AUTO-SCALING

Auto Scaling is one of those game-changing AWS features that makes your infrastructure smart, resilient, and cost-efficient. If you've ever wondered how websites handle sudden traffic surges without crashing or burning money, this is where Auto Scaling shines.

In this guide, I will walk you through the basics of AWS Auto Scaling, how to set it up, and what pitfalls to watch out for — especially if you’re just starting your cloud journey.

What is AWS Auto Scaling?

AWS Auto Scaling automatically adjusts the number of EC2 instances in your application based on demand. Whether your traffic spikes or drops, Auto Scaling ensures your app stays available and you only pay for what you use.

✨** Why Use Auto Scaling?**

• High availability during peak loads
• Reduced costs during low traffic
• Improved fault tolerance
• Hands-free instance management

🧱 Core Components of Auto Scaling

Here’s what makes it all work:

1. Launch Template – Defines the configuration for launching EC2 instances (AMI, instance type, etc).

2. Auto Scaling Group (ASG) – Manages and maintains the number of instances. It ensures that a defined number of instances are running based on user-defined minimum, maximum, and desired capacity.

3. Scaling Policies – Define how the group should scale (Target Tracking, Step Scaling, or Scheduled).

4. CloudWatch Alarms – Monitor CPU usage or other metrics to trigger scaling.

Practical Exapmple:

TechNova experiences inconsistent traffic. During working hours, there is heavy traffic. After hours, the load reduces. Your task is to configure an Auto Scaling Group to scale based on CPU usage.

🛠️ Setting Up Auto Scaling (Step-by-Step)

1. Launch two EC2 on different Availability zone (AZ)

• Selected your preferred AMI
• Instance type
• Key pair -Security group

2. Create Target Group

Go to Load Balancing Option and select Target group.Then click on create target group.

Select Instance option and name your Target Group

You can leave other options on default and click next then select the two instances, then click on create target group.

3. Create Load Balance

Go to Load Balance option and click on it, then click on create load balance.

Select Application Load balancer and click on Create

Select two different Availability Zones in-line with your instance. (Example: Mine is us-east-1c & us-east-1d)

Under Security **
**Select at least one Security group

Under Listeners and routing.
Select your target group
Then click on "Add Listener"

After clicking on the Add Listener, select the Target group again

*Then click on Create Load Balancer *

4. Launch Template
Search for Launch Template and Select it accordgingly.

*Click on Create Launch Template *

*Name your template: *

Click on "Browse more AMIs" to select your AMI.
Then, select your instance type

Select your Key pair and also select one security group

Click on Advanced Settings and scroll down

*Insert this command on this User-data: *

yum update -y
yum install httpd -y
systemctl start httpd
systemctl enable httpd
echo "Welcome to Web Server - $(hostname)" > /var/www/html/index.html

*Then, click on Create Launch Template. *

5. Create Auto-Scaling

Select Auto Scaling and click on Create Auto Scaling

Name your Auto scaling group and Select the template you created.
Then click on next.

Select two different Availability zone, then click on next.

Select "Attach to an existing load balancer" and then select the target group you created earlier

Select "Turn on Elastic Load Balance Health Checks" and click on next.

For this exercise we are using 3 as maximum desired capacity and 1 as the minimum capacity. So select it accordingly.

Also select Target Scaling Policy and click on next to create the Auto-Scaling

DONE

*Now refresh your instance. *

You will notice that new instances are launched, some get terminated as demand decreases, and others are started again as needed — all automatically managed by Auto Scaling.

Auto Scaling automatically creates new EC2 instances when your current instance(s) can't handle the load for example, when CPU usage goes above a defined threshold like 60%.

LESSON I LEARNED

• Set the right cooldown period to avoid frequent unnecessary scaling
• Choose the correct target metric for your workload
• Monitoring with CloudWatch is critical for visibility

*CONCLUSION: *

Auto Scaling saved TechNova both performance issues and unnecessary costs. By simply leveraging AWS-native tools like ASG, Launch Templates, and CloudWatch, we were able to build a resilient, adaptive infrastructure that scales as needed.

Want to try it for your own projects? Start small, experiment, and let the cloud do the heavy lifting. ☁️💪