config

cf_auth_key=
cf_email=
zone_id=
zone_name=
record_id=
fqdn=
ttl=1800
tmpfile=/tmp/latest-ip.txt

get_zone_ids.sh

cf_auth_key=
cf_email=

curl -X GET "https://api.cloudflare.com/client/v4/zones" \
    -H "X-Auth-Email: $cf_email" \
    -H "X-Auth-Key: $cf_auth_key" \
    -H "Content-Type: application/json" | jq .

zone_id=

curl -X GET "https://api.cloudflare.com/client/v4/zones/$zone_id/dns_records" \
    -H "X-Auth-Email: $cf_email" \
    -H "X-Auth-Key: $cf_auth_key" \
    -H "Content-Type: application/json" | jq .

record_id=

update-cloudflare

#!/bin/sh
. /etc/update-cloudflare/config

WAN_IP=`curl http://icanhazip.com/ 2> /dev/null`
OLD_WAN_IP=`cat $tmpfile`

if [ "$WAN_IP" = "$OLD_WAN_IP" ]
then
    touch $tmpfile
else
    curl -X PATCH "https://api.cloudflare.com/client/v4/zones/$zone_id/dns_records/$record_id" \
    -H "Content-Type:application/json" \
    -H "X-Auth-Key:$cf_auth_key" \
    -H "X-Auth-Email:$cf_email" \
    --data '{
        "id":"'"$record_id"'",
        "type":"A",
        "name":"'"$fqdn"'",
        "content":"'"$WAN_IP"'",
        "ttl":"'"$ttl"'",
        "zone_id":"'"$zone_id"'",
        "zone_name":"'"$zone_name"'",
        "data":{}
    }'
    echo $WAN_IP > $tmpfile
fi