Skip to main content Build reusable Terraform modules for AWS, Azure, and GCP infrastructure following infrastructure-as-code best practices. Use when creating infrastructure modules, standardizing cloud provisioning, or implementing reusable IaC components.
npx skills add wshobson/agents --skill terraform-module-library agents claude claude-code subagents anthropic automation
Terraform Module Library
Production-ready Terraform module patterns for AWS, Azure, GCP, and OCI infrastructure.
Purpose
Create reusable, well-tested Terraform modules for common cloud infrastructure patterns across multiple cloud providers.
When to Use
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/
└── oci/
├── vcn/
├── oke/
└── object-storage/
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 = "${var.name}-igw"
},
var.tags
)
}
variable "name" {
description = "Name of the VPC"
type = string
}
variable "cidr_block" {
description = "CIDR block for VPC"
type = string
validation {
condition = can(regex("^([0-9]{1,3}\\.){3}[0-9]{1,3}/[0-9]{1,2}$", 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 = {}
}
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
Reference: See references/aws-modules.md and references/oci-modules.md
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"
}
}
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)
}
Related Skills
multi-cloud-architecture - For architectural decisions
cost-optimization - For cost-effective designs
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Create or update AgentSkills. Use when designing, structuring, or packaging skills with scripts, references, and assets.
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CLI to manage emails via IMAP/SMTP. Use `himalaya` to list, read, write, reply, forward, search, and organize emails from the terminal. Supports multiple accounts and message composition with MML (MIME Meta Language).