Bash script that checks for IP change and updates Route53

update_on_ip_change.sh

#!/bin/bash
# Usage: Launch in the background and pass RECORD_SET_NAME (e.g. sub.example.com.) 
# as a first argument for the Route53 record. Log file can be found at /var/tmp/r53-record.log

NOTIFY_DIR=/var/tmp
LOG_FILE=${NOTIFY_DIR}/r53-record.log
CURR_IP_FILE=${NOTIFY_DIR}/ip.out
TMP_IP_FILE=${NOTIFY_DIR}/ip.tmp
IP_LKP_URL=https://ifconfig.me/ip
RECORD_SET_FILE=${NOTIFY_DIR}/r53-record-set.json
RECORD_SET_NAME=${1}
RECORD_SET_TTL=300

function create_record_json {
	cat << EOF > ${RECORD_SET_FILE}
{
 "Changes": [
  {
   "Action": "UPSERT",
   "ResourceRecordSet": {
    "Name": "${RECORD_SET_NAME}",
    "Type": "A",
    "TTL": ${RECORD_SET_TTL},
    "ResourceRecords": [
     {
      "Value": "${1}"
     }
    ]
   }
  }
 ]
}
EOF
}

function update_route53_record {
	local new_ip=$(cat ${CURR_IP_FILE})
	create_record_json "${new_ip}"
	local resp=$(aws route53 change-resource-record-sets --hosted-zone-id ${HOSTED_ZONE_ID} --change-batch file://${RECORD_SET_FILE})
	echo "Updated route53 record:" >> ${LOG_FILE}
	echo "${resp}" >> ${LOG_FILE}
}

create_record_json "127.0.0.1"
curl -sf $IP_LKP_URL > $CURR_IP_FILE

while [[ true ]]; do
	printf $(curl -sf $IP_LKP_URL) > $TMP_IP_FILE
	IP_DIFF=$(diff -w $TMP_IP_FILE $CURR_IP_FILE)
	if [[ "$IP_DIFF" != "" ]]; then
		echo "We have a new IP: $(cat $TMP_IP_FILE)" >> ${LOG_FILE}
		cat $TMP_IP_FILE > $CURR_IP_FILE
		update_route53_record
	fi
	sleep 300s
done

This script now has a home at https://github.com/jeffrade/proxy-server