ASG

Describe about What is ASG ?

ASG or Auto scaling group it is a service of AWS that use to scale out/in for EC2 instance. ASG are free but you need to pay for the new instances that running. You need to specify

• (1) Minimum capacity (Numbers of minimum instance)

• (2) Desired Capacity (Numbers of current running instance)

• (3) Maximum capacity (Numbers of maximum instance)

Scaling Policies

(1) Dynamic Scaling

• Target Tracking Scaling = It is most simple way you can set up in ASG byyourself example: I want the average ASG CPU to stay around 40 % if not it will scale out.

• Simple/Step Scaling = It use AWS Cloud watch alarm to trigger ASG. example: When CPU > 70% then add 2 units.

• Scheduled Actions = It is a pattern that we can customize for trigger. example: increase the min capacity to 10 at 5 pm on Fridays.

(2) Predictive Scaling

It will forecast load and you can set the rule to scale it.

After a scaling activity happen, ASG will cooldown (default 300 sec). During this time ASG will not launch or terminate additional instance. Advice: Use AMI to reduce configuration time in order to be serving request fasters and reduce the cooldown period.