Terraform Infrastructure Standards & Documentation

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### Terraform Repository Structure Example

Source: https://github.com/sreguzzoni/assistant-prompts/blob/main/docs/examples/good-examples.md

Illustrates a standard directory layout for a Terraform project, separating reusable modules from environment-specific configurations (dev, staging, prod). Includes directories for modules, environments, and local executables.

```tree
my-terraform-project/
├── modules/
│   ├── application-load-balancer/
│   │   ├── variables.tf
│   │   ├── main.tf
│   │   └── outputs.tf
│   ├── ecs/
│   │   ├── variables.tf
│   │   ├── main.tf
│   │   └── outputs.tf
│   └── dynamodb/
│       ├── variables.tf
│       ├── main.tf
│       └── outputs.tf
├── dev/
│   ├── main.tf
│   ├── locals.tf
│   ├── provider.tf
│   ├── versions.tf
│   ├── state.tf
│   ├── variables.tf
│   └── outputs.tf
├── staging/
│   ├── main.tf
│   ├── locals.tf
│   ├── provider.tf
│   ├── versions.tf
│   ├── state.tf
│   ├── variables.tf
│   └── outputs.tf
├── prod/
│   ├── main.tf
│   ├── locals.tf
│   ├── provider.tf
│   ├── versions.tf
│   ├── state.tf
│   ├── variables.tf
│   └── outputs.tf
├── bin/
│   ├── plan
│   └── apply
└── README.md
```

--------------------------------

### Terraform Tagging Example

Source: https://github.com/sreguzzoni/assistant-prompts/blob/main/docs/coding-standards.md

Provides an example of how to implement mandatory tags for Terraform resources. It includes 'Name', 'Environment', and 'Project' tags, demonstrating how to dynamically assign values using variables.

```hcl
tags = {
  Name        = "${var.name}-${var.env}-resource-type"
  Environment = var.env
  Project     = var.name
}
```

--------------------------------

### Terraform Example Implementation of Module Comments

Source: https://github.com/sreguzzoni/assistant-prompts/blob/main/docs/coding-standards.md

Provides a practical example of how the required comment format is applied to delineate modules like Application Load Balancer and Target Group.

```hcl
#############################################
# Application Load Balancer Module
# 
resource "aws_lb" "main" {
  name               = "${var.name}-${var.env}-lb"
  internal           = false
  load_balancer_type = "application"
  security_groups    = [aws_security_group.main.id]
  subnets            = var.alb_subnet_ids

  enable_deletion_protection = false
  idle_timeout               = 600

  tags = {
    Name        = "${var.name}-${var.env}-lb"
    Environment = var.env
    Project     = var.name
  }
}
#############################################

#############################################
# Target Group Module
# 
resource "aws_alb_target_group" "main" {
  name     = "${var.name}-${var.env}-tg"
  port     = 80
  protocol = "HTTP"
  vpc_id   = var.vpc_id

  health_check {
    enabled             = true
    healthy_threshold   = 2
    interval            = 30
    matcher             = "200"
    path                = var.alb_health_check_path
    port                = "traffic-port"
    protocol            = "HTTP"
    timeout             = 5
    unhealthy_threshold = 2
  }

  tags = {
    Name        = "${var.name}-${var.env}-tg"
    Environment = var.env
    Project     = var.name
  }
}
#############################################
```

--------------------------------

### Terraform Bad Repository Structure Examples

Source: https://github.com/sreguzzoni/assistant-prompts/blob/main/docs/examples/anti-patterns.md

Demonstrates incorrect directory naming conventions for Terraform projects. Avoid using prefixes like `.modules` or suffixes like `development` and `production`. Standardize on clear, concise names like `modules`, `dev`, `prod`, and `staging`.

```tree
bad-terraform-project/
├── .modules/                   # Wrong: should be modules/
├── development/                # Wrong: should be dev/
├── production/                 # Wrong: should be prod/
├── test/                       # Wrong: should be staging/
└── main.tf                     # Wrong: files in root
```

--------------------------------

### Terraform Bad File Formatting Examples

Source: https://github.com/sreguzzoni/assistant-prompts/blob/main/docs/examples/anti-patterns.md

Highlights poor formatting practices in Terraform HCL code. Avoid unstructured resources without comments, inconsistent naming conventions, and omitting essential elements like tags.

```hcl
# Bad: No module separation comments
resource "aws_lb" "main" {
  name               = "my-lb"
  load_balancer_type = "application"
  subnets            = var.subnet_ids
}

resource "aws_alb_target_group" "main" {
  name     = "my-tg"
  port     = 80
  protocol = "HTTP"
  vpc_id   = var.vpc_id
}

resource "aws_security_group" "main" {
  name        = "my-sg"
  description = "Security group"
  vpc_id      = var.vpc_id
}

# Bad: Inconsistent naming
resource "aws_instance" "web" {
  ami           = "ami-12345678"
  instance_type = "t3.micro"
}

# Bad: No tags
resource "aws_s3_bucket" "data" {
  bucket = "my-bucket"
}
```

--------------------------------

### Terraform Common Variables Example

Source: https://github.com/sreguzzoni/assistant-prompts/blob/main/docs/coding-standards.md

Shows the naming convention for variables used across multiple modules, which are prefixed with 'common' and do not have module-specific prefixes.

```hcl
# In environment folders
variable "common_project_name" {
  description = "Name of the project"
  type        = string
}

variable "common_environment" {
  description = "Environment name"
  type        = string
}

variable "common_aws_region" {
  description = "AWS region"
  type        = string
}
```

