Terraform Command Basics

Step-01: Terraform configuration files

• Terraform uses declarative syntax to describe your Infrastructure as Code (IaC) infrastructure and then persist it in configuration files that can be shared, reviewed, edited, versioned, preserved, and reused.
• Terraform configuration files can use either of two formats: Terraform domain-specific language (HashiCorp Configuration Language format [HCL]), which is the recommended approach, or JSON format if the files need to be machine-readable.
• Configuration files that use the HCL format end with the .tf file extension;
• Those using JSON format end with the .tf.json file extension.
• The Terraform format is human-readable, while the JSON format is machine readable

Step-01: Introduction to Terraform workflow - main commands

Terraform init: - Used to initialize a working directory containing terraform config files. - This is the first command that should be run after writing a new terraform configuration file. - It downloads providers and modules Terraform validate: - Validates the configuration files in the respective directory to ensure that they are syntactically valid and internally consistent. Terraform plan: - Creates an execution plan - Terraform performs a refresh and determines what actions are necessary to achieve the desired state specified in the configuration files Terraform apply: - Used to apply the changes required to reach the desired state of the configuration - By default, apply scans the current directory for the configuration and applies the changes appropriately. - The state file is created when apply is ran the first time. Terraform destroy: - Use to destroy terraform managed infrastructure. - This will ask for confirmation before destroying.

Step-02: Review terraform manifest for EC2 Instance

• Pre-Conditions-1: Ensure you have default-vpc in that respective region
• Pre-Conditions-2: Ensure AMI you are provisioning exists in that region if not update AMI ID
• Pre-Conditions-3: Verify your AWS Credentials in $HOME/.aws/credentials

# Terraform Settings Block
terraform {
  required_version = "~> 1.0"
  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = "~> 3.0"            # Optional but recommended in production
    }
  }
}

# Provider Block
provider "aws" {
  profile = "default"
  region  = "us-west-2"
}

# Resource Block
resource "aws_instance" "ec2demo" {
  ami           = "ami-0e5b6b6a9f3db6db8"
  instance_type = "t2.micro"
}

Step-03: Terraform Core Commands

Initialize Terraform

terraform init

Terraform Validate

terraform validate

Terraform Plan to Verify what it is going to create / update / destroy

terraform plan

Terraform Apply to Create EC2 Instance

terraform apply

Step-04: Verify the EC2 Instance in AWS Management Console

• Go to AWS Management Console -> Services -> EC2
• Verify newly created EC2 instance

Step-05: Destroy Infrastructure

Destroy EC2 Instance

terraform destroy