I would lik eto know if it can increase the CPU or memory based on user defined threshhold on a single instance?
No, it does not. Not at-least at the time of writing this. They might add that feature in the offing.
In current situation, the only way to ad more CPU/MEM to an instance is to shut it down and then change instance type
. This option is available in AWS Console and I am not sure of APIs.
While changing the instance type, you can choose a bigger type of instance
which will eventually get you more CPU/MEM.
There is no way to add more CPU/MEM to a running instance at the moment. In fact, there is no way to add CPU/MEM to a current instance without changing its instance type.
Autscaling does not do this either.