feat: add 61 new skills from VoltAgent repository

- 27 official team skills (Sentry, Trail of Bits, Expo, Hugging Face, etc.) - 34 community skills including context engineering suite - All skills validated and compliant with V4 quality bar - Complete source attribution maintained Skills added: - Official: commit, create-pr, find-bugs, iterate-pr, culture-index, fix-review, sharp-edges, expo-deployment, upgrading-expo, hugging-face-cli, hugging-face-jobs, vercel-deploy-claimable, design-md, using-neon, n8n-*, swiftui-expert-skill, fal-*, deep-research, imagen, readme, screenshots - Community: frontend-slides, linear-claude-skill, skill-rails-upgrade, context-*, multi-agent-patterns, tool-design, evaluation, memory-systems, terraform-skill, and more
2026-01-30 09:15:26 +01:00
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+---
+name: terraform-skill
+description: "Terraform infrastructure as code best practices"
+license: Apache-2.0
+metadata: 
+author: "Anton Babenko"
+version: 1.5.0
+source: "https://github.com/antonbabenko/terraform-skill"
+risk: safe
+---
+# 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.
+
+## When to Use This Skill
+
+**Activate this skill when:**
+- 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
+- Choosing between module patterns or state management approaches
+
+**Don't use this skill for:**
+- Basic Terraform/OpenTofu syntax questions (Claude knows this)
+- Provider-specific API reference (link to docs instead)
+- Cloud platform questions unrelated to Terraform/OpenTofu
+
+## Core Principles
+
+### 1. Code Structure Philosophy
+
+**Module Hierarchy:**
+
+| 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 |
+
+**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](references/code-patterns.md)
+
+### 2. Naming Conventions
+
+**Resources:**
+```hcl
+# 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:
+```hcl
+resource "aws_vpc" "this" {}           # Module creates one VPC
+resource "aws_security_group" "this" {}  # Module creates one SG
+```
+
+❌ DON'T use "this" for multiple resources:
+```hcl
+resource "aws_subnet" "this" {}  # If creating multiple subnets
+```
+
+Use descriptive names when creating multiple resources of the same type.
+
+**Variables:**
+```hcl
+# 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)
+
+## Testing Strategy Framework
+
+### Decision Matrix: Which Testing Approach?
+
+| Your Situation | Recommended Approach | Tools | Cost |
+|----------------|---------------------|-------|------|
+| **Quick syntax check** | Static analysis | `terraform validate`, `fmt` | Free |
+| **Pre-commit validation** | Static + lint | `validate`, `tflint`, `trivy`, `checkov` | Free |
+| **Terraform 1.6+, simple logic** | Native test framework | Built-in `terraform test` | Free-Low |
+| **Pre-1.6, or Go expertise** | Integration testing | Terratest | Low-Med |
+| **Security/compliance focus** | Policy as code | OPA, Sentinel | Free |
+| **Cost-sensitive workflow** | Mock providers (1.7+) | Native tests + mocking | Free |
+| **Multi-cloud, complex** | Full integration | Terratest + real infra | Med-High |
+
+### 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](references/testing-frameworks.md)** - Deep dive into static analysis, native tests, and Terratest
+- **[Quick Reference](references/quick-reference.md#testing-approach-selection)** - Decision flowchart and command cheat sheet
+
+## 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)
+
+```hcl
+# ✅ 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)
+
+```hcl
+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](references/code-patterns.md#block-ordering--structure)
+
+## Count vs For_Each: When to Use Each
+
+### Quick Decision Guide
+
+| Scenario | Use | Why |
+|----------|-----|-----|
+| Boolean condition (create or don't) | `count = condition ? 1 : 0` | Simple on/off toggle |
+| Simple numeric replication | `count = 3` | Fixed number of identical resources |
+| Items may be reordered/removed | `for_each = toset(list)` | Stable resource addresses |
+| Reference by key | `for_each = map` | Named access to resources |
+| Multiple named resources | `for_each` | Better maintainability |
+
+### Common Patterns
+
+**Boolean conditions:**
+```hcl
+# ✅ GOOD - Boolean condition
+resource "aws_nat_gateway" "this" {
+  count = var.create_nat_gateway ? 1 : 0
+  # ...
