#!/bin/bash
#
# Note that this requires the really cool command-line tool 'jq'
#

if [ -z "$1" ]; then
    echo "as_kill_instances [group]"
    exit -1
fi

instances=$(aws autoscaling describe-auto-scaling-groups --auto-scaling-group-names $1 | jq -r .AutoScalingGroups[0].Instances[].InstanceId )

for instance in $instances ; do
    aws autoscaling terminate-instance-in-auto-scaling-group \
        --instance-id $instance \
        --no-should-decrement-desired-capacity
done