Terraform Basics

Imagine you’re playing with LEGO blocks and want to build a big LEGO city with houses, roads, and parks. But instead of putting the pieces together by hand every time, you can write down instructions so that a robot can build it for you.

Terraform works similarly to that robot.

It's an open-source tool to define and manage the Infrastructure-as-Code (IaC).

You'll be writing the configuration file, and Terraform will apply the instructions provided. These instructions will specify the features of the resources and other relevant details.

Instead of manually setting up servers, databases, networks and other resources you write code to define what you want. This code is written in HashiCorp Configuration Language (HCL).

It works with many cloud providers (like AWS, Google Cloud, Azure) and on-premises data centers.

Images from Terraform documentation

How Terraform works:

1. 

   Open Gitbash or any other similar tool.

2. aws configure This command initiates the AWS CLI configuration process. When you run aws configure, you will be prompted to enter your AWS Access Key ID, Secret Access Key, default region name, and default output format. This sets up your AWS CLI environment to interact with AWS services.

aws configure

3. cd /d This command changes the current directory to the root directory of the D: drive in Windows operating systems. The cd command stands for "change directory" and it is used to navigate between directories in the command line.

cd /d

4. mkdir terraform-examples This command creates a new directory named terraform-examples in your current working directory. The mkdir command stands for "make directory" and it's used to create new directories in Unix-like operating systems.

mkdir terraform-examples

5. mkdir exercise1 This command creates a new directory named exercise1 in your current working directory(terraform-examples).

mkdir exercise1/

6. cd exercise1/ This command changes the current directory to the exercise1 directory within your current working directory.

cd exercise1/

7. vim first_instance.tfThis command opens the file first_instance.tf in the Vim text editor. If the file does not exist, Vim will create a new file with that name.

vim first_instance.tf

8. Inside the terraform file determine this configuration (https://github.com/Ragavi04P/Terraform-Practice/blob/main/first_instance.tf)or similar configuration for which resource you should use.

This Terraform configuration defines an AWS provider and an AWS EC2 instance resource. Here's a brief explanation of each part:

• This block specifies the AWS provider and sets the region to us-east-2.

provider "aws" {
  region = "us-east-2"
}

resource "aws_instance" "intro" {
  ami                    = "ami-03657b56516ab7912"
  instance_type          = "t2.micro"
  availability_zone      = "us-east-2a"
  key_name               = "your key pair name"
  vpc_security_group_ids = ["your sg id"]
  tags = {
    Name    = "sample-Instance"
    Project = "Terraform"
  }
}

• This block defines an AWS EC2 instance resource named intro.

• ami specifies the Amazon Machine Image ID to use for the instance.

• instance_type sets the type of instance to t2.micro.

• availability_zone specifies the availability zone within the region.

• key_name is the name of the key pair to use for SSH access.

• vpc_security_group_ids is a list of security group IDs to associate with the instance.

• tags assigns metadata to the instance, such as Name and Project.

9. terraform init This command initializes a Terraform working directory. It prepares the directory by downloading and installing the necessary provider plugins and setting up the backend configuration. This is the first command that should be run after writing a new Terraform configuration or cloning an existing one from version control.

terraform init

10. terraform fmt This command formats the Terraform configuration files in the current directory to a canonical format and style. It ensures that the code is properly indented and organized, making it easier to read and maintain.

    terraform fmt
    

11. terraform validate This command checks the syntax and validity of the Terraform configuration files in the current directory. It ensures that the configuration is syntactically correct and that all required arguments are specified. This is a useful step to catch errors before applying the configuration.

terraform validate

12. terraform plan This command creates an execution plan, showing what actions Terraform will take to achieve the desired state defined in the configuration files. It compares the current state with the desired state and lists the changes that will be made such as creating, updating, or deleting resources. This allows you to review the proposed changes before applying them.

terraform plan

13. terraform apply This command applies the changes required to reach the desired state of the configuration as defined by the Terraform files. It creates, updates, or deletes infrastructure resources to match the configuration. Before making any changes, Terraform will show a plan of the actions it will take and ask for your confirmation.

terraform apply

This command lists the files and directories in the current working directory.

ls

14. cat terraform.tfstateThis command displays the contents of the terraform.tfstate file in the terminal. The cat command is used to concatenate and display the content of files in Unix-like operating systems. The terraform.tfstate file contains the current state of your infrastructure as managed by Terraform.

cat terraform.tfstate

A state file in Terraform records the current state of your infrastructure, mapping your configuration to real-world resources. It helps Terraform determine what changes need to be applied to reach the desired state. The state file is essential for tracking and managing infrastructure efficiently. The output will be in JSON format.

15. cat terraform.tfstate.backup This command displays the contents of the terraform.tfstate.backup file in the terminal. The terraform.tfstate.backup file is a backup of the state file, which contains the previous state of your infrastructure as managed by Terraform.

cat terraform.tfstate.backup

16. terraform destroy This command is used to destroy the infrastructure managed by Terraform. It will remove all the resources defined in your Terraform configuration files. Before making any changes, Terraform will show a plan of the actions it will take and ask for your confirmation. This is useful for tearing down environments or cleaning up resources that are no longer needed.

terraform destroy

These are the terraform basics that you need to know for setting up the infrastructure for a cloud environment.