CODEWITHSUNDEEP
amazon-web-servicesautoscaling
MWM
MWM

Reputation: 37

AWS Auto Scaling - with 2 fixed instances

I have a situation where I have kept 2 fixed instances behind an ELB and setup an auto scaling with minimum instances as 0. This is because these 2 instances have some additional applications besides the core website which is being served by the AMI being in setup auto scaling launch configuration - the reason being - in most cases these 2 instances can manage the loads as well as help with additional applications which I do not want in other new instances during peak hours (which auto scaling will load - I guess).

My questions are -

1) Is this setup OK? the auto scaling is configured with the same ELB - however would it scale out when current 2 instances (not part of auto scaling) will reach the event level (>70% CPU)?

2) These 2 instances are termination protection enabled. Would auto scaling not touch them during scale in as they were not created by auto scaling?

Upvotes: 0

Views: 323

Answers (2)

Henry
Henry

Reputation: 1686

I'm not sure re: termination protection/setting up when to scale down, but best practise would indicate setting up autoscaling minimum size of 2, and having your two instances as part of that ASG.

Upvotes: 0

Matt Houser
Matt Houser

Reputation: 36053

An ELB can have any number of EC2 instances behind it. Those instances can be controlled by Auto Scaling or by your own creating/termination. Elastic Load Balancing won't care which are which. There is no "proper" mix.

Auto Scaling will not affect your 2 individual EC2 instances, termination protection or not. Auto Scaling will only terminate EC2 instances that it created itself.

Also, Auto Scaling will not take input from your 2 EC2 instances automatically. You can probably hook metrics from them to scale your Auto Scaling group up/down, but it won't happen automatically just because they are behind the same ELB.

Upvotes: 1

Related Questions