terraform-module-library

Terraform Module Library Production-ready Terraform module patterns for AWS, Azure, and GCP infrastructure. Do not use this skill when The task is unrelated to terraform module library You need a different domain or tool outside this scope Instructions Clarify goals, constraints, and required inputs. Apply relevant best practices and validate outcomes. Provide actionable steps and verification. If detailed examples are required, open resources/implementation-playbook.md . Purpose Create reusable, well-tested Terraform modules for common cloud infrastructure patterns across multiple cloud providers. Use this skill when Build reusable infrastructure components Standardize cloud resource provisioning Implement infrastructure as code best practices Create multi-cloud compatible modules Establish organizational Terraform standards Module Structure terraform-modules/ ├── aws/ │ ├── vpc/ │ ├── eks/ │ ├── rds/ │ └── s3/ ├── azure/ │ ├── vnet/ │ ├── aks/ │ └── storage/ └── gcp/ ├── vpc/ ├── gke/ └── cloud-sql/ Standard Module Pattern module-name/ ├── main.tf # Main resources ├── variables.tf # Input variables ├── outputs.tf # Output values ├── versions.tf # Provider versions ├── README.md # Documentation ├── examples/ # Usage examples │ └── complete/ │ ├── main.tf │ └── variables.tf └── tests/ # Terratest files └── module_test.go AWS VPC Module Example main.tf: resource "aws_vpc" "main" { cidr_block = var.cidr_block enable_dns_hostnames = var.enable_dns_hostnames enable_dns_support = var.enable_dns_support tags = merge( { Name = var.name } , var.tags ) } resource "aws_subnet" "private" { count = length(var.private_subnet_cidrs) vpc_id = aws_vpc.main.id cidr_block = var.private_subnet_cidrs [ count.index ] availability_zone = var.availability_zones [ count.index ] tags = merge( { Name = " $ { var . name } -private- $ { count . index + 1 } " Tier = "private" } , var.tags ) } resource "aws_internet_gateway" "main" { count = var.create_internet_gateway ? 1 : 0 vpc_id = aws_vpc.main.id tags = merge( { Name = " $ { var . name } -igw" } , var.tags ) } variables.tf: variable "name" { description = "Name of the VPC" type = string } variable "cidr_block" { description = "CIDR block for VPC" type = string validation { condition = can(regex( "^([0-9]{1,3}\.){3}[0-9]{1,3}/[0-9]{1,2}$" , var.cidr_block)) error_message = "CIDR block must be valid IPv4 CIDR notation." } } variable "availability_zones" { description = "List of availability zones" type = list(string) } variable "private_subnet_cidrs" { description = "CIDR blocks for private subnets" type = list(string) default = [ ] } variable "enable_dns_hostnames" { description = "Enable DNS hostnames in VPC" type = bool default = true } variable "tags" { description = "Additional tags" type = map(string) default = { } } outputs.tf: output "vpc_id" { description = "ID of the VPC" value = aws_vpc.main.id } output "private_subnet_ids" { description = "IDs of private subnets" value = aws_subnet.private [ * ] .id } output "vpc_cidr_block" { description = "CIDR block of VPC" value = aws_vpc.main.cidr_block } Best Practices Use semantic versioning for modules Document all variables with descriptions Provide examples in examples/ directory Use validation blocks for input validation Output important attributes for module composition Pin provider versions in versions.tf Use locals for computed values Implement conditional resources with count/for_each Test modules with Terratest Tag all resources consistently Module Composition module "vpc" { source = "../../modules/aws/vpc" name = "production" cidr_block = "10.0.0.0/16" availability_zones = [ "us-west-2a" , "us-west-2b" , "us-west-2c" ] private_subnet_cidrs = [ "10.0.1.0/24" , "10.0.2.0/24" , "10.0.3.0/24" ] tags = { Environment = "production" ManagedBy = "terraform" } } module "rds" { source = "../../modules/aws/rds" identifier = "production-db" engine = "postgres" engine_version = "15.3" instance_class = "db.t3.large" vpc_id = module.vpc.vpc_id subnet_ids = module.vpc.private_subnet_ids tags = { Environment = "production" } } Reference Files assets/vpc-module/ - Complete VPC module example assets/rds-module/ - RDS module example references/aws-modules.md - AWS module patterns references/azure-modules.md - Azure module patterns references/gcp-modules.md - GCP module patterns Testing // tests/vpc_test.go package test import ( "testing" "github.com/gruntwork-io/terratest/modules/terraform" "github.com/stretchr/testify/assert" ) func TestVPCModule ( t * testing . T ) { terraformOptions := & terraform . Options { TerraformDir : "../examples/complete" , } defer terraform . Destroy ( t , terraformOptions ) terraform . InitAndApply ( t , terraformOptions ) vpcID := terraform . Output ( t , terraformOptions , "vpc_id" ) assert . NotEmpty ( t , vpcID ) }