Does auto scale-in policy remove instances below desired capacity ?

Question

I am facing a problem related to 'Desired Capacity' and 'Minimum Capacity'.    
  
My ASG has desired capacity as 2, minimum capacity as 1 and maximum capacity as 6. There is a scale-in policy (and CloudWatch alarm) to remove 1 instance when 'CPU Utilization' is below 20%.  
  
The alarm is getting triggered and I can see that in both cloudwatch dashboard plus EC2 dashboard against the instance.  
  
However the problem is the auto-scale in policy is not getting trigged and the instance is not terminated. In EC2 dashboard the status becomes 'No data' and in CloudWatch dashboard the state becomes 'Insufficient Data'.  
  
Can you please let me know why 1 instance is not getting terminated ? Is it because my desired capacity is 2 ??  
  
My minimum capacity is 1 so isn't it that after alarm is triggered 1 instance will be terminated ?

Answer

thank you

Answer

Have you looked at the autoscale group in the EC2 console?  check the activity history tab...e.g.  
https://console.aws.amazon.com/ec2autoscaling/home?region=us-east-1#/details  
  
..if your alarm is properly hooked up to the ASG action, you should see something there that would help.  
  
Also on the details tab for the ASG, be sure there are no:  
Suspended processes

Does auto scale-in policy remove instances below desired capacity ?

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