terraform-style-guide

Files (2)

• SECURITY.md
• SKILL.md

SKILL.md (first lines)

# Terraform Style Guide

Generate and maintain Terraform code following HashiCorp's official style conventions and best practices.

**Reference:** [HashiCorp Terraform Style Guide](https://developer.hashicorp.com/terraform/language/style)

## Code Generation Strategy

When generating Terraform code:

1. Start with provider configuration and version constraints
2. Create data sources before dependent resources
3. Build resources in dependency order
4. Add outputs for key resource attributes
5. Use variables for all configurable values

## File Organization

| File | Purpose |
|------|---------|
| `terraform.tf` | Terraform and provider version requirements |
| `providers.tf` | Provider configurations |
| `main.tf` | Primary resources and data sources |
| `variables.tf` | Input variable declarations (alphabetical) |
| `outputs.tf` | Output value declarations (alphabetical) |
| `locals.tf` | Local value declarations |

### Example Structure

```hcl
# terraform.tf
terraform {
  required_version = ">= 1.14"

  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = "~> 6.0"
    }
  }
}

# variables.tf
variable "environment" {
  description = "Target deployment environment"
  type        = string

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

# locals.tf
locals {
  common_tags = {
    Environment = var.environment
    ManagedBy   = "Terraform"
  }
}

# main.tf
resource "aws_vpc" "main" {
  cidr_block           = var.vpc_cidr
  enable_dns_hostnames = true

  tags = merge(local.common_tags, {
    Name = "${var.project_name}-${var.environment}-vpc"
  })
}

# outputs.tf
output "vpc_id" {
  description = "ID of the created VPC"
  value       = aws_vpc.main.id
}
```

## Code Formatting

### Indentation and Alignment

- Use **two spaces** per nesting level (no tabs)
- Align equals signs for consecutive arguments

```hcl
resource "aws_instance" "web" {
  ami           = "ami-0c55b159cbfafe1f0"
  instance_type = "t2.micro"
  subnet_id     = "subnet-12345678"

  tags = {
    Name        = "web-server"
    Environment = "production"
  }
}
```

### Block Organization

Arguments precede blocks, with meta-arguments first:

```hcl
resource "aws_instance" "example" {
  # Meta-arguments
  count = 3

  # Arguments
  ami           = "ami-0c55b159cbfafe1f0"
  instance_type = "t2.micro"

  # Blocks
  root_block_device {
    volume_size = 20
  }

  # Lifecycle last
  lifecycle {
    create_before_destroy = true

From hashicorp/agent-skills, MPL-2.0.

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