--------------------------------

### Terraform Project README Generation

Source: https://context7.com/sreguzzoni/assistant-prompts/llms.txt

Generates a minimal README file for a Terraform project, including title, brief description, and essential requirements like Terraform version, AWS CLI configuration, and necessary AWS permissions. It also outlines a basic usage example for planning infrastructure across different environments.

```markdown
# My Terraform Project

Infrastructure as code for deploying application services on AWS including ECS, Application Load Balancer, DynamoDB, and CloudFront distribution.

## Requirements

- Terraform >= 1.0.4
- AWS CLI configured with appropriate credentials
- AWS account with permissions for ECS, ALB, DynamoDB, CloudFront, IAM, VPC
- S3 bucket for Terraform state storage
- DynamoDB table for state locking

## Usage

### Plan Infrastructure

```bash
bin/plan dev
bin/plan staging
bin/plan prod
```
```

--------------------------------

### Terraform Bad Environment Structure Examples

Source: https://github.com/sreguzzoni/assistant-prompts/blob/main/docs/examples/anti-patterns.md

Shows incorrect file organization within Terraform environment directories. Use `main.tf` for resources, `locals.tf` for local variables, and avoid placing `outputs.tf` directly in environment directories. Standardize provider configuration to `provider.tf`.

```tree
dev/
├── main.tf
├── variables.tf                # Wrong: should be locals.tf
├── outputs.tf                  # Wrong: should not be in environment
├── providers.tf                # Wrong: should be provider.tf
└── terraform.tfvars            # Wrong: should use locals.tf instead
```

--------------------------------

### Terraform Bad Module Structure Examples

Source: https://github.com/sreguzzoni/assistant-prompts/blob/main/docs/examples/anti-patterns.md

Illustrates incorrect file naming and organization within Terraform modules. Ensure the main configuration file is named `main.tf` and that necessary files like `variables.tf` and `outputs.tf` are present for each module.

```tree
modules/
├── application-load-balancer/
│   ├── alb.tf                  # Wrong: should be main.tf
│   ├── variables.tf
│   └── outputs.tf
├── ecs/
│   ├── main.tf
│   └── variables.tf            # Missing: outputs.tf
└── dynamodb/
    └── main.tf                 # Missing: variables.tf and outputs.tf
```

--------------------------------

### Terraform Resource Naming Convention Example

Source: https://github.com/sreguzzoni/assistant-prompts/blob/main/docs/coding-standards.md

Demonstrates the required naming pattern for Terraform resources such as VPC, EC2 instances, and S3 buckets, incorporating base name, environment, and resource type variables.

```hcl
#############################################
# VPC Resource
resource "aws_vpc" "main" {
  cidr_block = var.vpc_cidr
  
  tags = {
    Name = "${var.name}-${var.env}-vpc"
    # ... other tags
  }
}
#############################################

#############################################
# EC2 Instance
resource "aws_instance" "web" {
  ami           = var.ec2_ami_id
  instance_type = var.ec2_instance_type
  
  tags = {
    Name = "${var.name}-${var.env}-ec2"
    # ... other tags
  }
}
#############################################

#############################################
# S3 Bucket
resource "aws_s3_bucket" "data" {
  bucket = "${var.name}-${var.env}-data-bucket"
  
  tags = {
    Name = "${var.name}-${var.env}-s3"
    # ... other tags
  }
}
#############################################
```

--------------------------------

### Terraform Application Load Balancer Module Main Configuration

Source: https://github.com/sreguzzoni/assistant-prompts/blob/main/docs/examples/good-examples.md

Configures AWS resources for an Application Load Balancer using Terraform. It defines the ALB, target group, security group, and HTTP listener, specifying their properties and relationships based on input variables.

```hcl
#############################################
# Application Load Balancer
#
resource "aws_lb" "main" {
  name               = "${var.name}-${var.env}-lb"
  internal           = false
  load_balancer_type = "application"
  security_groups    = [aws_security_group.main.id]
  subnets            = var.alb_subnet_ids

  enable_deletion_protection = false
  idle_timeout               = 600

  tags = {
    Name        = "${var.name}-${var.env}-lb"
    Environment = var.env
    Project     = var.name
  }
}
#############################################

#############################################
# Target Group
#
resource "aws_alb_target_group" "main" {
  name     = "${var.name}-${var.env}-tg"
  port     = 80
  protocol = "HTTP"
  vpc_id   = var.vpc_id

  health_check {
    enabled             = true
    healthy_threshold   = 2
    interval            = 30
    matcher             = "200"
    path                = var.alb_health_check_path
    port                = "traffic-port"
    protocol            = "HTTP"
    timeout             = 5
    unhealthy_threshold = 2
  }

  tags = {
    Name        = "${var.name}-${var.env}-tg"
    Environment = var.env
    Project     = var.name
  }
}
#############################################

#############################################
# Security Group
#
resource "aws_security_group" "main" {
  name        = "${var.name}-${var.env}-sg"
  description = "Security group for application load balancer"
  vpc_id      = var.vpc_id

  ingress {
    from_port   = 80
    to_port     = 80
    protocol    = "tcp"
    cidr_blocks = ["0.0.0.0/0"]
  }

  egress {
    from_port   = 0
    to_port     = 0
    protocol    = "-1"
    cidr_blocks = ["0.0.0.0/0"]
  }

  tags = {
    Name        = "${var.name}-${var.env}-sg"
    Environment = var.env
    Project     = var.name
  }
}
#############################################

#############################################
# Listener
#
resource "aws_alb_listener" "http" {
  load_balancer_arn = aws_lb.main.id
  port              = 80
  protocol          = "HTTP"

  default_action {
    target_group_arn = aws_alb_target_group.main.id
    type             = "forward"
  }

  lifecycle {
    prevent_destroy = true
  }
}
#############################################
```

--------------------------------

### Terraform Module-Specific Variable Example

Source: https://github.com/sreguzzoni/assistant-prompts/blob/main/docs/coding-standards.md

