aws-route53-tidy.sh

#!/usr/bin/bash
#
# If an EC2 Instance tag Name matches a record in DNS (Route53) and the EC2 Instance is removed without Tidying Route53 Zone,
# This script will find the "orphaned" Zone records, and remove them.
#
rm -f /tmp/delete-r53.json
ZONEID=$(aws route53 list-hosted-zones-by-name |jq -r '.HostedZones[]|select (.Config.PrivateZone)|select (.Name|contains("example.com"))|.Id')
#
# Get a list of all DNS Records which don't have a running instance
#
RECORDSTOREMOVE=$(comm -23 <(aws route53 list-resource-record-sets --hosted-zone-id $ZONEID|jq -r '.ResourceRecordSets[]|select (.Name|startswith("my-app"))|(.Name| split("."))[0]'|sort) <(aws ec2 describe-instances --filters "Name=tag:Name,Values=my-app*"|jq -r '.Reservations[].Instances[].Tags[]|select (.Key=="Name")|(.Value|split(" "))[0]'|sort)|jq --slurp --raw-input 'split("\n")[:-1]')
#
# Generate JSON String of changes to delete discovered Records
#
aws route53 list-resource-record-sets --hosted-zone-id $ZONEID|jq --argjson toremove "$RECORDSTOREMOVE"  '[.ResourceRecordSets[] |select ([.Name|split(".")[0]]|inside($toremove))|{Action: "DELETE", ResourceRecordSet: {Name: .Name, ResourceRecords: .ResourceRecords,Type: .Type, TTL: .TTL }}]|{Comment: "Bye Bye Superfluous Records",Changes: .}' > /tmp/delete-r53.json
#
# Provide basic feedback
#
[ $(grep Name /tmp/delete-r53.json|wc -l) -eq 0 ] && echo "No superfluous records" && exit
grep Name /tmp/delete-r53.json
grep Name /tmp/delete-r53.json|wc -l

read -n 1 -s -r -p "Looking good ? - press ctrl C if not!!"
#
# Make it happen!
#
aws route53 change-resource-record-sets --hosted-zone-id $ZONEID --change-batch file:///tmp/delete-r53.json