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IaC Terraform 50 guides · updated 2026

Infrastructure as code done right — providers, state, reusable modules, and the workflow patterns that keep multi-cloud deployments sane in 2026.

Terraform Registry

The Terraform Registry is the central hub for discovering and sharing Terraform providers and modules. Instead of writing every piece of infrastructure from scratch, you can use battle-tested community modules for common patterns like VPCs, EKS clusters, and RDS databases.

What’s on the Registry

Providers — 3,000+ provider plugins for connecting to cloud APIs:

Modules — reusable infrastructure components:

Using Public Registry Modules

# AWS VPC — most popular Terraform module with 80M+ downloads
module "vpc" {
  source  = "terraform-aws-modules/vpc/aws"
  version = "~> 5.8"


  name = "production-vpc"
  cidr = "10.0.0.0/16"


  azs             = ["us-east-1a", "us-east-1b", "us-east-1c"]
  private_subnets = ["10.0.1.0/24", "10.0.2.0/24", "10.0.3.0/24"]
  public_subnets  = ["10.0.101.0/24", "10.0.102.0/24", "10.0.103.0/24"]


  enable_nat_gateway   = true
  single_nat_gateway   = false   # One NAT GW per AZ for HA
  enable_dns_hostnames = true


  tags = {
    Environment = "production"
    ManagedBy   = "terraform"
  }
}


# Reference module outputs
resource "aws_instance" "app" {
  subnet_id = module.vpc.private_subnets[0]
}

EKS Cluster via Registry Module

module "eks" {
  source  = "terraform-aws-modules/eks/aws"
  version = "~> 20.0"


  cluster_name    = "production-eks"
  cluster_version = "1.30"


  vpc_id                         = module.vpc.vpc_id
  subnet_ids                     = module.vpc.private_subnets
  cluster_endpoint_public_access = true


  eks_managed_node_groups = {
    general = {
      instance_types = ["m6i.large"]
      min_size       = 2
      max_size       = 10
      desired_size   = 3
    }
    gpu = {
      instance_types = ["g5.xlarge"]
      min_size       = 0
      max_size       = 4
      desired_size   = 0
      taints = [{
        key    = "nvidia.com/gpu"
        value  = "true"
        effect = "NO_SCHEDULE"
      }]
    }
  }


  tags = local.common_tags
}

RDS Module

module "rds_postgres" {
  source  = "terraform-aws-modules/rds/aws"
  version = "~> 6.6"


  identifier = "production-postgres"
  engine     = "postgres"
  engine_version = "16.3"
  instance_class = "db.r6g.large"
  allocated_storage = 100
  storage_type      = "gp3"
  storage_encrypted = true


  db_name  = "appdb"
  username = "dbadmin"
  manage_master_user_password = true   # Secrets Manager integration


  multi_az               = true
  publicly_accessible    = false
  vpc_security_group_ids = [aws_security_group.rds.id]
  db_subnet_group_name   = aws_db_subnet_group.main.name


  backup_retention_period    = 7
  backup_window              = "03:00-06:00"
  maintenance_window         = "Mon:00:00-Mon:03:00"
  deletion_protection        = true
  skip_final_snapshot        = false
  final_snapshot_identifier  = "production-postgres-final"


  tags = local.common_tags
}

Finding Modules on the Registry

Visit registry.terraform.io/modules and filter by:

Terminal window
# Search via CLI (requires Terraform 1.x)
terraform providers search aws


# Or use the web interface and copy the use block:
module "example" {
  source  = "terraform-aws-modules/vpc/aws"
  version = "5.8.1"
  # ...
}

Module Source Types

The Registry is just one of several module source locations:

# Terraform Registry (official)
source = "terraform-aws-modules/vpc/aws"


# GitHub (public repository)
source = "github.com/my-org/terraform-modules//vpc"


# GitHub with specific tag/branch
source = "github.com/my-org/terraform-modules//vpc?ref=v1.2.0"


# Private Git (with SSH)
source = "git::ssh://git@github.com/my-org/private-modules.git//vpc?ref=v2.0.0"


# Local path (same repo)
source = "./modules/vpc"
source = "../shared/modules/networking"


# Terraform Cloud Private Registry
source = "app.terraform.io/my-org/vpc/aws"


# S3 bucket (uncommon)
source = "s3::https://s3-us-west-2.amazonaws.com/acme-terraform-modules/vpc/1.0.0.zip"

Evaluating Registry Modules

Before using a community module, check:

SignalWhat to Look For
Verified badgeModule maintained by a HashiCorp Technology Partner
Download count1M+ downloads suggests battle-tested
Last publishedUpdated in last 6 months = actively maintained
GitHub starsCommunity confidence indicator
Open issues/PRsHigh count of unresolved issues is a warning sign
LicenseMIT or Apache 2.0 for commercial use
Terminal window
# Review what a module will create before using
# Clone and inspect the module source
git clone https://github.com/terraform-aws-modules/terraform-aws-vpc
cat terraform-aws-vpc/main.tf  # Review all resources the module creates

Private Module Registry

For internal modules used across your organization, Terraform Cloud/Enterprise provides a private registry:

# Internal module from Terraform Cloud private registry
module "internal_vpc" {
  source  = "app.terraform.io/my-company/vpc/aws"
  version = "~> 2.0"
}

For open-source alternatives, host modules in a git monorepo and reference by path and git tag.