AWSからACMの更新メールが来ないときあるので、念のため作ってみた
速攻作ったので、クレーム一切受け付けません

jq不使用
複数アカウント対応

#!/bin/bash

now=`date "+%s"`
_lockfile_dir=/***/***/.acm-tmp-lock
_lockfile=${_lockfile_dir}/acm_check.lock

[ -d ${_lockfile_dir} ] || mkdir ${_lockfile_dir}

if [ -f ${_lockfile} ]; then
    echo "LOCKED"
    exit 1
fi

#Create LockFile
touch ${_lockfile}

_conf=/***/***/conf/
_date=`date`

for _confgile in `ls -1 ${_conf}|grep knife.rb`
do
    _title=`echo ${_confgile} | sed 's/\-knife.rb//g'`
    _region=`grep region ${_conf}${_confgile} | cut -d '=' -f 2 | cut -d '"' -f 2`
    chanel_name='#chanel-name'

    all_region=(us-east-2 us-east-1 us-west-1 us-west-2 ap-south-1 ap-northeast-2 ap-southeast-1 ap-southeast-2 ap-northeast-1 ca-central-1 eu-central-1 eu-west-1 eu-west-2 sa-east-1)
    for region_all in ${all_region[@]}
    do
      for acmid in `aws --profile ${_title} --region ${region_all} acm list-certificates --output text | awk -F " " '{print $2}'`
      do

        certificate_name=`aws --profile ${_title} --region ${region_all} acm describe-certificate --certificate-arn ${acmid} --query Certificate.[DomainName] --output text`
        certificate_use=`aws --profile ${_title} --region ${region_all} acm describe-certificate --certificate-arn ${acmid} --query Certificate.[InUseBy] --output text`
        certificate_unix_time=`aws --profile ${_title} --region ${region_all} acm describe-certificate --certificate-arn ${acmid} --query Certificate.[NotAfter] --output text | awk -F "." '{print $1}'`
        if [ "${certificate_unix_time}" != "None" ]; then
         jst_time=`date -d @$certificate_unix_time`
         rema_check=`expr $certificate_unix_time - $now`
         rema_time=`expr $rema_check / 86400 + 1`
        fi

         if [ $rema_time -lt 40 ] && [ -n "${certificate_use}" ]; then
           curl -X POST --data-urlencode "payload={\"channel\": \"$chanel_name\", \"username\": \"ACM-Alert\", \"text\": \" Warning remaining $rema_time day $certificate_name $region_all\", \"icon_emoji\": \":warning:\"}" https://hooks.slack.com/
         elif [ $rema_time -lt 40 ]; then
           curl -X POST --data-urlencode "payload={\"channel\": \"$chanel_name\", \"username\": \"ACM-Alert\", \"text\": \" Info remaining $rema_time day $certificate_name but Not Use ACM $region_all\", \"icon_emoji\": \":warning:\"}" https://hooks.slack.com/
         else
          echo "[Remaining] ${rema_time}day" #ファイルに吐いてもいいと思う　なんでもいい
         fi

      done
   done
done

rm -f ${_lockfile}

動かなくても何も言わないでね！！
そのうちDocker化してみる