Update Cloudflare A record when your IP changes

dynhost-cf.sh

#!/bin/bash
# Updates Cloudflare dns record
# when your home IP changes

# Put in in cron with desired frequency
# but don't abuse WTF service (they throttle anyway)

set -e

API_TOKEN=YOUR_API_TOKEN_HERE
ZONE=$1
DNS_ID=$2
DNS_NAME=$3

if [[ $# -lt 3 ]]; then
  echo "Not enough arguments"
  exit 1
fi

getip() {
	IP=`curl -sL https://wtfismyip.com/text`
    OLDIP=`cat ./${DNS_NAME}-old.ip`
}

logger() {
        echo `date +%Y:%H:%M:%S` $1 >> ./${DNS_NAME}.log
}

getip

if [ "$IP" ]; then
    if [ "$OLDIP" != "$IP" ]; then
       	logger "Old IP: $OLDIP => New IP: $IP"

        curl --silent -X PUT "https://api.cloudflare.com/client/v4/zones/$ZONE/dns_records/$DNS_ID" \
            -H "Authorization: Bearer $API_TOKEN" \
            -H "Content-Type: application/json" \
            --data "{\"type\":\"A\",\"name\":\"${DNS_NAME}\",\"content\":\"${IP}\",\"proxied\":true}" \
            && echo -n "$IP" > ./${DNS_NAME}-old.ip && logger "IP updated to $IP" \
            || logger "Couldn't update IP"
    fi
else
    logger "Could not get IP from wtf"
fi