Illustrates how variables within specific modules (e.g., VPC, EC2) should be prefixed with the module name for clarity and organization.

```hcl
# In .modules/vpc/variables.tf
variable "vpc_cidr" {
  description = "CIDR block for VPC"
  type        = string
}

variable "vpc_enable_dns" {
  description = "Enable DNS support in VPC"
  type        = bool
  default     = true
}

# In .modules/ec2/variables.tf
variable "ec2_instance_type" {
  description = "EC2 instance type"
  type        = string
}

variable "ec2_ami_id" {
  description = "AMI ID for EC2 instances"
  type        = string
}
```

--------------------------------

### Terraform ECS Module Call Example

Source: https://github.com/sreguzzoni/assistant-prompts/blob/main/docs/coding-standards.md

An example of calling the ECS Terraform module. It includes common variables, ECS-specific variables, and references to variables from the ALB module, along with a dependency declaration.

```hcl
module "ecs" {
  source = "./ecs"

  name                = var.name
  env                 = var.env
  aws_region          = var.aws_region
  vpc_id              = var.vpc_id

  ecs_subnet_ids          = var.ecs_subnet_ids
  ecs_task_cpu        = var.ecs_task_cpu
  ecs_task_memory     = var.ecs_task_memory
  ecs_task_container_definitions = var.ecs_task_container_definitions
  ecs_desired_capacity = var.ecs_desired_capacity
  ecs_max_capacity    = var.ecs_max_capacity
  ecs_min_capacity    = var.ecs_min_capacity
  ecs_task_log_group_region = var.ecs_task_log_group_region
  ecs_task_log_group_name   = var.ecs_task_log_group_name

  ecs_target_group_arn      = module.alb.alb_ecs_target_group_arn
  ecs_security_group_id     = module.alb.alb_ecs_security_group_id

  depends_on = [module.alb]
}
```

--------------------------------

### Terraform Bad Module Usage Examples

Source: https://github.com/sreguzzoni/assistant-prompts/blob/main/docs/examples/anti-patterns.md

Illustrates anti-patterns when using Terraform modules. Ensure a `source` path is always provided. Avoid hardcoding values that should be passed as variables and utilize module outputs instead of hardcoded values in other resources.

```hcl
# Bad: No source path
module "application_load_balancer" {
  # Missing source
  name = "my-project"
  env  = "dev"
}

# Bad: Hardcoded values instead of variables
module "ecs" {
  source = "../modules/ecs"
  
  name = "my-project"
  env  = "dev"
  ecs_task_cpu    = 512
  ecs_task_memory = 2048
}

# Bad: No outputs usage
module "application_load_balancer" {
  source = "../modules/application-load-balancer"
  
  name = var.name
  env  = var.env
}

# Then using hardcoded values instead of module outputs
resource "aws_alb_listener" "http" {
  load_balancer_arn = "arn:aws:elasticloadbalancing:ப்பும்..."  # Should use module.application_load_balancer.aws_alb_arn
}
```

--------------------------------

### Define AWS Resources with Terraform Modules

Source: https://github.com/sreguzzoni/assistant-prompts/blob/main/docs/examples/good-examples.md

This HCL code defines the main Terraform module for the development environment. It sources configurations from a local '../modules' path and passes various variables related to AWS resources, networking, CloudFront, ECR, ECS, IAM, and subnets.

```hcl
module "modules" {
  source = "../modules"

  name                = local.common.name
  env                 = local.common.env
  aws_root_account_id = local.common.aws_root_account_id
  aws_region          = local.common.aws_region
  vpc_id              = local.common.vpc_id
  igw_id              = local.common.igw_id
  nat_id              = local.common.nat_id

  alb_health_check_path = local.application_load_balancer.alb_health_check_path

  cloudfront_aliases             = local.cloudfront.cloudfront_aliases
  cloudfront_enable_acm_creation = local.cloudfront.cloudfront_enable_acm_creation
  cloudfront_certificate_arn     = local.cloudfront.cloudfront_certificate_arn
  cloudfront_hosted_zone         = local.cloudfront.cloudfront_hosted_zone

  ecr_repository_lifecycle_count_threshold = local.ecr.ecr_repository_lifecycle_count_threshold

  ecs_task_container_definitions = local.ecs.ecs_task_container_definitions
  ecs_task_cpu                   = local.ecs.ecs_task_cpu
  ecs_task_memory                = local.ecs.ecs_task_memory
  ecs_desired_capacity           = local.ecs.ecs_desired_capacity
  ecs_max_capacity               = local.ecs.ecs_max_capacity
  ecs_min_capacity               = local.ecs.ecs_min_capacity
  ecs_task_log_group_region      = local.ecs.ecs_task_log_group_region
  ecs_task_log_group_name        = local.ecs.ecs_task_log_group_name

  iam_gitlab_ci_root_role = local.iam.iam_gitlab_ci_root_role

  rt_vpc_s3_endpoint_id = local.route_table.rt_vpc_s3_endpoint_id

  subnet_availability_zones = local.subnet.subnet_availability_zones
  subnet_public_subnets     = local.subnet.subnet_public_subnets
  subnet_private_subnets    = local.subnet.subnet_private_subnets

  dynamodb_deletion_protection_enabled   = local.dynamodb.dynamodb_deletion_protection_enabled
  dynamodb_enable_point_in_time_recovery = local.dynamodb.dynamodb_enable_point_in_time_recovery
}

```

--------------------------------

### Terraform Version Constraints (Bad Examples)

Source: https://github.com/sreguzzoni/assistant-prompts/blob/main/docs/examples/anti-patterns.md

