Designing Reusable Terraform Modules for ContentSphere

In the previous lab, we configured Terraform and the AWS provider.

Now, the ContentSphere platform needs multiple S3 buckets. Instead of writing the same S3 configuration again and again, we will create one reusable Terraform module and use it to create buckets

• Verify Terraform: terraform version — Confirms Terraform is installed.
• Verify AWS: aws sts get-caller-identity — Confirms AWS CLI is configured.
• Go to Project: cd ~/contentsphere-terraform — Opens the Terraform project directory.

Run

Purpose: Creates a separate folder where we will keep our reusable S3 module.

Verify:

ls modules

Expected:

s3

Create the module configuration:vi modules/s3/main.tf

Add:

Purpose

This file contains the actual S3 resource configuration.

Instead of writing the S3 bucket configuration directly in main.tf, we keep it inside the module so that it can be reused.

Create: vi modules/s3/variables.tf

Add: variable "bucket_name" {}

Purpose

The module needs to know what name to give the S3 bucket.

Instead of hardcoding the name inside the module, we create a variable.

bucket_name

     ↓

Module receives bucket name

     ↓

S3 bucket is created

Now we will use the module from the main Terraform configuration.

Open:

vi main.tf

Keep the AWS provider configuration from the previous lab and add:

module "contentsphere_bucket" {

  source = "./modules/s3"

  bucket_name = "contentsphere-demo-12345"

}

Replace:

contentsphere-demo-12345

Purpose

This tells Terraform:

"Use the S3 module located in modules/s3 and create a bucket using this name."

Run: terraform init

Purpose

Terraform needs to prepare the project and download/initialize the required providers and modules.

Because we added a module, Terraform also detects:

./modules/s3

Run: terraform validate

Expected: Success! The configuration is valid.

Purpose

Checks whether our Terraform configuration has syntax or configuration errors before creating anything

Run: terraform plan

Expected: Plan: 1 to add, 0 to change, 0 to destroy.

Purpose

terraform plan shows what Terraform is going to create without actually creating it.

Think of it as: Plan = Preview

Run: terraform apply

Terraform will ask for confirmation.

Enter: yes

Purpose

terraform apply actually creates the infrastructure described in the Terraform configuration.

In this case:

Terraform

   ↓

S3 Module

   ↓

AWS S3 Bucket

Run: aws s3 ls

You should see your bucket:contentsphere-demo-12345

Purpose

This confirms that the S3 bucket was successfully created in AWS

Now we will demonstrate the main benefit of modules.

Open:vi main.tf

Add another module:module "contentsphere_bucket" {

 source = "./modules/s3"

bucket_name = "contentsphere-demo-12345"

}

module "contentsphere_backup" {

  source = "./modules/s3"

  bucket_name = "contentsphere-backup-12345"

}

Use another globally unique bucket name.

Purpose

We are using the same S3 module again instead of writing another S3 resource.

            modules/s3

             /        \

            ↓          ↓

     Application     Backup

       Bucket        Bucket

This demonstrates:

Write once → Reuse multiple times

Run: terraform plan

Purpose: Preview the second S3 bucket before creating it.

You should see something similar to:

Plan: 1 to add, 0 to change, 0 to destroy.

Then run: terraform apply

Enter: yes

Purpose Creates the second S3 bucket using the same reusable module.

Run: aws s3 ls

You should see both buckets: contentsphere-demo-12345

contentsphere-backup-12345

Purpose

Confirms that the same Terraform module successfully created multiple resources.

Run: tree

Expected:

contentsphere-terraform/

├── main.tf

├── modules/

│   └── s3/

│       ├── main.tf

│       └── variables.tf

└── terraform.tfstate

Purpose

This helps you understand how a Terraform project is organized.

main.tf

   ↓

Calls Module

modules/s3/

   ↓

Reusable S3 Configuration

After completing the lab: terraform destroy

Enter: yes

Purpose

Removes the S3 buckets created during the lab so that the AWS resources are not left running unnecessarily.

Great job!

1. Create & Configure: Create a Terraform module, define variables, and pass values to it.
2. Deploy & Reuse: Call the module to create AWS resources and reuse it as needed.
3. Review & Clean Up: Review the module structure and destroy the created resources.