nlb-ip-check.sh

#!/bin/bash

warning_list=""
RED="\033[0;31m"
NC="\033[0m"


for target_group in $(aws elbv2 describe-target-groups --query "TargetGroups[?starts_with(TargetGroupName, 'serverless-')].TargetGroupArn" --output text)
  do
    echo "---------------------------------------"
    dns=$(aws elbv2 describe-tags --resource-arns "$target_group" --query "TagDescriptions[*].Tags[?Key=='dns'].Value" --output text)
    echo "Backend DNS: $dns"

    new_ip=""
    for ip in $(dig +short "$dns" | sort)
      do
        if [[ "$ip" == "192."* ]]
          then
            if [ "$new_ip" = "" ]
              then
                new_ip=$ip
              else
                new_ip="$new_ip $ip"
            fi
        fi
      done
    echo "New IP: $new_ip"

    old_ip=$(aws elbv2 describe-tags --resource-arns "$target_group" --query "TagDescriptions[*].Tags[?Key=='ip'].Value" --output text)
    echo "Old IP: $old_ip"

    if [ "$new_ip" != "$old_ip" ]
      then
        echo -e "${RED}IP addresses have changed!${NC}"
        if [ "$warning_list" = "" ]
          then
            warning_list=$dns
          else
            warning_list="$warning_list, $dns"
        fi
      else
        echo "IP addresses are still the same"
    fi
  done

echo "-----------------Summary------------------"
if [ "$warning_list" != "" ]
  then
    echo -e "${RED}${warning_list} IP addresses have changed${NC}"
    echo "::set-output name=re_deploy::yes"
  else
    echo "All good!"
    echo "::set-output name=re_deploy::no"
fi