structure:

environments/        # Environment-specific configurations
├── prod/
├── staging/
└── dev/

modules/            # Reusable modules
├── networking/
├── compute/
└── data/

examples/           # Module usage examples (also serve as tests)
├── complete/
└── minimal/

Key principle from terraform-best-practices.com:

• Separate environments (prod, staging) from modules (reusable components)
• Use examples/ as both documentation and integration test fixtures
• Keep modules small and focused (single responsibility)

For detailed module architecture, see: Code Patterns: Module Types & Hierarchy

2. Naming Conventions

Resources:

# Good: Descriptive, contextual
resource "aws_instance" "web_server" { }
resource "aws_s3_bucket" "application_logs" { }

# Good: "this" for singleton resources (only one of that type)
resource "aws_vpc" "this" { }
resource "aws_security_group" "this" { }

# Avoid: Generic names for non-singletons
resource "aws_instance" "main" { }
resource "aws_s3_bucket" "bucket" { }

Singleton Resources:

Use "this" when your module creates only one resource of that type:

✅ DO:

resource "aws_vpc" "this" {}           # Module creates one VPC
resource "aws_security_group" "this" {}  # Module creates one SG

❌ DON'T use "this" for multiple resources:

resource "aws_subnet" "this" {}  # If creating multiple subnets

Use descriptive names when creating multiple resources of the same type.

Variables:

# Prefix with context when needed
var.vpc_cidr_block          # Not just "cidr"
var.database_instance_class # Not just "instance_class"

Files:

• main.tf - Primary resources
• variables.tf - Input variables
• outputs.tf - Output values
• versions.tf - Provider versions
• data.tf - Data sources (optional)

Troubleshooting

Problem: The operator skipped the imported context and answered too generically

Symptoms: The result ignores the upstream workflow in plugins/antigravity-awesome-skills-claude/skills/terraform-skill, fails to mention provenance, or does not use any copied source files at all. Solution: Re-open metadata.json, ORIGIN.md, and the most relevant copied upstream files. Check the external_source block first, then restate the provenance before continuing.

Problem: The imported workflow feels incomplete during review

Symptoms: Reviewers can see the generated SKILL.md, but they cannot quickly tell which references, examples, or scripts matter for the current task. Solution: Point at the exact copied references, examples, scripts, or assets that justify the path you took. If the gap is still real, record it in the PR instead of hiding it.

Problem: The task drifted into a different specialization

Symptoms: The imported skill starts in the right place, but the work turns into debugging, architecture, design, security, or release orchestration that a native skill handles better. Solution: Use the related skills section to hand off deliberately. Keep the imported provenance visible so the next skill inherits the right context instead of starting blind.

Related Skills

• @00-andruia-consultant - Use when the work is better handled by that native specialization after this imported skill establishes context.
• @00-andruia-consultant-v2 - Use when the work is better handled by that native specialization after this imported skill establishes context.
• @10-andruia-skill-smith - Use when the work is better handled by that native specialization after this imported skill establishes context.
• @10-andruia-skill-smith-v2 - Use when the work is better handled by that native specialization after this imported skill establishes context.

Additional Resources

Use this support matrix and the linked files below as the operator packet for this imported skill. They should reflect real copied source material, not generic scaffolding.

Imported Reference Notes

Imported: Code Structure Standards

Resource Block Ordering

Strict ordering for consistency:

1. count or for_each FIRST (blank line after)
2. Other arguments
3. tags as last real argument
4. depends_on after tags (if needed)
5. lifecycle at the very end (if needed)

# ✅ GOOD - Correct ordering
resource "aws_nat_gateway" "this" {
  count = var.create_nat_gateway ? 1 : 0

  allocation_id = aws_eip.this[0].id
  subnet_id     = aws_subnet.public[0].id

  tags = {
    Name = "${var.name}-nat"
  }

  depends_on = [aws_internet_gateway.this]

  lifecycle {
    create_before_destroy = true
  }
}

Variable Block Ordering

1. description (ALWAYS required)
2. type
3. default
4. validation
5. nullable (when setting to false)

variable "environment" {
  description = "Environment name for resource tagging"
  type        = string
  default     = "dev"

  validation {
    condition     = contains(["dev", "staging", "prod"], var.environment)
    error_message = "Environment must be one of: dev, staging, prod."
  }

  nullable = false
}

For complete structure guidelines, see: Code Patterns: Block Ordering & Structure

Imported: Locals for Dependency Management

Use locals to ensure correct resource deletion order:

# Problem: Subnets might be deleted after CIDR blocks, causing errors
# Solution: Use try() in locals to hint deletion order

locals {
  # References secondary CIDR first, falling back to VPC
  # Forces Terraform to delete subnets before CIDR association
  vpc_id = try(
    aws_vpc_ipv4_cidr_block_association.this[0].vpc_id,
    aws_vpc.this.id,
    ""
  )
}

resource "aws_vpc" "this" {
  cidr_block = "10.0.0.0/16"
}

resource "aws_vpc_ipv4_cidr_block_association" "this" {
  count = var.add_secondary_cidr ? 1 : 0

  vpc_id     = aws_vpc.this.id
  cidr_block = "10.1.0.0/16"
}

resource "aws_subnet" "public" {
  vpc_id     = local.vpc_id  # Uses local, not direct reference
  cidr_block = "10.1.0.0/24"
}

Why this matters:

• Prevents deletion errors when destroying infrastructure
• Ensures correct dependency order without explicit depends_on
• Particularly useful for VPC configurations with secondary CIDR blocks