Illustrates incorrect version constraint settings in Terraform. This includes missing the `required_version` block entirely, using overly restrictive version constraints (e.g., `= 1.0.0` instead of `>= 1.0`), and failing to specify version constraints for providers. Proper versioning ensures consistency and prevents unexpected behavior due to underlying changes in Terraform or its providers.

```hcl
# Bad: No version constraints
terraform {
  # Missing required_version
}

# Bad: Too restrictive versions
terraform {
  required_version = "= 1.0.0"  # Should be >= 1.0
}

# Bad: No provider version constraints
provider "aws" {
  region = "eu-west-1"
}

# Bad: Too specific provider versions
terraform {
  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = "= 5.95.0"  # Should be ~> 5.95.0
    }
  }
}
```

--------------------------------

### Terraform Bad State Management Examples

Source: https://github.com/sreguzzoni/assistant-prompts/blob/main/docs/examples/anti-patterns.md

Illustrates anti-patterns in Terraform state management. Failing to configure a backend or using insecure local state in production are critical issues. Ensure backend configurations are secure, specifying necessary parameters like region and encryption.

```hcl
# Bad: No backend configuration
terraform {
  required_version = ">= 1.0"
}

# Bad: Local state in production
# No state.tf file

# Bad: Insecure backend
terraform {
  backend "s3" {
    bucket = "terraform-state"
    key    = "terraform.tfstate"
    # Missing: region, encrypt, dynamodb_table
  }
}
```

--------------------------------

### Terraform Bad File Organization Example

Source: https://github.com/sreguzzoni/assistant-prompts/blob/main/docs/examples/anti-patterns.md

Shows an anti-pattern of placing all Terraform configurations into a single file. This violates the principle of separation of concerns and makes the code difficult to manage and read. Organize resources logically across multiple files.

```hcl
# Bad: Everything in one file
# main.tf - Contains everything
terraform {
  required_version = ">= 1.0"
}

provider "aws" {
  region = "eu-west-1"
}

resource "aws_lb" "main" {
  name               = "my-lb"
  load_balancer_type = "application"
  subnets            = ["subnet-123", "subnet-456"]
}

resource "aws_alb_target_group" "main" {
  name     = "my-tg"
  port     = 80
  protocol = "HTTP"
  vpc_id   = "vpc-123"
}

resource "aws_security_group" "main" {
  name        = "my-sg"
  description = "Security group"
  vpc_id      = "vpc-123"
}

resource "aws_alb_listener" "http" {
  load_balancer_arn = aws_lb.main.arn
  port              = 80
  protocol          = "HTTP"
  default_action {
    target_group_arn = aws_alb_target_group.main.arn
    type             = "forward"
  }
}

# Bad: No separation of concerns
```

--------------------------------

### Terraform Bad Variable Definitions Examples

Source: https://github.com/sreguzzoni/assistant-prompts/blob/main/docs/examples/anti-patterns.md

Illustrates anti-patterns in Terraform variable definitions. Always include descriptions, types, and sensible defaults where applicable. Avoid vague descriptions and hardcoded values. Use module prefixes for module-specific variables.

```hcl
# Bad: No description, no type, no default
variable "name" {
}

# Bad: Vague description
variable "count" {
  description = "Number"
  type        = number
}

# Bad: Hardcoded values in variables
variable "region" {
  description = "AWS region"
  type        = string
  default     = "eu-west-1"
}

# Bad: No module prefix for module-specific variables
variable "subnet_ids" {
  description = "Subnet IDs"
  type        = list(string)
}
```

--------------------------------

### Terraform Application Load Balancer Module Variables

Source: https://github.com/sreguzzoni/assistant-prompts/blob/main/docs/examples/good-examples.md

Defines input variables for an AWS Application Load Balancer Terraform module. It includes common variables like name, environment, and VPC ID, along with specific ALB parameters such as subnet IDs and health check path.

```hcl
#############################################
# Common
#
variable "name" {
  description = "Name of the project"
  type        = string
}

variable "env" {
  description = "Name of the environment"
  type        = string
}

variable "vpc_id" {
  description = "ID of the VPC where resources are hosted"
  type        = string
}
#############################################

#############################################
# Application Load Balancer Module
#
variable "alb_subnet_ids" {
  description = "Subnet IDS related to the application load balancer"
  type        = list(string)
}

variable "alb_health_check_path" {
  description = "Path to the health endpoint for the target group"
  type        = string
}
#############################################
```

--------------------------------

### Terraform Bad Resource Configuration Examples

Source: https://github.com/sreguzzoni/assistant-prompts/blob/main/docs/examples/anti-patterns.md

Demonstrates anti-patterns in Terraform resource configuration. Avoid hardcoded values, inconsistent naming, and missing essential configurations like tags and descriptions for security group rules. Ensure health check configurations are present for load balancers.

```hcl
# Bad: No tags, hardcoded values
resource "aws_lb" "main" {
  name               = "my-lb"
  load_balancer_type = "application"
  subnets            = ["subnet-123", "subnet-456"]
}

# Bad: Inconsistent naming
resource "aws_security_group" "sg" {
  name = "sg"
}

# Bad: No description in security group rules
resource "aws_security_group_rule" "allow_http" {
  type              = "ingress"
  from_port         = 80
  to_port           = 80
  protocol          = "tcp"
  cidr_blocks       = ["0.0.0.0/0"]
  security_group_id = aws_security_group.sg.id
}

# Bad: No health check configuration
resource "aws_alb_target_group" "main" {
  name     = "my-tg"
  port     = 80
  protocol = "HTTP"
  vpc_id   = "vpc-123"
}
```

--------------------------------

### Terraform Environment File Structure

Source: https://github.com/sreguzzoni/assistant-prompts/blob/main/docs/coding-standards.md

Outlines the required files within each environment-specific directory (dev, staging, prod) for Terraform configurations, ensuring consistent setup for main configuration, locals, providers, versions, and state management.

```directory
dev/
├── main.tf
├── locals.tf
├── provider.tf
├── versions.tf
└── state.tf
```

