Auto-scaling in AWS

What is Auto Scaling?

AWS Auto Scaling automatically adjusts the number of compute resources (like EC2 instances) based on demand, ensuring applications maintain performance while controlling costs.

Key Components

• Launch Template/Configuration — defines the instance type, AMI, and settings for new instances.
• Auto Scaling Group (ASG) — manages a collection of EC2 instances, scaling them in or out.
• Scaling Policies — rules that determine when to add or remove instances, based on metrics like CPU utilization.

Types of Scaling Policies

• Target tracking scaling — maintains a target metric value, e.g. 50% average CPU.
• Step scaling — adjusts capacity based on the size of the alarm breach.
• Scheduled scaling — scales at predictable times, e.g. before a known traffic spike.

Auto Scaling works closely with Elastic Load Balancing to distribute traffic evenly across the running instances.