Implementing Auto Scaling on AWS: A Step-by-Step Guide

Rukee Ojigbo — Sun, 18 Jun 2023 20:17:47 +0000

Introduction:

In this article, you will learn the process of implementing auto scaling on AWS, which allows you to automatically adjust the number of instances in your application based on demand. You will be guided through each step, accompanied by explanations and helpful screenshots, making it easier for you to follow along. Additionally, we will cover the essential concepts of launch templates and load balancing, ensuring a comprehensive understanding of the topic. Join us as you delve into the world of auto scaling and empower your AWS infrastructure for optimal performance.

Prerequisite:

Before proceeding with this tutorial, it is assumed that you have the following prerequisites in place:

AWS Account: You should have an active AWS account that allows you to access and manage AWS services.
Basic Understanding of EC2 Instances: It is recommended to have a basic understanding of Amazon EC2 (Elastic Compute Cloud) instances, including how to launch and manage them.
Familiarity with Availability Zones: It is beneficial to have knowledge about AWS Availability Zones, which are distinct physical locations within an AWS Region designed to provide high availability and fault tolerance.

Alright let's jump in...

Step 1: Sign into the AWS console
To begin, sign into the AWS console using your credentials.

Step 2: Search and select EC2
In the search bar, type "EC2" and select it from the dropdown menu.

Step 3: Create an Auto Scaling Group
Scroll down on the left-hand side and click on "Create Auto Scaling Group".

Step 4: Configure Auto Scaling Group
Provide a name for the Auto Scaling Group and create a launch template. In the diagram below, we have chosen the name 'demo-autoscaling-group'.

What is a launch template?
Think of a launch template as a blueprint for creating EC2 instances. Instead of manually specifying configurations such as AMIs, instance types, and security groups each time you create an instance, a launch template allows you to define these configurations in advance. This saves you time and provides flexibility, as you can have multiple versions of the template to suit different needs. With a launch template, you can easily create instances with pre-defined configurations, eliminating the need for repetitive manual configuration.

Step 5: Create a Launch Template
Click on "Create Launch Template" to open a new tab. Enter a template name and description.

Step 6: Customize the Launch Template
Select an AMI image for your EC2 instance and choose an instance type. Create a security group to control inbound and outbound traffic.

In the provided image, I have personally selected the Ubuntu AMI

In the image above, I have selected the t2.micro instance type, which is suitable for this demo and falls under the free tier usage.

In the image above, we click on "Create a key pair". A key pair is essential as it enables SSH access into our instance.

Enter a name for your key pair, and click "Create". This action will prompt the download of a .pem file. It is recommended to download the file to a directory that you can easily access.

Next, scroll down to network settings:

We have opted to create a new security group, which acts as a firewall, controlling the network access to our server/instance.

In the image above, we have provided a name for our security group, entered a description, and selected the VPC where the server/instance will be created.

Next, we add the rules for our security group

In our security group configuration:

Rule 1 allows SSH access from our specific IP address, using the default port 22.

Rule 2 permits internet access over the HTTP protocol (port 80) from any source.

Rule 3 does the same as Rule 2 but for HTTPS (port 443).

Now, let's proceed to the next steps:

Scroll down to the "Advanced details" section.

Refer to the image (Image 1) for visual guidance.

Click on the dropdown arrow to expand and reveal more options.

In the expanded section, locate the "User data" field.

Copy and paste the following script into the "User data" field

#!/bin/bash
# Update package repository
apt-get update

# Install Apache web server
apt-get install -y apache2

# Retrieve instance ID
INSTANCE_ID=$(curl -s http://169.254.169.254/latest/meta-data/instance-id)

# Create the HTML file with custom content
cat <<EOF > /var/www/html/index.html
<!DOCTYPE html>
<html>
<head>
  <title>Welcome to my website</title>
</head>
<body>
  <h1>Hello, world!</h1>
  <p>This is my awesome demo launch template website</p>
  <p>Instance ID: $INSTANCE_ID</p>
</body>
</html>
EOF

# Start the Apache service
service apache2 start

Note: The script provided in the user data section is optional and serves as an example. It is designed to configure the launched instances from your template with a basic Apache web server and a custom HTML page. Feel free to modify this script to meet your specific requirements. You can install additional software, configure different settings, or even add your own custom content. The purpose of including this script is to demonstrate the capabilities of user data in customizing instances launched from your template.

Click the "Create launch template" button on the right side. Upon successful creation, you will see a confirmation screen with relevant details.

Congratulations on creating the launch template! Now, let's continue creating the auto-scaling group using the recently created launch template.

Step 7: Return to Auto Scaling Group Creation
Go back to the previous tab and click the refresh button. Select the launch template you just created. Then click next.

Step 8: Configure Instance Launch Options
Choose the VPC in which you want to launch your resources. Select the desired availability zones.

In the image above, we have selected the default VPC. Normally, you would choose the VPC where you are launching your resources. Additionally, we have selected the availability zones US-east-1a and US-east-1b. Our instance will span across these zones, enhancing redundancy.