Welcome back to the series of Deploying On AWS Cloud Using Terraform 👨🏻‍💻. In this entire series, we will focus on our core concepts of Terraform by launching important basic services from scratch which will take your infra-as-code journey from beginner to advanced. This series would start from beginner to advance with real life Usecases and Youtube Tutorials.

If you are a beginner for Terraform and want to start your journey towards infra-as-code developer as part of your devops role buckle up 🚴‍♂️ and lets get started and understand core Terraform concepts by implementing it...🎬

❗️❗️Pre-Requisite❗️❗️

1️⃣ Deploying On AWS Cloud Using Terraform Series Pre-Requisites

2️⃣ Deploy VPC, IGW & Associate [Mandatory]

3️⃣ Deploy only public subnet template from the below blog [Mandatory]

4️⃣ Terraform Naming Conventions & Best Practices

🔎Basic Terraform Configurations🔍

As part of basic configuration we are going to setup 3 terraform files

1. Providers File:- Terraform relies on plugins called "providers" to interact with cloud providers, SaaS providers, and other APIs.
   Providers are distributed separately from Terraform itself, and each provider has its own release cadence and version numbers.
   The Terraform Registry is the main directory of publicly available Terraform providers, and hosts providers for most major infrastructure platforms. Each provider has its own documentation, describing its resource types and their arguments.
   We would be using AWS Provider for our terraform series. Make sure to refer Terraform AWS documentation for up-to-date information.
   Provider documentation in the Registry is versioned; you can use the version menu in the header to change which version you're viewing.

    provider "aws" { 
    region = "var.AWS_REGION" 
    shared_credentials_file = "<Your AWS Credentials File path>" 
    }
   

2. Variables File:- Terraform variables lets us customize aspects of Terraform modules without altering the module's own source code. This allows us to share modules across different Terraform configurations, reusing same data at multiple places.
   When you declare variables in the root terraform module of your configuration, you can set their values using CLI options and environment variables. When you declare them in child modules, the calling module should pass values in the module block.

    variable "AWS_REGION" { 
    default = "us-east-1" 
    } 
    data "aws_vpc" "GetVPC" { 
    filter { 
        name = "tag:Name" 
        values = ["CustomVPC"] 
        } 
    } 
    data "aws_subnet" "GetPublicSubnet" { 
    filter { 
        name = "tag:Name" 
        values = ["PublicSubnet1"] 
        } 
    }
   

3. Versions File:- It's always a best practice to maintain a version file where you specific version based on which your stack is testing and live on production.

    terraform { 
    required_version = ">= 0.12" 
    }
   

🎨 Diagrammatic Representation 🎨

Configure AWS Key Pair For EC2

Let's start with creating AWS Key Pair using terraform. First, let's create a file called “ec2_key_pair.tf”, and add the following code.

# Below Code will generate a secure private key with encoding
resource "tls_private_key" "key_pair" {
  algorithm = "RSA"
  rsa_bits  = 4096
}
# Create the Key Pair
resource "aws_key_pair" "key_pair" {
  key_name   = "linux-key-pair"  
  public_key = tls_private_key.key_pair.public_key_openssh
}
# Save file
resource "local_file" "ssh_key" {
  filename = "${aws_key_pair.key_pair.key_name}.pem"
  content  = tls_private_key.key_pair.private_key_pem
}

Configure Security Group For EC2

This method acts as a virtual firewall to control your inbound and outbound traffic flowing to your EC2 instances inside a subnet.

🔳 Resource

✦ aws_security_group:- This resource is define traffic inbound and outbound rules on the subnet level.

🔳 Arguments

✦ name:- This is an optional argument to define name of the security group.
✦ description:- This is an optional argument to mention details about security group that we are creating.
✦ vpc_id:- This is a mandatory argument and refers to id of a VPC to which it would be associated.
✦ tags:- One of the most important property used in all resources. Always make sure to attach tags for all your resources.

EGRESS & INGRESS are processed in attribute-as-blocks mode.

resource "aws_security_group" "ec2_sg" {
  name        = "allow_http"
  description = "Allow http inbound traffic"
  vpc_id      = data.aws_vpc.GetVPC.id

  ingress {
    from_port   = 443
    to_port     = 443
    protocol    = "tcp"
    cidr_blocks = ["0.0.0.0/0"]
  }

  ingress {
    from_port   = 80
    to_port     = 80
    protocol    = "tcp"
    cidr_blocks = ["0.0.0.0/0"]
  }

  egress {
    from_port       = 0
    to_port         = 0
    protocol        = "-1"
    cidr_blocks     = ["0.0.0.0/0"]
  }
  tags = {
    Name = "terraform-ec2-security-group"
  }
}

Configure EC2 Instance With Security Group & Key Pair

🔳 Resource

✦ aws_instance:- This resource is define traffic inbound and outbound rules on subnet level.