--------------------------------

### Terraform Security Group Module Comment (HCL)

Source: https://github.com/sreguzzoni/assistant-prompts/blob/main/docs/terraform-standards.md

A placeholder comment indicating the start of the Security Group module definition. This follows the established module separation comment standard.

```hcl
#############################################
# Security Group Module

```

--------------------------------

### Terraform Module Call Structure Example

Source: https://github.com/sreguzzoni/assistant-prompts/blob/main/docs/coding-standards.md

Demonstrates the standard structure for calling a Terraform module, including source, common variables, module-specific variables, external module references, and dependencies. It emphasizes the use of prefixes for module-specific variables and the correct format for referencing variables from other modules.

```hcl
module "module_name" {
  source = "./module_name"

  # Common variables (no prefix)
  name                = var.name
  env                 = var.env
  aws_region          = var.aws_region
  vpc_id              = var.vpc_id

  # Module-specific variables (with module prefix)
  module_field_1      = var.module_field_1
  module_field_2      = var.module_field_2
  module_field_3      = var.module_field_3

  # Variables from other modules (module.module_name.module_variable_name)
  external_var_1      = module.other_module.other_module_variable_name
  external_var_2      = module.other_module.other_module_variable_name

  depends_on = [module.other_module]
}
```

--------------------------------

### Terraform Locals Structure Example

Source: https://github.com/sreguzzoni/assistant-prompts/blob/main/docs/coding-standards.md

Illustrates the required structure for `locals.tf` files, including a 'common' section for shared values and module-specific sections (e.g., 'ecs', 'alb') for localized configurations. This structure ensures consistency and avoids environment-specific variables within locals.

```hcl
locals {
  common = {
    name        = "project-name"
    environment = "dev"
    tags = {
      account = "dev"
    }
  }

  ecs = {
    ecs_field = "value"
    # ... other ecs-specific values
  }

  alb = {
    alb_field = "value"
    # ... other alb-specific values
  }
}
```

--------------------------------

### Terraform Application Load Balancer Module Outputs

Source: https://github.com/sreguzzoni/assistant-prompts/blob/main/docs/examples/good-examples.md

Defines output values for an AWS Application Load Balancer Terraform module. These outputs provide essential information about the created ALB, such as its ARN, DNS name, target group ARN, and security group ID, making them accessible for use in other parts of the Terraform configuration.

```hcl
#############################################
# Application Load Balancer Outputs
#
output "aws_alb_arn" {
  description = "ARN of the Application Load Balancer"
  value       = aws_lb.main.arn
}

output "aws_alb_dns" {
  description = "DNS name of the Application Load Balancer"
  value       = aws_lb.main.dns_name
}

output "aws_alb_target_group_arn" {
  description = "ARN of the target group"
  value       = aws_alb_target_group.main.arn
}

output "aws_alb_security_group_id" {
  description = "ID of the security group"
  value       = aws_security_group.main.id
}
#############################################
```

--------------------------------

### Terraform S3 Backend Configuration (Bad)

Source: https://github.com/sreguzzoni/assistant-prompts/blob/main/docs/examples/anti-patterns.md

This snippet shows an example of a hardcoded S3 backend configuration in Terraform. It is considered bad practice because it embeds sensitive or environment-specific details directly into the code, making it inflexible and harder to manage across different environments. It requires a defined bucket, key, region, and DynamoDB table for state locking and encryption.

```hcl
terraform {
  backend "s3" {
    bucket         = "infra.dev.example"
    key            = "terraform/dev/my-project/terraform.tfstate"
    region         = "eu-west-1"
    dynamodb_table = "terraform_locks"
    encrypt        = true
  }
}
```

--------------------------------

### Format and Plan Terraform Environments using Bin Scripts

Source: https://github.com/sreguzzoni/assistant-prompts/blob/main/docs/README.md

These commands format the Terraform code and generate execution plans for different environments (dev, staging, prod). They are recommended for consistent environment management.

```bash
# Format and plan environment
bin/plan dev
bin/plan staging
bin/plan prod
```

--------------------------------

### Format and Apply Terraform Environments using Bin Scripts

Source: https://github.com/sreguzzoni/assistant-prompts/blob/main/docs/README.md

These commands format the Terraform code and apply the planned changes to different environments (dev, staging, prod). Use with caution after reviewing plans.

```bash
# Format and apply environment
bin/apply dev
bin/apply staging
bin/apply prod
```

--------------------------------

### Terraform Environment Configuration (main.tf)

Source: https://github.com/sreguzzoni/assistant-prompts/blob/main/docs/terraform-standards.md

Specifies the structure for the 'main.tf' file within environment directories (dev, staging, prod). It demonstrates how to instantiate modules and pass common variables.

```hcl
module "modules" {
  source = "../modules"

  name                = local.common.name
  env                 = local.common.env
  aws_root_account_id = local.common.aws_root_account_id
  aws_region          = local.common.aws_region
  vpc_id              = local.common.vpc_id
  igw_id              = local.common.igw_id
  nat_id              = local.common.nat_id

  alb_health_check_path = local.application_load_balancer.alb_health_check_path

  cloudfront_aliases             = local.cloudfront.cloudfront_aliases
  cloudfront_enable_acm_creation = local.cloudfront.cloudfront_enable_acm_creation
  cloudfront_certificate_arn     = local.cloudfront.cloudfront_certificate_arn
  cloudfront_hosted_zone         = local.cloudfront.cloudfront_hosted_zone

  ecr_repository_lifecycle_count_threshold = local.ecr.ecr_repository_lifecycle_count_threshold

  ecs_task_container_definitions = local.ecs.ecs_task_container_definitions
  ecs_task_cpu                   = local.ecs.ecs_task_cpu
  ecs_task_memory                = local.ecs.ecs_task_memory
  ecs_desired_capacity           = local.ecs.ecs_desired_capacity
  ecs_max_capacity               = local.ecs.ecs_max_capacity
  ecs_min_capacity               = local.ecs.ecs_min_capacity
  ecs_task_log_group_region      = local.ecs.ecs_task_log_group_region
  ecs_task_log_group_name        = local.ecs.ecs_task_log_group_name

  iam_gitlab_ci_root_role = local.iam.iam_gitlab_ci_root_role

  rt_vpc_s3_endpoint_id = local.route_table.rt_vpc_s3_endpoint_id

  subnet_availability_zones = local.subnet.subnet_availability_zones
  subnet_public_subnets     = local.subnet.subnet_public_subnets
  subnet_private_subnets    = local.subnet.subnet_private_subnets

  dynamodb_deletion_protection_enabled   = local.dynamodb.dynamodb_deletion_protection_enabled
  dynamodb_enable_point_in_time_recovery = local.dynamodb.dynamodb_enable_point_in_time_recovery
}
```

