Cloudflare as Dynamic DNS (revised)

lwp-cloudflare-dyndns.sh

#!/bin/bash
# Cloudflare as Dynamic DNS
# From: https://letswp.io/cloudflare-as-dynamic-dns-raspberry-pi/
# Based on: https://gist.github.com/benkulbertis/fff10759c2391b6618dd/
# Original non-RPi article: https://phillymesh.net/2016/02/23/setting-up-dynamic-dns-for-your-registered-domain-through-cloudflare/

# Fixed and documented version by Christian Gambardella (https://gambo.io)
# 1. Create a cloudflare account
# 2. Create a zone and a record with any ip address.
#    It will be updated by the script.
#    Just put 127.0.0.1 or so.
# 3. Create a token with those permissions:
#    zone / zone / read
#    zone / DNS / edit
#    limit to all zones from your account or all zones. specific zones are not enough.
# 4. Update this script to include your zone name, record name and auth token.
# 5. Put it somewhere
# 6. Install a cronjob using `crontab -e`
# 7. Add line to update every 10 minutes: `*/10 * * * * /home/pi/cron/lwp-cloudflare-dyndns.sh`

# Update these with real values
auth_token="<auth-token-here>"
zone_name="domain.com"
record_name="home.domain.com"

# Don't touch these
ip=$(curl -s http://ipv4.icanhazip.com)
ip_file="ip.txt"
id_file="cloudflare.ids"
log_file="cloudflare.log"

# Keep files in the same folder when run from cron
current="$(pwd)"
cd "$(dirname "$(readlink -f "$0")")"

log() {
    if [ "$1" ]; then
        echo -e "[$(date)] - $1" >> $log_file
    fi
}

log "Check Initiated"

if [ -f $ip_file ]; then
    old_ip=$(cat $ip_file)
    if [ $ip == $old_ip ]; then
        log "IP has not changed."
        exit 0
    fi
fi

if [ -f $id_file ] && [ $(wc -l $id_file | cut -d " " -f 1) == 2 ]; then
    zone_identifier=$(head -1 $id_file)
    record_identifier=$(tail -1 $id_file)
else
    zone_identifier=$( curl -s -X GET "https://api.cloudflare.com/client/v4/zones?name=$zone_name" -H "Authorization: Bearer $auth_token" -H "Content-Type: application/json" | grep -Po '"id": *\K"[^"]*"' | head -1 | tr -d \" )
    record_identifier=$( curl -s -X GET "https://api.cloudflare.com/client/v4/zones/$zone_identifier/dns_records?name=$record_name" -H "Authorization: Bearer $auth_token" -H "Content-Type: application/json" | grep -Po '(?<="id":")[^"]*' )
    echo "$zone_identifier" > $id_file
    echo "$record_identifier" >> $id_file
fi

echo "record: $record_identifier"
echo "zone: $zone_identifier"

update=$(curl -s -X PUT "https://api.cloudflare.com/client/v4/zones/$zone_identifier/dns_records/$record_identifier" -H "Authorization: Bearer $auth_token" -H "Content-Type: application/json" --data "{\"id\":\"$zone_identifier\",\"type\":\"A\",\"name\":\"$record_name\",\"content\":\"$ip\"}")

if [[ $update == *"\"success\":false"* ]]; then
    message="API UPDATE FAILED. DUMPING RESULTS:\n$update"
    log "$message"
    echo -e "$message"
    exit 1
else
    message="IP changed to: $ip"
    echo "$ip" > $ip_file
    log "$message"
    echo "$message"
fi