086 Auto Scaling Group

Goal:

• Scale out (add EC2 instances)
• Scale in (remove EC2 instances)
• Min/Max EC2 instances
• Automatically register new instances to a load balancer
• Re-create an EC2 instance

ASG is free

ASG in AWS

ASG works with EC2

• Minimum capacity
• Desired capacity
• Maximmum capacity

ASG Attributes

A launch template

• AMI, instance type
• EC2 user data
• EBS
• Security groups
• SSH key pair
• IAM roles
• network, subnets
• load balancer

Min/Max size

Initial capacity

Scaling policy

CloudWatch Alarms

Alarm monitors a metric over ASG instances

• average CPU, …

Based on the alarm, we can create

• Scale-out policy
• Scale-in policy