🚀Day 05: Setting Up Auto Scaling for Your EC2 Instances in AWS

As your application usage grows, you need a way to handle sudden traffic spikes or drop resources when they're no longer needed. That’s where AWS Auto Scaling steps in — automatically adjusting the number of EC2 instances to match the demand. In this post, we’ll walk through how to set up Auto Scaling for EC2 instances step-by-step.

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✅ What is Auto Scaling?

Auto Scaling is a feature in AWS that automatically launches or terminates EC2 instances based on:

• CPU utilization

• Network usage

• Custom CloudWatch metrics

• Scheduled times

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Prerequisites

Before setting up Auto Scaling, you should have:

1. An EC2 instance running in a public subnet.

2. A Launch Template or Launch Configuration.

3. A Load Balancer (optional but recommended).

4. IAM permissions to create Auto Scaling groups and policies.

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🛠️ Step-by-Step Guide

1️⃣ Create a Launch Template

A Launch Template defines the AMI, instance type, key pair, security groups, and other configurations.

• Go to EC2 Console → Launch Templates

• Click Create launch template

• Enter name and version description

• Choose AMI and instance type (e.g., Amazon Linux 2, t2.micro)

• Add storage, security group, and key pair

• Click Create launch template

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2️⃣ Create an Auto Scaling Group

• Go to EC2 Console → Auto Scaling Groups

• Click Create Auto Scaling group

• Select the Launch Template

• Name your Auto Scaling group

• Choose the VPC and Availability Zones

• (Optional) Attach a Load Balancer (like an Application Load Balancer)

• Set Group size (e.g., min=1, desired=2, max=3)

• Enable Health checks (EC2 and/or ELB)

• Click Next and configure scaling policies

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3️⃣ Set Scaling Policies

• Select Target tracking scaling policy

• Choose metric (e.g., Average CPU Utilization)

• Set target value (e.g., 50%)

• AWS will automatically scale up/down to maintain this threshold

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4️⃣ Review and Create

• Review all configurations

• Click Create Auto Scaling group

Your Auto Scaling group is now live!

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🔍 Monitoring Auto Scaling

You can monitor instance activity from:

• EC2 → Auto Scaling Groups (activity tab)

• CloudWatch Dashboards

• SNS notifications (optional)

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🧠 Final Thoughts

Auto Scaling helps you build a resilient, scalable, and cost-effective architecture.