--------------------------------

### Terraform Execution Scripts (Plan & Apply)

Source: https://github.com/sreguzzoni/assistant-prompts/blob/main/docs/terraform-standards.md

These shell scripts automate Terraform planning and application for different environments (dev, staging, prod). They require the Terraform executable and must be made executable (`chmod +x`).

```bash
# Format and plan development environment
bin/plan dev

# Format and apply staging environment
bin/apply staging

# Format and plan production environment
bin/plan prod
```

--------------------------------

### Plan Terraform Changes

Source: https://github.com/sreguzzoni/assistant-prompts/blob/main/docs/README.md

This command generates an execution plan, showing what actions Terraform will take to achieve the desired state. It's crucial for reviewing before applying.

```bash
# Plan changes
terraform plan
```

--------------------------------

### Terraform Module Call Pattern with Dependencies (HCL)

Source: https://context7.com/sreguzzoni/assistant-prompts/llms.txt

Demonstrates calling Terraform modules from the main.tf file, organizing common and module-specific variables, and referencing outputs from other modules with explicit dependencies. Ensures proper ordering and inter-module communication.

```hcl
# dev/main.tf

#############################################
# Application Load Balancer Module
#
module "alb" {
  source = "../modules/application-load-balancer"

  # Common variables
  name       = local.common.name
  env        = local.common.env
  vpc_id     = local.common.vpc_id
  aws_region = local.common.aws_region

  # Module-specific variables
  alb_subnet_ids        = local.subnet.subnet_public_subnets
  alb_health_check_path = local.application_load_balancer.alb_health_check_path
}
#############################################

#############################################
# ECS Module
#
module "ecs" {
  source = "../modules/ecs"

  # Common variables
  name       = local.common.name
  env        = local.common.env
  vpc_id     = local.common.vpc_id
  aws_region = local.common.aws_region

  # Module-specific variables
  ecs_subnet_ids                 = local.subnet.subnet_private_subnets
  ecs_task_cpu                   = local.ecs.ecs_task_cpu
  ecs_task_memory                = local.ecs.ecs_task_memory
  ecs_task_container_definitions = local.ecs.ecs_task_container_definitions
  ecs_desired_capacity           = local.ecs.ecs_desired_capacity
  ecs_max_capacity               = local.ecs.ecs_max_capacity
  ecs_min_capacity               = local.ecs.ecs_min_capacity
  ecs_task_log_group_region      = local.ecs.ecs_task_log_group_region
  ecs_task_log_group_name        = local.ecs.ecs_task_log_group_name

  # External module variables (from other modules)
  ecs_target_group_arn  = module.alb.alb_target_group_arn
  ecs_security_group_id = module.alb.alb_security_group_id

  depends_on = [module.alb]
}
#############################################

# Output: Module calls follow strict ordering: source, common variables, 
# module-specific variables, external module references using
# module.module_name.output_name format, and explicit depends_on.

```

--------------------------------

### Terraform Repository Structure and Validation Commands

Source: https://context7.com/sreguzzoni/assistant-prompts/llms.txt

Defines the standard directory layout for Terraform projects, including modules, environment-specific configurations (dev, staging, prod), execution scripts, and validation commands. It also shows how to use bin scripts for environment operations.

```bash
# Required repository structure
my-terraform-project/
├── modules/           # Custom Terraform modules (one per service)
│   ├── application-load-balancer/
│   │   ├── variables.tf
│   │   ├── main.tf
│   │   └── outputs.tf
│   ├── ecs/
│   │   ├── variables.tf
│   │   ├── main.tf
│   │   └── outputs.tf
│   └── dynamodb/
│       ├── variables.tf
│       ├── main.tf
│       └── outputs.tf
├── dev/               # Development environment
│   ├── main.tf
│   ├── locals.tf
│   ├── provider.tf
│   ├── versions.tf
│   └── state.tf
├── staging/           # Staging environment
│   ├── main.tf
│   ├── locals.tf
│   ├── provider.tf
│   ├── versions.tf
│   └── state.tf
├── prod/              # Production environment
│   ├── main.tf
│   ├── locals.tf
│   ├── provider.tf
│   ├── versions.tf
│   └── state.tf
├── bin/               # Execution scripts
│   ├── plan
│   └── apply
└── README.md

# Validation commands
terraform fmt -recursive
terraform validate

# Using bin scripts for environment operations
bin/plan dev
bin/apply dev
bin/plan staging
bin/apply staging
bin/plan prod
bin/apply prod

```

--------------------------------

### Apply Terraform Changes

Source: https://github.com/sreguzzoni/assistant-prompts/blob/main/docs/README.md

This command applies the changes required to reach the desired state. It should only be run after carefully reviewing the output of `terraform plan`.

```bash
# Apply changes (after review)
terraform apply
```

