I have a EKS cluster with min 3 and max 6 nodes, Created auto scaling group for this setup, How can i implement auto scale of nodes when spike up/down on Memory usage since there is no such metric in Auto scaling group like cpu. Can somebody please suggest me clear steps i am new to this setup .
You need to deploy cluster autoscaler which will increase or decreased number of nodes for you.
See the official docs.
Out of the box ASG does not support scaling based on the memory utilization. You`ll have to use custom metric to do that.
Here is way how to do that.
Have you considered using CloudWatch alarms to monitor your nodes? The scripts can collect memory parameters that can be used later.
See here how to set it up.