Terraform for AWS Services

Prerequisties

Installation

Install latest terraform CLI:

First, dowload the pre-compiled binary package or any appropiate package from the source. Now, unzip and move it to /usr/local/bin path.
```
$ unzip terraform.zip
$ mv ~/Downloads/terraform /usr/local/bin/
```
Verify the installation:
```
$ terraform -help
```

Install AWS CLI V2(For Linux):

To install latest version of AWS CLI, use commands as follows:

$ curl "https://awscli.amazonaws.com/awscli-exe-linux-x86_64.zip" -o "awscliv2.zip"
$ unzip awscliv2.zip
$ sudo ./aws/install

Create an AWS account:

Now, create an aws account following link.We will use the secret credentials of this aws account to interact with AWS Services.

Use AWS credentials:

There are two ways to use aws credentials.

First is, directly using with terraform files which exposes the credentials when files are shared or pushed to pubic repositories.

    provider "aws" {
        access_key = "AKIAIOSFODNN7EXAMPLE"
        secret_key = "wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY"
        region = "us-west-2"
    }

Therefore, to avoid such situation we will configure basic AWS CLI settings to interact with AWS.

$ aws configure --profile terraform-user
AWS Access Key ID [None]: AKIAIOSFODNN7EXAMPLE
AWS Secret Access Key [None]: wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY
Default region name [None]: us-west-2
Default output format [None]: json

The configuration process stores your credentials with a profile name in a file at ~/.aws/credentials. Now, use this profile with terraform files:

    provider "aws" {
        profile = "terraform-user"
        region = "us-west-2"
    }

Terraform Steps

Create Directory

The set of files with .tf extension is used to describe infrastructure in Terraform, which is called Terraform configuration. Each Terraform configuration must be inside its working directory, so create one first.
```
$ mkdir terraform-demo
```

Write Cofiguration

Now, inside the directory create a Terraform file to define your infrastructure.

$ cd terraform-demo
$ touch main.tf

For quick example, we will create a AWS EC2 instance as an infrastructure here. Therefore, paste below configuration in main.tf. It is basic configuration with default network settings (default vpc, default public subnet and randomly generated default security group).

terraform {
required_providers {
    aws = {
    source  = "hashicorp/aws"
    version = "~> 3.36"
    }
}
}
provider "aws" {
profile = "terraform-user"
region  = "us-west-2"
}

resource "aws_instance" "app_server" {
ami           = "ami-830c94e3"
instance_type = "t2.micro"

tags = {
    "Name" = "EC2-By-Terraform"
    "Environment" = "demo-purpose"
}
}

Note:

* terraform {} block contains Terraform settings, including provisioner settings.
* provider {} block configures the specific provider/plugin (aws here) settings to provision/manage your resources.
* resource {} blocks define different component of your infrastucture.
* tags {} block defined inside resource block {} attach tags to that resource when provisioned.

Initialize Directory

Now, initialize the directory with terraform init to download and install the provider which is aws here in hidden directory .terraform.
```
$ terraform init
```
Now, make sure the configuration is syntatically valid before creating the infrastructure:
```
$ terraform validate
Success! The configuration is valid.
```
Create Infrastructure

Now, apply the configuration using command terraform apply to create the infrastructure from the configuration file.
```
$ terraform apply 
```
Inspect State

After applying configuration, Terraform stores the properties and values of the newly created infrastructure in a file terraform.tfstate, such that it can update or destroy those resources whenever needed. You can inspect the current state running command:
```
$ terraform show
```
Destrory Infrastructure

The terraform destroy command destroys the infrastruce resources created using Terraform configuration.
```
$ terraform destroy 
```

Useful Links:

Terraform Official Documentation

limbuu/terraform-for-aws-services

Terraform for AWS Services

Prerequisties

Installation

Terraform Steps