For detailed examples, see: Code Patterns: Locals for Dependency Management

Imported: Module Development

Standard Module Structure

my-module/
├── README.md           # Usage documentation
├── main.tf             # Primary resources
├── variables.tf        # Input variables with descriptions
├── outputs.tf          # Output values
├── versions.tf         # Provider version constraints
├── examples/
│   ├── minimal/        # Minimal working example
│   └── complete/       # Full-featured example
└── tests/              # Test files
    └── module_test.tftest.hcl  # Or .go

Best Practices Summary

Variables:

• ✅ Always include description
• ✅ Use explicit type constraints
• ✅ Provide sensible default values where appropriate
• ✅ Add validation blocks for complex constraints
• ✅ Use sensitive = true for secrets

Outputs:

• ✅ Always include description
• ✅ Mark sensitive outputs with sensitive = true
• ✅ Consider returning objects for related values
• ✅ Document what consumers should do with each output

For detailed module patterns, see:

• Module Patterns Guide - Variable best practices, output design, ✅ DO vs ❌ DON'T patterns
• Quick Reference - Resource naming, variable naming, file organization

Imported: CI/CD Integration

Recommended Workflow Stages

1. Validate - Format check + syntax validation + linting
2. Test - Run automated tests (native or Terratest)
3. Plan - Generate and review execution plan
4. Apply - Execute changes (with approvals for production)

Cost Optimization Strategy

1. Use mocking for PR validation (free)
2. Run integration tests only on main branch (controlled cost)
3. Implement auto-cleanup (prevent orphaned resources)
4. Tag all test resources (track spending)

For complete CI/CD templates, see:

• CI/CD Workflows Guide - GitHub Actions, GitLab CI, Atlantis integration, cost optimization
• Quick Reference - Common CI/CD issues and solutions

Imported: Security & Compliance

Essential Security Checks

# Static security scanning
trivy config .
checkov -d .

Common Issues to Avoid

❌ Don't:

• Store secrets in variables
• Use default VPC
• Skip encryption
• Open security groups to 0.0.0.0/0

✅ Do:

• Use AWS Secrets Manager / Parameter Store
• Create dedicated VPCs
• Enable encryption at rest
• Use least-privilege security groups

For detailed security guidance, see:

• Security & Compliance Guide - Trivy/Checkov integration, secrets management, state file security, compliance testing

Imported: Version Management

Version Constraint Syntax

version = "5.0.0"      # Exact (avoid - inflexible)
version = "~> 5.0"     # Recommended: 5.0.x only
version = ">= 5.0"     # Minimum (risky - breaking changes)

Strategy by Component

Update Workflow

# Lock versions initially
terraform init              # Creates .terraform.lock.hcl

# Update to latest within constraints
terraform init -upgrade     # Updates providers

# Review and test
terraform plan

For detailed version management, see: Code Patterns: Version Management

Imported: Modern Terraform Features (1.0+)

Feature Availability by Version

Quick Examples

# try() - Safe fallbacks (0.13+)
output "sg_id" {
  value = try(aws_security_group.this[0].id, "")
}

# optional() - Optional attributes with defaults (1.3+)
variable "config" {
  type = object({
    name    = string
    timeout = optional(number, 300)  # Default: 300
  })
}

# Cross-variable validation (1.9+)
variable "environment" { type = string }
variable "backup_days" {
  type = number
  validation {
    condition     = var.environment == "prod" ? var.backup_days >= 7 : true
    error_message = "Production requires backup_days >= 7"
  }
}

For complete patterns and examples, see: Code Patterns: Modern Terraform Features

Imported: Version-Specific Guidance

Terraform 1.0-1.5

• Use Terratest for testing
• No native testing framework available
• Focus on static analysis and plan validation

Terraform 1.6+ / OpenTofu 1.6+

• New: Native terraform test / tofu test command
• Consider migrating from external frameworks for simple tests
• Keep Terratest only for complex integration tests

Terraform 1.7+ / OpenTofu 1.7+

• New: Mock providers for unit testing
• Reduce cost by mocking external dependencies
• Use real integration tests for final validation

Terraform vs OpenTofu

Both are fully supported by this skill. For licensing, governance, and feature comparison, see Quick Reference: Terraform vs OpenTofu.

Imported: Detailed Guides

This skill uses progressive disclosure - essential information is in this main file, detailed guides are available when needed:

📚 Reference Files:

• Testing Frameworks - In-depth guide to static analysis, native tests, and Terratest
• Module Patterns - Module structure, variable/output best practices, ✅ DO vs ❌ DON'T patterns
• CI/CD Workflows - GitHub Actions, GitLab CI templates, cost optimization, automated cleanup
• Security & Compliance - Trivy/Checkov integration, secrets management, compliance testing
• Quick Reference - Command cheat sheets, decision flowcharts, troubleshooting guide

How to use: When you need detailed information on a topic, reference the appropriate guide. Claude will load it on demand to provide comprehensive guidance.

Imported: License

This skill is licensed under the Apache License 2.0. See the LICENSE file for full terms.

Copyright © 2026 Anton Babenko

Imported: Limitations

• Use this skill only when the task clearly matches the scope described above.
• Do not treat the output as a substitute for environment-specific validation, testing, or expert review.
• Stop and ask for clarification if required inputs, permissions, safety boundaries, or success criteria are missing.

Source: diegosouzapw/awesome-omni-skills — distributed by TomeVault.