Understanding 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.

Terraform makes it easy to scale your infrastructure by providing a declarative way to define your resources. You can define the number of resources you need and Terraform will automatically create or destroy the resources as needed.

Prerequisites

Before proceeding, we have to set up AWS Provider, Region, VPC, InternetGateway, Security Group, and RouteTable.

COPY

📁 terraform/terraform-aws 
    --📄 terraform.tf 
    --📄 provider.tf 
    --📄 vpc.tf
    --📄 subnet.tf 
    --📄 internetgateway.tf 
    --📄 routetable.tf 
    --📄 securitygroup.tf

Create a terraform.tf file to declare AWS providers required for the system.

  terraform {
    required_providers {
      aws = {
        source  = "hashicorp/aws"
        version = "~> 4.0"
      }
    }
  }

Create a provider.tf file to specify the AWS region required for instance.
```
 provider "aws" {
    region = "us-east-1"
  }
```

Create a vpc.tf file to set up VPC for the ec2 instance.

  resource "aws_vpc" "main" {
    cidr_block       = "10.0.0.0/16"
    tags = {
      Name = "main"
    }
  }

Inside subnet.tf file create 2 subnets (public, private) for auto-scaling group.

```apache #public subnet resource "aws_subnet" "public_subnet" { vpc_id = aws_vpc.main.id cidr_block = "10.0.1.0/24"

tags = { Name = "PublicSubnet" } }

private subnet

resource "aws_subnet" "private_subnet" { vpc_id = aws_vpc.main.id cidr_block = "10.0.2.0/24"

tags = { Name = "PrivateSubnet" } }


    ![](https://cdn.hashnode.com/res/hashnode/image/upload/v1703684887315/c9ce9639-1265-4b2d-a4ad-1f08fc0c2c9b.png align="center")

5. Create an [`internetgateway.tf`](https://mizanf123.hashnode.dev/) file to configure the internet gateway.

    ```apache
     resource "aws_internet_gateway" "my_igw" {
       vpc_id = aws_vpc.main.id
       tags = {
         Name = "internet-getway"
       }
     }

Create a routetable.tf file for routing public subnet to VPC.

 resource "aws_route_table" "public" {
     vpc_id = aws_vpc.main.id

     route {
         cidr_block = "0.0.0.0/0"
         gateway_id = aws_internet_gateway.my_igw.id
     }
     tags = {
     Name = "PublicRouteTable"
   }
 }

 resource "aws_route_table_association" "public_subnet" {
     subnet_id      = aws_subnet.public_subnet.id
     route_table_id = aws_route_table.public.id
 }

Create a securitygroup.tf file which will create a security group that allows SSH, HTTP, HTTPS, and egress traffic to the instances.

 resource "aws_security_group" "web_server" {
     name_prefix = "web-server-sg"
     vpc_id = aws_vpc.main.id
     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"]
   }
   egress {
       from_port   = 0
       to_port     = 0
       protocol    = -1
       cidr_blocks = ["0.0.0.0/0"]
   }
   }

Task 1: Create an Auto Scaling Group

Now create a main.tf file. In your main.tf file, add the following code to create an Auto Scaling Group:

    resource "aws_launch_configuration" "web_server_as" {
      image_id           = "ami-053b0d53c279acc90"
      instance_type = "t2.micro"
      security_groups = [aws_security_group.web_server.id]

      user_data = <<-EOF
      #!/bin/bash
      sudo apt-get update -y
      sudo apt-get install apache2 -y
      sudo systemctl start apache2
      sudo systemctl enable apache2
      sudo systemctl restart apache2
      sudo chmod 766 /var/www/html/index.html
      sudo echo "<html><body><h1>Welcome to Terraform Scaling.</h1></body></html>" >/var/www/html/index.html    
     EOF
    }

    resource "aws_elb" "web_server_lb"{
       name = "web-server-lb"
       security_groups = [aws_security_group.web_server.id]
       subnets = [aws_subnet.public_subnet.id,aws_subnet.private_subnet.id]
       listener {
        instance_port     = 8000
        instance_protocol = "http"
        lb_port           = 80
        lb_protocol       = "http"
      }
      tags = {
        Name = "terraform-elb"
      }
    }

    resource "aws_autoscaling_group" "web_server_asg" {
      name                 = "web-server-asg"
      launch_configuration = aws_launch_configuration.web_server_as.name
      min_size             = 1
      max_size             = 3
      desired_capacity     = 2
      health_check_type    = "EC2"
      load_balancers       = [aws_elb.web_server_lb.name]
      vpc_zone_identifier  = [aws_subnet.public_subnet.id]
        tag {
      key                 = "Name"
      value               = "web-server-as"
      propagate_at_launch = true
    }
    }

Apply Your Terraform Configuration

Run terraform apply in the terminal to apply your Terraform configuration.
Type yes

Verify

Once Terraform completes execution, verify that the Auto Scaling Group is created with the desired settings in the AWS Auto Scaling Group dashboard.

Task 2: Test Scaling

Go to the AWS Management Console and select the Auto Scaling Groups service.
Select the Auto Scaling Group you just created and click on the "Edit" button.
Increase the "Desired Capacity" to 3 and click on the "Save" button.
Wait a few minutes for the new instances to be launched. Go to the EC2 Instances service and verify that the new instances have been launched.
Decrease the "Desired Capacity" to 1 and wait a few minutes for the extra instances to be terminated.
Go to the EC2 Instances service and verify that the extra instances have been terminated.

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Scaling with Terraform 🚀

#day62 of #90daysofdevops

Table of contents

Understanding Scaling

Prerequisites

private subnet

Task 1: Create an Auto Scaling Group

Task 2: Test Scaling

Connect with me:)