Terraform on AWS EC2 (Ubuntu) - Complete Guide

---

What is Terraform?

Terraform is an open-source Infrastructure as Code (IaC) tool developed by HashiCorp. It allows you to define, provision, and manage cloud infrastructure using a declarative language called HCL (HashiCorp Configuration Language).

---

Why Use Terraform?

• Automates infrastructure deployment
• Supports multi-cloud (AWS, Azure, GCP)
• Infrastructure as Code (IaC) - version controlled
• Enables modular, reusable configurations
• Manages resource dependencies and lifecycle
• Safe plan/apply/destroy workflows

---

How to Install Terraform on Ubuntu (EC2)

Step 1: SSH into your EC2 instance

ssh -i "your-key.pem" ubuntu@your-ec2-public-ip
# Installing Terraform and AWS CLI on Ubuntu EC2

---

## 🚀 Install Terraform on Ubuntu

### Step 1: Update packages and install dependencies

```bash
sudo apt-get update && sudo apt-get install -y gnupg software-properties-common curl

Step 2: Add HashiCorp GPG key

curl -fsSL https://apt.releases.hashicorp.com/gpg | sudo gpg --dearmor -o /usr/share/keyrings/hashicorp-archive-keyring.gpg

Step 3: Add official HashiCorp repository

echo "deb [signed-by=/usr/share/keyrings/hashicorp-archive-keyring.gpg] https://apt.releases.hashicorp.com $(lsb_release -cs) main" | sudo tee /etc/apt/sources.list.d/hashicorp.list

Step 4: Install Terraform

sudo apt-get update && sudo apt-get install terraform -y

Step 5: Verify installation

terraform -version

---

☁️ Install and Configure AWS CLI (v2) on Ubuntu EC2

Step 1: Install unzip

sudo apt install unzip -y

Step 2: Download AWS CLI v2 installer

curl "https://awscli.amazonaws.com/awscli-exe-linux-x86_64.zip" -o "awscliv2.zip"

Step 3: Unzip and install

unzip awscliv2.zip
sudo ./aws/install

Step 4: Verify installation

aws --version

Step 5: Configure AWS CLI

aws configure

Enter the following:

• AWS Access Key ID
• AWS Secret Access Key
• Default region (e.g. ap-south-1)
• Output format (e.g. json)

---

✅ Confirm AWS is Configured

Run the following:

aws sts get-caller-identity

Expected output:

{
  "UserId": "AIDAEXAMPLE",
  "Account": "123456789012",
  "Arn": "arn:aws:iam::123456789012:user/your-username"
}

---

🛠 Other Helpful AWS CLI Commands

aws s3 ls
aws configure get region
cat ~/.aws/credentials
cat ~/.aws/config

🛠 Main Terraform Commands with Examples and Use Cases

---

1. terraform init

Initializes a new or existing Terraform project. It downloads all necessary provider plugins.

terraform init

---

2. terraform plan

Creates an execution plan showing what Terraform will do. No resources are changed.

terraform plan

Use Case: Review infrastructure changes before applying them.

---

3. terraform apply

Executes the actions proposed in the plan and creates/updates infrastructure.

terraform apply

Use Case: Deploy or update resources as per your Terraform configuration.

---

4. terraform destroy

Removes all resources defined in your Terraform configuration.

terraform destroy

Use Case: Clean up resources to avoid costs or reset environments.

---

5. terraform validate

Checks whether configuration files are syntactically valid.

terraform validate

Use Case: Ensure configuration correctness before planning or applying.

---

6. terraform fmt

Formats Terraform configuration files to a canonical style.

terraform fmt

Use Case: Maintain consistent formatting and readability in .tf files.

---

☁️ Terraform Remote Backend - In Detail

---

🔍 What is a Remote Backend?

A remote backend allows you to store Terraform's state file in a remote location like S3, enabling team collaboration, locking, and better disaster recovery.

---

✅ Why Use Remote Backend?

• Share state across teams for collaborative deployments
• Lock state files using services like DynamoDB to avoid conflicts
• Secure and reliable disaster recovery
• Prevent local file loss or corruption

---

📦 Example: S3 as Remote Backend

Add the following terraform block in your main configuration (main.tf):

terraform {
  backend "s3" {
    bucket         = "my-terraform-state-bucket"
    key            = "prod/terraform.tfstate"
    region         = "ap-south-1"
    dynamodb_table = "terraform-lock-table"
    encrypt        = true
  }
}

---

🧱 Steps to Set Up S3 Backend with DynamoDB Locking

Step 1: Create the S3 bucket

aws s3 mb s3://my-terraform-state-bucket

Step 2: Enable versioning on the S3 bucket

aws s3api put-bucket-versioning --bucket my-terraform-state-bucket --versioning-configuration Status=Enabled

Step 3: Create DynamoDB table for state locking

aws dynamodb create-table \
  --table-name terraform-lock-table \
  --attribute-definitions AttributeName=LockID,AttributeType=S \
  --key-schema AttributeName=LockID,KeyType=HASH \
  --billing-mode PAY_PER_REQUEST

Step 4: Run terraform init to use the remote backend

terraform init

Terraform will prompt you to migrate local state to remote.

---

📝 Final Notes

• ✅ Always commit your .tf files
• 🚫 Never commit .tfstate or .tfstate.backup files
• 📁 Use .gitignore to exclude sensitive files
• 🔐 Use IAM roles or profiles to securely access AWS credentials in production