Day 68 - Scaling with Terraform 🚀

Welcome to Day 68 of the 90DaysOfDevOpsChallenge! Yesterday, we learned how to create an AWS S3 Bucket with Terraform. Today, we will explore how to scale our infrastructure with Terraform. 🌟

Understanding Scaling

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

Terraform simplifies scaling by providing a declarative way to define your resources. 📝 You specify the number of resources you need, and Terraform handles the creation or destruction of those resources. Let's dive into scaling with Terraform! 🚀

Install Terraform on your local machine.

sudo apt-get update
sudo apt-get install -y gnupg software-properties-common curl
curl -fsSL https://apt.releases.hashicorp.com/gpg | sudo apt-key add -
sudo apt-add-repository "deb [arch=amd64] https://apt.releases.hashicorp.com $(lsb_release -cs) main"
sudo apt-get update
sudo apt-get install terraform
terraform -version

Install AWS CLI:
```
 sudo apt-get update
 sudo snap install aws-cli --classic
 aws --version
 aws configure
```
Task 1: Create an Auto Scaling Group 🔧

Auto Scaling Groups are used to automatically add or remove EC2 instances based on the current demand. Follow these steps to create an Auto Scaling Group:

📝 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-02bf8ce06a8ed6092"
   instance_type   = "t2.micro"
   security_groups = [aws_security_group.web_server.name]

   user_data = <<-EOF
               #!/bin/bash
               echo "<html><body><h1>You're doing really Great</h1></body></html>" > index.html
               nohup python -m SimpleHTTPServer 80 &
               EOF
 }

 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"
   vpc_zone_identifier  = [aws_subnet.public_subnet_2a.id, aws_subnet.public_subnet_2b.id]
 }
```
🛠️ This Terraform code creates two AWS resources: an Auto Scaling Group and a launch configuration.
- aws_launch_configuration: This resource creates a launch configuration for EC2 instances that we are going to deploy as part of our Auto Scaling Group.
  - image_id: The EC2 image ID to launch. 🖼️
  - instance_type: The size of instance to launch. 📏
  - security_groups: A list of associated security group IDs. 🛡️
  - user_data: The script to be executed when an instance is launched, which starts a simple web server. 🌐
- aws_autoscaling_group: Provides an Auto Scaling Group resource.
  - max_size: Maximum size of the Auto Scaling Group. 🚀
  - min_size: Minimum size of the Auto Scaling Group. 📉
  - desired_capacity: Number of Amazon EC2 instances that should be running in the group. 📈

🔧 This Terraform script creates an AWS VPC with two public subnets in different availability zones, an internet gateway, a public route table, and route table associations. It also creates an AWS security group that allows SSH and HTTP traffic, a launch configuration that uses user data to start a Python HTTP server on port 80, and an Auto Scaling Group with a minimum of 1, maximum of 3, and desired capacity of 2 instances, spread across the two subnets.

Run terraform init to initialize the Terraform project. ⚙️
Run terraform plan to see the execution plan. 📝
Run terraform apply to create the Auto Scaling Group. 🚀
```
 terraform apply
```

🔍 Below, two new EC2 instances created as desired capacity set to 2:

✅ Launch configuration successfully created:

📊 Auto Scaling Group is created with group details:

🚀 Two instances are running in the Auto Scaling Group:

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. 🖥️❌