What is Terraform and how to install and use it on AWS EC2

Terraform is the "Infrastructure as Code (IaC)" tool. It is used to build, manage and change infrastructure in a safe and repeatable way.

It is used to manage environments with a configuration language called the HashiCorp Configuration Language (HCL) for human-readable, automated deployments.

Terraform can be used to manage infrastructure on multiple clouds like AWS, GCP and others. Terraform creates a state file which is the source of truth for the resource configurations. This means whenever resources are created this state file is updated with the state of the resources being created. 

In this article we will see the steps to install Terraform on Ubuntu and use it to create a VPC on AWS cloud.

To learn and know more about Terraform click here.

Pre-requisites

1. AWS Account (Create if you don’t have one).
2. An EC2 Instances (Click here to learn to create an EC2 Instance)
3. Root access to the servers.
4. 'access_key' & 'secret_key' of an AWS IAM User. (Click here to learn to create an IAM user with 'access_key' & 'secret_key' on AWS, )

What we will do

1. Install Terraform 
2. Write Terraform configuration files.
3. Create a VPC using the Terraform configuration files
4. Delete the created VPC using Terraform

Install Terraform

Installing Terraform is pretty simple and straight. You can find the suitable package for your system from here.

Before downloading the file let's install the 'wget' and 'unzip' package if not available on the system using the following commands.

apt-get update -y
apt-get install wget unzip -y

Let's create a dedicated directory 'terraform' under '/opt/' where we can download the package

cd /opt/
mkdir terraform
cd terraform/

Download the terraform package using 'wget' command and unzip it.

wget https://releases.hashicorp.com/terraform/0.12.18/terraform_0.12.18_linux_amd64.zip
unzip terraform_0.12.18_linux_amd64.zip
ls -lt

Once you unzip the package you downloaded you will see a binary 'terraform'. Move this binary to /usr/local/bin/.

You can verify if the installation was successful or not using terraform command but checking its version.

mv terraform /usr/local/bin/
terraform -v

Write Terraform configuration files

Create a dedicated directory where you can create terraform configuration files

mkdir terraform
cd terraform/

Use an editor of your choice and copy-paste the following configurations to create variables.tf, terraform.tfvars and  main.tf

Create 'main.tf' which is responsible to create VPC  on to AWS. The following configuration will create a VPC, internet gateway ,route table, availability zone and  security group. This main.tf will read values of variables from variables.tf and terraform.tfvars.

vim main.tf

provider "aws" {
      region     = "${var.region}"
      access_key = "${var.access_key}"
      secret_key = "${var.secret_key}"
}
resource "aws_vpc" "vpc" {
     cidr_block = "10.0.0.0/16"
}
resource "aws_internet_gateway" "gateway" {
     vpc_id = "${aws_vpc.vpc.id}"
}
resource "aws_route" "route" {
     route_table_id         = "${aws_vpc.vpc.main_route_table_id}"
     destination_cidr_block = "0.0.0.0/0"
     gateway_id             = "${aws_internet_gateway.gateway.id}"
}
data "aws_availability_zones" "available" {}
resource "aws_subnet" "main" {
    count                   = "${length(data.aws_availability_zones.available.names)}"
    vpc_id                  = "${aws_vpc.vpc.id}"
    cidr_block              = "10.0.${count.index}.0/24"
    map_public_ip_on_launch = true
    availability_zone       = "${element(data.aws_availability_zones.available.names, count.index)}"
}
resource "aws_security_group" "default" {
     name        = "