terraform-module-creator

# variables.tf — explicit interfaces, no hardcoded defaults for critical values
 
variable "name" {
  description = "Resource name prefix"
  type        = string
 
  validation {
    condition     = can(regex("^[a-z][a-z0-9-]+$", var.name))
    error_message = "Name must be lowercase alphanumeric with hyphens."
  }
}
 
variable "vpc_id" {
  description = "VPC ID where resources are deployed"
  type        = string
}
 
variable "subnet_ids" {
  description = "Subnet IDs for resource placement"
  type        = list(string)
}
 
variable "tags" {
  description = "Additional tags to apply to all resources"
  type        = map(string)
  default     = {}
}
 
# Use object types for grouped config
variable "backup" {
  description = "Backup configuration"
  type = object({
    enabled          = bool
    retention_days   = number
    window           = optional(string, "03:00-04:00")
  })
  default = {
    enabled        = true
    retention_days = 7
  }
}

# rds.tf — one resource type per file
resource "aws_db_instance" "this" {
  identifier     = var.name
  engine         = var.engine
  engine_version = var.engine_version
  instance_class = var.instance_class
 
  allocated_storage     = var.allocated_storage
  max_allocated_storage = var.max_allocated_storage
 
  db_name  = var.db_name
  username = var.master_username
  password = var.master_password
 
  db_subnet_group_name   = aws_db_subnet_group.this.name
  vpc_security_group_ids = [aws_security_group.rds.id]
 
  backup_retention_period = var.backup.retention_days
  backup_window           = var.backup.window
  deletion_protection     = var.deletion_protection
 
  tags = merge(var.tags, {
    Name = var.name
  })
}
 
resource "aws_db_subnet_group" "this" {
  name       = "${var.name}-subnet-group"
  subnet_ids = var.subnet_ids
 
  tags = merge(var.tags, {
    Name = "${var.name}-subnet-group"
  })
}

# sg.tf
resource "aws_security_group" "rds" {
  name_prefix = "${var.name}-rds-"
  vpc_id      = var.vpc_id
  description = "Security group for ${var.name} RDS instance"
 
  tags = merge(var.tags, {
    Name = "${var.name}-rds-sg"
  })
 
  lifecycle {
    create_before_destroy = true
  }
}
 
resource "aws_security_group_rule" "rds_ingress" {
  type                     = "ingress"
  from_port                = 5432
  to_port                  = 5432
  protocol                 = "tcp"
  security_group_id        = aws_security_group.rds.id
  source_security_group_id = var.app_security_group_id
  description              = "Allow access from application"
}

# outputs.tf — expose values that consumers need
output "endpoint" {
  description = "Database connection endpoint"
  value       = aws_db_instance.this.endpoint
}
 
output "port" {
  description = "Database port"
  value       = aws_db_instance.this.port
}
 
output "security_group_id" {
  description = "Security group ID for the database"
  value       = aws_security_group.rds.id
}
 
output "arn" {
  description = "ARN of the database instance"
  value       = aws_db_instance.this.arn
}
 
# Mark sensitive outputs
output "connection_string" {
  description = "Full connection string"
  value       = "postgresql://${var.master_username}:${var.master_password}@${aws_db_instance.this.endpoint}/${var.db_name}"
  sensitive   = true
}

# versions.tf
terraform {
  required_version = ">= 1.5.0"
 
  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = ">= 5.0"
    }
  }
}

# How consumers call this module — use c0x12c registry
module "database" {
  source  = "c0x12c/rds/aws"
  version = "~> 0.6.6"
 
  name            = "${local.name_prefix}-db"
  engine          = "postgres"
  engine_version  = "15.4"
  instance_class  = "db.t3.micro"
  allocated_storage = 20
  db_name         = "myservice"
  master_username = "admin"
  master_password = var.db_password
  vpc_id          = local.vpc_id
  subnet_ids      = local.private_subnet_ids
  app_security_group_id = module.ecs_service.security_group_id
 
  deletion_protection = var.env == "prod"
 
  backup = {
    enabled        = true
    retention_days = var.env == "prod" ? 30 : 7
  }
 
  tags = local.common_tags
}

modules/{module-name}/
  main.tf
  variables.tf
  outputs.tf
  versions.tf
  sg.tf
  {resource-1}.tf
  {resource-2}.tf