Scaling With Terraform

Hey Learners! Welcome back. In the few last challenges, we launched our first static web page on the Apache server in a new VPC and created and managed S3 Buckets using Terraform. Moving forward we'll scale our infrastructure. We all know how to scale manually using AWS console but in this challenge, we'll do it with the help of Terraform. Let's scale it...

Scaling:-

Scaling is the process of adding or removing resources to match the changing demands of your application. As your application grows, you will need to add more resources to handle the increased load. And as the load decreases, you can remove the extra resources to save costs.

To know more about Auto Scaling Group in AWS and how to create manually by AWS console check out the DAY40 challenge.

Pre-requisite:- Read and understand the Day40 challenge so that you'll get a clear picture of ASG.

Steps:-

Create a Security Group
Create a Template for an EC2 Auto Scaling Group with user_data
Create Auto-Scaling Group
Apply the configuration
Validate

1- Create a Security Group

Create a Security Group as shown below

provider "aws" {
region = "ap-south-1"
}

resource "aws_security_group" "MySG" {
  name_prefix = "SG-ASG"
  ingress {
    from_port = 80
    to_port = 80
    protocol = "tcp"
    cidr_blocks = ["0.0.0.0/0"]
  }

  ingress {
    from_port = 22
    to_port = 22
    protocol = "tcp"
    cidr_blocks = ["0.0.0.0/0"]
  }

  ingress {
    from_port = 443
    to_port = 443
    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"]
  }
}

2- Create a Template for an EC2 Auto Scaling Group with user_data

For EC2 Auto Scaling Group we have to create Launch Configuration which is an instance configuration template that an Auto Scaling Group uses to launch EC2 instances.

In Terraform we create configuration files as shown below for Templates for an EC2 Auto Scaling Group

resource "aws_launch_configuration" "ASG" {
  name_prefix = "testingASG"
  image_id = "ami-0f5ee92e2d63afc18"
  instance_type = "t2.micro"
  security_groups = [aws_security_group.MySG.id]
  user_data = <<-EOF
        #!/bin/bash
        sudo apt-get update -y
        sudo apt-get install nginx -y
        sudo systemctl start nginx
        echo "Welcome to my website created by Terraform!" > /var/www/html/index.html
        sudo systemctl restart nginx
        sudo systemctl enable nginx
        EOF
}

3- Create Auto-Scaling Group(ASG)

Create an ASG as shown below

resource "aws_autoscaling_group" "testgrp" {
  name = "testgrp"
  launch_configuration = aws_launch_configuration.ASG.name
  min_size = 1
  max_size = 3
  desired_capacity = 2
  health_check_type = "EC2"
  vpc_zone_identifier = ["subnet-057f98bc012758e0d"] #replace subnet as per your VPC
}

The whole main.tf will look like

provider "aws" {
region = "ap-south-1"
}

resource "aws_security_group" "MySG" {
  name_prefix = "SG-ASG"
  ingress {
    from_port = 80
    to_port = 80
    protocol = "tcp"
    cidr_blocks = ["0.0.0.0/0"]
  }

  ingress {
    from_port = 22
    to_port = 22
    protocol = "tcp"
    cidr_blocks = ["0.0.0.0/0"]
  }

  ingress {
    from_port = 443
    to_port = 443
    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"]
  }
}

resource "aws_launch_configuration" "ASG" {
  name_prefix = "testingASG"
  image_id = "ami-0f5ee92e2d63afc18"
  instance_type = "t2.micro"
  security_groups = [aws_security_group.MySG.id]
  user_data = <<-EOF
        #!/bin/bash
        sudo apt-get update -y
        sudo apt-get install nginx -y
        sudo systemctl start nginx
        echo "Welcome to my website created by Terraform!" > /var/www/html/index.html
        sudo systemctl restart nginx
        sudo systemctl enable nginx
        EOF
}

resource "aws_autoscaling_group" "testgrp" {
  name = "testgrp"
  launch_configuration = aws_launch_configuration.ASG.name
  min_size = 1
  max_size = 3
  desired_capacity = 2
  health_check_type = "EC2"
  vpc_zone_identifier = ["subnet-057f98bc012758e0d"]      #replace subnet as per your VPC
}

4- Apply the configuration

Use the terraform apply command to apply the changes

5- Validate

Go to the AWS console. Choose Auto Scaling Group from the left navigation bar in the EC2 service. Check the details for ASG.

Choose EC2 service and make sure 2 new instances are added. Copy the PublicIP of both and check whether a web page is hosted or not as per user_data.

Check for the second instance.

We successfully created ASG. Let's test ASG.

Task 2- Test Scaling

Go to the AWS console. Select Auto Scaling Group from the left navigation pane. Select ASG as listed. Edit the Group details. Make the Desired capacity as 3 and save the changes.