🔳 Arguments

✦ ami:- This is a mandatory argument to mention ami id based on which EC2 instance will be launched.
✦ instance_type:- This is a mandatory argument to mention instance type for the EC2 instances like t2.small, t2.micro etc.
✦ security_groups:- This is an optional argument to mention which controls your inbound and outbound traffic flowing to your EC2 instances inside a subnet.
✦ subnet_id:- This is an optional argument to mention EC2 will part of which subnet.
✦ key_name:- This is an optional argument to define to enable ssh connection to your EC2 instance.
✦ tags:- One of the most important property used in all resources. Always make sure to attach tags for all your resources.

resource "aws_instance" "webservers" {
    ami = "ami-0742b4e673072066f"
    instance_type = "t2.micro"
    security_groups = [aws_security_group.ec2_sg.id]
    subnet_id = [data.aws_subnet.GetSubnet]
    key_name = aws_key_pair.key_pair.key_name
    tags = {
      Name = "Linux"
      Env = "Dev"
    }
}

Configure EC2 Instance With Security Group & Userdata

🔳 Resource

✦ aws_instance:- This resource is define traffic inbound and outbound rules on the subnet level.

🔳 Arguments

✦ ami:- This is a mandatory argument to mention ami id based on which EC2 instance will be launched.
✦ instance_type:- This is a mandatory argument to mention instance type for the EC2 instances like t2.small, t2.micro etc.
✦ security_groups:- This is an optional argument to mention that control your inbound and outbound traffic flowing to your EC2 instances inside a subnet.
✦ subnet_id:- This is an optional argument to mention EC2 will part of which subnet.
✦ key_name:- This is an optional argument to define to enable ssh connection to your EC2 instance.
✦ user_data:- This is an optional argument to provide commands or scripts to be executed during the launch of the EC2 instance.
✦ tags:- One of the most important property used in all resources. Always make sure to attach tags for all your resources.

resource "aws_instance" "webservers" {
    ami = "ami-0742b4e673072066f"
    instance_type = "t2.micro"
    security_groups = [aws_security_group.ec2_sg.id]
    subnet_id = [data.aws_subnet.GetSubnet]
    key_name = aws_key_pair.key_pair.key_name
    user_data = <<EOF
    #! /bin/bash
    sudo su
    sudo yum update
    sudo yum install -y httpd
    sudo chkconfig httpd on
    sudo service httpd start
    echo "<h1>Deployed EC2 With Terraform</h1>" | sudo tee /var/www/html/index.html
    EOF

    tags = {
      Name = "Linux"
      Env = "Dev"
    }
}

Configure EC2 Instance With Userdata & Variable Mapping

First, let's create a variable with a type map where we will define for which region we are going to use which specific AMI[Amazon Machine Image]. Define this configuration in vars.tf

variable "AWS_REGION" { 
    default = "us-east-1" 
} 
variable "ami" { 
type = map 
default = { 
    "us-east-1" = "ami-04169656fea786776" 
    "us-west-1" = "ami-006fce2a9625b177f" 
    } 
}

Now let's see how we can perform a lookup on this map based on region.

resource "aws_instance" "webservers" { 
    ami = lookup(var.ami,var.AWS_REGION) 
    instance_type = "t2.micro" 
    security_groups = [aws_security_group.ec2_sg.id] 
    subnet_id = [data.aws_subnet.GetSubnet] 
    key_name = aws_key_pair.key_pair.key_name 
    user_data = <<EOF
    #! /bin/bash
    sudo su
    sudo yum update
    sudo yum install -y httpd
    sudo chkconfig httpd on
    sudo service httpd start
    echo "<h1>Deployed EC2 With Terraform</h1>" | sudo tee /var/www/html/index.html
    EOF

    tags = { 
    Name = "Environment" 
    Env = "Dev" 
    } 
}

🔊To view the entire GitHub code click here

1️⃣ The terraform fmt command is used to rewrite Terraform configuration files to a canonical format and style👨‍💻.

 terraform fmt

2️⃣ Initialize the working directory by running the command below. The initialization includes installing the plugins and providers necessary to work with resources. 👨‍💻

terraform init

3️⃣ Create an execution plan based on your Terraform configurations. 👨‍💻

terraform plan

4️⃣ Execute the execution plan that the terraform plan command proposed. 👨‍💻

terraform plan -auto-approve

👁‍🗨👁‍🗨 YouTube Tutorial 📽

[Coming Soon]

❗️❗️Important Documentation❗️❗️

⛔️ Hashicorp Terraform
⛔️ AWS CLI
⛔️ Hashicorp Terraform Extension Guide
⛔️ Terraform Autocomplete Extension Guide
⛔️ AWS Security Group
⛔️ AWS Key Pair
⛔️ AWS EC2

🥁🥁 Conclusion 🥁🥁

In this blog, we have configured the below resources
✦ AWS Key Pair.
✦ AWS Security Group for the EC2 instances which need to be provisioned inside subnets we have launched.
✦ AWS EC2 With User Data.
✦ AWS EC2 With Mapping Variable.
I have also referenced what arguments and documentation we are going to use so that while you are writing the code it would be easy for you to understand terraform official documentation. Stay with me for the next blog where we will be doing deep dive into Target Group, Elastic Load Balancer & ELB Listener Using Terraform.

📢 Stay tuned for my next blog.....

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