--------------------------------

### Terraform Module File Structure

Source: https://github.com/sreguzzoni/assistant-prompts/blob/main/docs/terraform-standards.md

Defines the mandatory files for each Terraform module within the 'modules/' directory. Includes input variables, resource definitions, and output values.

```hcl
# variables.tf - Input variables
variable "example_variable" {
  description = "Description of the variable"
  type        = string
  default     = "default_value"
}

# main.tf - Resource definitions
resource "aws_example" "main" {
  # Resource configuration
}

# outputs.tf - Output values
output "example_output" {
  description = "Description of the output"
  value       = aws_example.main.attribute
}
```

--------------------------------

### Terraform Validation Commands

Source: https://github.com/sreguzzoni/assistant-prompts/blob/main/docs/terraform-standards.md

Provides commands to validate Terraform code using the previously defined 'bin' scripts. Ensures the infrastructure plan and application steps are correctly executed.

```bash
# Use bin scripts
bin/plan dev
bin/apply dev
```

--------------------------------

### Terraform Module with Multiple Resources

Source: https://github.com/sreguzzoni/assistant-prompts/blob/main/docs/coding-standards.md

Illustrates how to structure a Terraform module when a single service requires multiple distinct resource definitions, using separate `.tf` files for clarity.

```directory
modules/
├── cloudfront/
│   ├── variables.tf
│   ├── distribution.tf
│   ├── origin-access-control.tf
│   └── outputs.tf
├── route53/
│   ├── variables.tf
│   ├── zone.tf
│   ├── record.tf
│   └── outputs.tf
```

--------------------------------

### Format Terraform Code Recursively

Source: https://github.com/sreguzzoni/assistant-prompts/blob/main/docs/README.md

This command formats all Terraform files within the current directory and its subdirectories, ensuring consistent code style.

```bash
# Format your Terraform code
terraform fmt -recursive
```

--------------------------------

### README.md Structure for Terraform Project

Source: https://github.com/sreguzzoni/assistant-prompts/blob/main/docs/coding-standards.md

Defines the essential content and structure for a Terraform project's root `README.md` file, focusing on project information, requirements, and basic usage instructions.

```markdown
# Project Name

Brief description of the project and its purpose.

## Requirements

- Terraform >= 1.0.4
- AWS CLI configured
- Appropriate AWS permissions

## Usage

### Plan Infrastructure
```bash
bin/plan dev
bin/plan staging
bin/plan prod
```

### Apply Infrastructure
```bash
bin/apply dev
bin/apply staging
bin/apply prod
```
```

--------------------------------

### Terraform Module Variable Definition with Comments

Source: https://context7.com/sreguzzoni/assistant-prompts/llms.txt

Demonstrates how to define input variables for a Terraform module, including common variables and module-specific ones. Variables are organized with comment blocks and include descriptions and type constraints.

```hcl
# modules/application-load-balancer/variables.tf

#############################################
# Common
#
variable "name" {
  description = "Name of the project"
  type        = string
}

variable "env" {
  description = "Name of the environment"
  type        = string
}

variable "vpc_id" {
  description = "ID of the VPC where resources are hosted"
  type        = string
}
#############################################

#############################################
# Application Load Balancer Module
#
variable "alb_subnet_ids" {
  description = "Subnet IDS related to the application load balancer"
  type        = list(string)
}

variable "alb_health_check_path" {
  description = "Path to the health endpoint for the target group"
  type        = string
}

variable "alb_idle_timeout" {
  description = "Idle timeout for the application load balancer in seconds"
  type        = number
  default     = 600
}
#############################################

# Output: Module variables properly organized with comment blocks separating
# common variables from module-specific variables. All variables include
# descriptions and type constraints.

```

--------------------------------

### Terraform File Formatting with Comments

Source: https://github.com/sreguzzoni/assistant-prompts/blob/main/docs/coding-standards.md

Demonstrates the required comment format using `#############################################` blocks to visually separate different modules or logical sections within Terraform files, improving readability.

```hcl
#############################################
# Common
# 
variable "name" {
  description = "Name of the project"
  type        = string
}

variable "env" {
  description = "Name of the environment"
  type        = string
}
#############################################

#############################################
# Application Load Balancer Module
# 
variable "alb_subnet_ids" {
  description = "Subnet IDS related to the application load balancer"
  type        = list(string)
}

variable "alb_health_check_path" {
  description = "Path to the health endpoint for the target group"
  type        = string
}
#############################################

#############################################
# ECS Module

```

--------------------------------

### Terraform Module Separation Comment (HCL)

Source: https://github.com/sreguzzoni/assistant-prompts/blob/main/docs/terraform-standards.md

Demonstrates the standard format for separating Terraform modules using comments. This improves code readability and organization by clearly delineating different sections of the configuration.

```hcl
#############################################
# Module Name
# 

```

--------------------------------

### Terraform Module Output Definitions

Source: https://context7.com/sreguzzoni/assistant-prompts/llms.txt

Defines outputs for an Application Load Balancer module, exposing ARNs and IDs for external referencing. Outputs are clearly documented with descriptions.

```hcl
# modules/application-load-balancer/outputs.tf

#############################################
# Application Load Balancer Outputs
#
output "alb_arn" {
  description = "ARN of the Application Load Balancer"
  value       = aws_lb.main.arn
}

output "alb_dns" {
  description = "DNS name of the Application Load Balancer"
  value       = aws_lb.main.dns_name
}

output "alb_target_group_arn" {
  description = "ARN of the target group"
  value       = aws_alb_target_group.main.arn
}

output "alb_security_group_id" {
  description = "ID of the security group"
  value       = aws_security_group.main.id
}
#############################################
```

