Terraform Modules and State

Modules help you organize Terraform configuration into reusable components.

Create a simple module

In modules/storage/main.tf:

resource "aws_s3_bucket" "bucket" {
  bucket = var.bucket_name
  acl    = "private"
}
 
variable "bucket_name" {
  type = string
}

Use the module from root configuration:

module "storage" {
  source      = "./modules/storage"
  bucket_name = "shellrag-storage-demo"
}

Terraform state

Terraform stores state in terraform.tfstate. The state file tracks real infrastructure and lets Terraform compare desired state against actual state.

Common state commands:

terraform show
terraform state list
terraform state rm aws_s3_bucket.website

Remote state

For teams, store state remotely using supported backends like S3, Azure Blob Storage, or Terraform Cloud.

Example backend:

terraform {
  backend "s3" {
    bucket = "shellrag-terraform-state"
    key    = "terraform.tfstate"
    region = "us-east-1"
  }
}

Best practices

• Keep state secure and versioned
• Use modules for reusable patterns
• Use terraform fmt to format files
• Review terraform plan before applying

Modules and state are the foundations of scalable Terraform usage.