Terminate instance and decrement capacity in ASG

terminateAndScaleDownAsg.sh

#!/usr/bin/env bash

if [ -n "$1" ]; then
  minutesBeforeTerminate=$1
else
  minutesBeforeTerminate=1440
fi

decimal=0
secondsUptime=`awk {'print $1'}  /proc/uptime`
minutesUptime=`echo "scale=$decimal; $secondsUptime / 60" | bc`
loggedInUsers=`users | wc -l`

function scaleDown
{
  instanceId=`curl -s -l http://169.254.169.254/latest/meta-data/instance-id`
  az=`curl -s -l http://169.254.169.254/latest/meta-data/placement/availability-zone`
  region=${az%?}
  aws autoscaling terminate-instance-in-auto-scaling-group --instance-id $instanceId --should-decrement-desired-capacity --region $region
}

if [ $loggedInUsers -eq 0 ] && [ $minutesUptime -ge $minutesBeforeTerminate ]; then
  echo "Number of users logged in:" $loggedInUsers
  echo "Uptime in minutes:" $minutesUptime
  echo "Self-terminating instance in ASG and decrementing capacity"
  scaleDown
else
  echo "Number of users logged in:" $loggedInUsers
  echo "Uptime in minutes:" $minutesUptime
fi