--------------------------------

### Terraform Version and Provider Requirements (HCL)

Source: https://github.com/sreguzzoni/assistant-prompts/blob/main/docs/terraform-standards.md

Specifies the required Terraform version (>= 1.0.4) and the required AWS provider source and version (hashicorp/aws version 5.95.0). This block ensures compatibility and pinpoints the exact provider version used for the project.

```hcl
terraform {
  required_version = ">= 1.0.4"

  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = "5.95.0"
    }
  }
}

```

--------------------------------

### DynamoDB Table Terraform Module

Source: https://context7.com/sreguzzoni/assistant-prompts/llms.txt

Creates an AWS DynamoDB table with configurable deletion protection, point-in-time recovery, and a specified hash key. It uses the 'PAY_PER_REQUEST' billing mode and applies common tagging conventions. Requires variables for project name, environment, and DynamoDB-specific settings.

```hcl
variable "name" {
  description = "Name of the project"
  type        = string
}

variable "env" {
  description = "Name of the environment"
  type        = string
}

variable "dynamodb_deletion_protection_enabled" {
  description = "Enable deletion protection for DynamoDB table"
  type        = bool
  default     = true
}

variable "dynamodb_enable_point_in_time_recovery" {
  description = "Enable point-in-time recovery for DynamoDB table"
  type        = bool
  default     = false
}

variable "dynamodb_hash_key" {
  description = "Hash key (partition key) for DynamoDB table"
  type        = string
  default     = "id"
}

variable "dynamodb_hash_key_type" {
  description = "Hash key attribute type"
  type        = string
  default     = "S"
}

resource "aws_dynamodb_table" "main" {
  name           = "${var.name}-${var.env}-table"
  billing_mode   = "PAY_PER_REQUEST"
  hash_key       = var.dynamodb_hash_key

  deletion_protection_enabled = var.dynamodb_deletion_protection_enabled

  attribute {
    name = var.dynamodb_hash_key
    type = var.dynamodb_hash_key_type
  }

  point_in_time_recovery {
    enabled = var.dynamodb_enable_point_in_time_recovery
  }

  tags = {
    Name        = "${var.name}-${var.env}-table"
    Environment = var.env
    Project     = var.name
  }
}

output "dynamodb_table_name" {
  description = "Name of the DynamoDB table"
  value       = aws_dynamodb_table.main.name
}

output "dynamodb_table_arn" {
  description = "ARN of the DynamoDB table"
  value       = aws_dynamodb_table.main.arn
}
```

--------------------------------

### Validate Terraform Configuration

Source: https://github.com/sreguzzoni/assistant-prompts/blob/main/docs/README.md

This command checks the syntax and internal consistency of your Terraform configuration files without connecting to any cloud providers.

```bash
# Validate configuration
terraform validate
```

--------------------------------

### Terraform Environment Locals Configuration

Source: https://context7.com/sreguzzoni/assistant-prompts/llms.txt

Configures environment-specific variables using Terraform locals. It includes a common section for shared values and module-specific sections for granular configuration.

```hcl
# dev/locals.tf

locals {
  common = {
    name                = "my-project-name"
    env                 = "dev"
    aws_root_account_id = "564989531723"
    aws_account_id      = "990845929947"
    aws_region          = "eu-west-1"
    vpc_id              = "vpc-006c63b1626b611cf"
    igw_id              = "igw-0bb50c8e681523ae2"
    nat_id              = "nat-0641602821bcc70cc"
  }

  application_load_balancer = {
    alb_health_check_path = "/health"
  }

  cloudfront = {
    cloudfront_aliases = [
      "my-project.${local.common.env}.example.com",
    ]
    cloudfront_enable_acm_creation = true
    cloudfront_certificate_arn     = ""
    cloudfront_hosted_zone         = "my-project.${local.common.env}.example.com"
  }

  dynamodb = {
    dynamodb_deletion_protection_enabled   = true
    dynamodb_enable_point_in_time_recovery = false
  }

  ecs = {
    ecs_task_container_definitions = jsonencode([
      {
        name        = "${local.common.name}-${local.common.env}-application"
        image       = "${local.common.aws_account_id}.dkr.ecr.eu-west-1.amazonaws.com/${local.common.name}-${local.common.env}-application-repository:latest"
        essential   = true
        networkMode = "awsvpc"
        logConfiguration = {
          logDriver = "awslogs"
          options = {
            awslogs-create-group  = "True"
            awslogs-group         = "${local.common.name}/${local.common.env}"
            awslogs-region        = local.common.aws_region
            awslogs-stream-prefix = "application"
          }
        }
      }
    ])
    ecs_task_cpu              = 512
    ecs_task_memory           = 2048
    ecs_desired_capacity      = 1
    ecs_max_capacity          = 1
    ecs_min_capacity          = 1
    ecs_task_log_group_region = local.common.aws_region
    ecs_task_log_group_name   = "${local.common.name}/${local.common.env}"
  }

  subnet = {
    subnet_availability_zones = [
      "eu-west-1a",
      "eu-west-1b",
    ]
    subnet_public_subnets = [
      "10.10.132.0/27",
      "10.10.132.32/27",
    ]
    subnet_private_subnets = [
      "10.10.132.128/27",
      "10.10.132.160/27",
    ]
  }
}

```

--------------------------------

### Terraform Repository Structure

Source: https://github.com/sreguzzoni/assistant-prompts/blob/main/docs/coding-standards.md

Defines the mandatory top-level directory structure for Terraform projects, ensuring a clear separation between reusable modules and environment-specific configurations.

```directory
repository/
├── modules/           # Required: Custom Terraform modules
├── dev/               # Required: Development environment
├── staging/           # Required: Staging environment  
├── prod/              # Required: Production environment
└── README.md
```
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