+}
+```
+
+**Stable addressing with for_each:**
+```hcl
+# ✅ GOOD - Removing "us-east-1b" only affects that subnet
+resource "aws_subnet" "private" {
+  for_each = toset(var.availability_zones)
+
+  availability_zone = each.key
+  # ...
+}
+
+# ❌ BAD - Removing middle AZ recreates all subsequent subnets
+resource "aws_subnet" "private" {
+  count = length(var.availability_zones)
+
+  availability_zone = var.availability_zones[count.index]
+  # ...
+}
+```
+
+**For migration guides and detailed examples, see:** [Code Patterns: Count vs For_Each](references/code-patterns.md#count-vs-for_each-deep-dive)
+
+## Locals for Dependency Management
+
+**Use locals to ensure correct resource deletion order:**
+
+```hcl
+# 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](references/code-patterns.md#locals-for-dependency-management)
+
+## 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](references/module-patterns.md)** - Variable best practices, output design, ✅ DO vs ❌ DON'T patterns
+- **[Quick Reference](references/quick-reference.md#common-patterns)** - Resource naming, variable naming, file organization
+
+## 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](references/ci-cd-workflows.md)** - GitHub Actions, GitLab CI, Atlantis integration, cost optimization
+- **[Quick Reference](references/quick-reference.md#troubleshooting-guide)** - Common CI/CD issues and solutions
+
+## Security & Compliance
+
+### Essential Security Checks
+
+```bash
+# 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](references/security-compliance.md)** - Trivy/Checkov integration, secrets management, state file security, compliance testing
+
+## Version Management
+
+### Version Constraint Syntax
+
+```hcl
+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
+
+| Component | Strategy | Example |
+|-----------|----------|---------|
+| **Terraform** | Pin minor version | `required_version = "~> 1.9"` |
+| **Providers** | Pin major version | `version = "~> 5.0"` |
+| **Modules (prod)** | Pin exact version | `version = "5.1.2"` |
+| **Modules (dev)** | Allow patch updates | `version = "~> 5.1"` |
+
+### Update Workflow
+
+```bash
+# 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](references/code-patterns.md#version-management)
+
+## Modern Terraform Features (1.0+)
+
+### Feature Availability by Version
+
+| Feature | Version | Use Case |
+|---------|---------|----------|
+| `try()` function | 0.13+ | Safe fallbacks, replaces `element(concat())` |
+| `nullable = false` | 1.1+ | Prevent null values in variables |
+| `moved` blocks | 1.1+ | Refactor without destroy/recreate |
+| `optional()` with defaults | 1.3+ | Optional object attributes |
+| Native testing | 1.6+ | Built-in test framework |
+| Mock providers | 1.7+ | Cost-free unit testing |
+| Provider functions | 1.8+ | Provider-specific data transformation |
+| Cross-variable validation | 1.9+ | Validate relationships between variables |
+| Write-only arguments | 1.11+ | Secrets never stored in state |
+
+### Quick Examples
+
+```hcl
+# 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](references/code-patterns.md#modern-terraform-features-10)
+
+## 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](references/quick-reference.md#terraform-vs-opentofu-comparison).
+
+## Detailed Guides
+
+This skill uses **progressive disclosure** - essential information is in this main file, detailed guides are available when needed:
+
+📚 **Reference Files:**
+- **[Testing Frameworks](references/testing-frameworks.md)** - In-depth guide to static analysis, native tests, and Terratest
+- **[Module Patterns](references/module-patterns.md)** - Module structure, variable/output best practices, ✅ DO vs ❌ DON'T patterns
+- **[CI/CD Workflows](references/ci-cd-workflows.md)** - GitHub Actions, GitLab CI templates, cost optimization, automated cleanup
+- **[Security & Compliance](references/security-compliance.md)** - Trivy/Checkov integration, secrets management, compliance testing
+- **[Quick Reference](references/quick-reference.md)** - 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.
+
+## License
+
+This skill is licensed under the **Apache License 2.0**. See the LICENSE file for full terms.
+
+**Copyright © 2026 Anton Babenko**