AWS Create EMR using boto3 Autoscaling not working properly

Question

I am auto scaling emr using boto3 and then autoscaling it using EMR_AutoScaling_DefaultRole. Autoscaling not working properly:

Initially it gives a warning as

The policy is pending attachment.

and at last failing giving error as

The Auto Scaling policy for instance group ig-XXXXXXXXXXXX in Amazon EMR cluster j-XXXXXXXXXXXX (test_emr...) could not attach and failed at 2018-12-19 10:03 UTC.

What can I do to assign the Autoscaling role?

Answer 1

In addition to answer by @Harsh Bafna. You also need to set Trust Relationship policy for EMR_AutoScaling_DefaultRole role.

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Principal": {
        "Service": [
          "application-autoscaling.amazonaws.com",
          "elasticmapreduce.amazonaws.com"
        ]
      },
      "Action": "sts:AssumeRole"
    }
  ]
}