Format Variable and Output Blocks

Formatting Variables and Outputs

Variable and output blocks are the interface of a Terraform module. Clean formatting makes the module's API immediately understandable to consumers.

Variable Block Examples

variable "environment" {
  description = "Deployment environment name"
  type        = string
  default     = "development"

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

variable "vpc_config" {
  description = "VPC configuration settings"
  type = object({
    cidr_block         = string
    enable_nat_gateway = bool
    single_nat_gateway = bool
    azs                = list(string)
  })
  default = {
    cidr_block         = "10.0.0.0/16"
    enable_nat_gateway = true
    single_nat_gateway = false
    azs                = ["us-east-1a", "us-east-1b", "us-east-1c"]
  }
}

variable "tags" {
  description = "Common tags applied to all resources"
  type        = map(string)
  default     = {}
}

Output Block Examples

output "vpc_id" {
  description = "The ID of the VPC"
  value       = aws_vpc.main.id
}

output "private_subnet_ids" {
  description = "List of private subnet IDs"
  value       = aws_subnet.private[*].id
}

output "database_endpoint" {
  description = "RDS instance endpoint"
  value       = aws_db_instance.main.endpoint
  sensitive   = true
}

Formatting Conventions

• Attribute order: description first, then type, then default, then validation
• Aligned equals: All top-level attributes within a variable or output block are aligned
• Complex types: object({}) and list() type definitions have their fields indented and aligned
• Default values: Complex defaults mirror the type structure with consistent indentation
• Sensitive outputs: The sensitive = true flag is aligned with other attributes