A script to detect all the instances in an autoscaling group and assign one as the master.

master_and_slave

#!/usr/bin/env python
import sys
import boto3

def main(argv):
    autoscaling = boto3.client('autoscaling')
    auto_scaling_groups = autoscaling.describe_auto_scaling_groups()['AutoScalingGroups']
    for asg in auto_scaling_groups:
      break

if __name__ == "__main__":
    main(sys.argv)