Terraform Module Builder

Terraform Module Builder

Prerequisites & Dependencies

• Terraform CLI 1.5+ installed and configured
• Cloud provider credentials (AWS, GCP, Azure) via ~/.aws/credentials, gcloud, or az cli
• Text editor or IDE with HCL syntax highlighting
• Optional: tflint and terraform fmt for linting and formatting

Execution Steps

1. Define the module directory structure: variables.tf, inputs.tf, outputs.tf, main.tf, and an optional README.md
2. Write variables.tf with clear input variables: names, types, defaults, and validation rules (validation block)
3. Write main.tf with resource definitions that accept input variables and produce logical outputs
4. Write outputs.tf with descriptive output values that consumers can reference in other modules or scripts
5. Add a README.md explaining the module's purpose, inputs, outputs, usage examples, and versioning scheme
6. Test the module locally: terraform init, terraform plan, and terraform apply in a throwaway workspace
7. Version the module: create a vX.Y.Z git tag and push to a registry (Terraform Registry or private Git repo)

# variables.tf
variable "vpc_cidr" {
  description = "CIDR block for the VPC"
  type        = string
  default     = "10.0.0.0/16"
}

variable "instance_type" {
  description = "EC2 instance type"
  type        = string
  default     = "t3.micro"
}

# main.tf
resource "aws_vpc" "example" {
  cidr_block = var.vpc_cidr
}

resource "aws_instance" "example" {
  instance_type = var.instance_type
  ami           = data.aws_ami.default.id
  vpc_id        = aws_vpc.example.id
}

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

terraform init
terraform plan -var="vpc_cidr=10.1.0.0/16"
terraform apply -auto-approve