Introduction

• In real life, the load on your website and application can change.
• In the cloud, you can create & get rid of servers very quickly.
• The goal of an ASG is to:
  • Scale Out (add EC2 Instances) to match an increasing load
  • Scale In (remove EC2 Instance) to match a decreasing load.
  • Ensure we have a minimum & maximum number of machine running.
  • Automatically register new instances to a load balancer
  • Automatically Replaces unhealthy instances!!
• Cost Saving: Only run at an optimal capacity (principal of the cloud)

Scaling Strategies

There are 2 types of strategies which we can implement. Manual & Dynamic Scaling (using ASGs). - Manual Scaling : Update the size of ASG Manually.

Strategy Name	Explaination
Simple/Step Scaling (AKA Dynamic Scaling)	When CloudWatch Alarm is triggered (example CPU > 70%), then add 2 EC2 Instances.
	When CloudWatch Alarm is triggered (example CPU < 30%), then remove 1 EC2 Instances.
Target Tracking Scaling	”I want the AVERAGE ASG CPU to stay at 40%” (we use CloudWatch’s parameters to make decision by tracking a specific parameters of the target. )
Scheduled Scaling	Anticipate scaling based on known usage patterns.
Predictive Scaling	Using ML to predict future traffic ahead of time.
	Automatically provision the right amount of EC2 instances in advance.