cf_dyndns.py

import requests

API_KEY="<YOUR-API-KEY>"
BASE_URL="https://api.cloudflare.com/client/v4/"
EMAIL="<YOUR-EMAIL>"
DOMAIN="<YOUR-DOMAIN>"
SUBDOMAIN="<YOUR-SUBDOMAIN>"

def get_ip_address():
    r = requests.get("https://api.ipify.org?format=json")
    return r.json()["ip"]

def get_zone_id():
    r = requests.get("{}zones?name={}".format(BASE_URL, DOMAIN), headers={
        "X-Auth-Email": EMAIL,
        "X-Auth-Key": API_KEY,
        "Content-Type": "application/json"
    })
    return r.json()["result"][0]["id"]

def get_dns_record(zone_id):
    r = requests.get("{}zones/{}/dns_records?name={}.{}".format(BASE_URL, zone_id, SUBDOMAIN, DOMAIN), headers={
        "X-Auth-Email": EMAIL,
        "X-Auth-Key": API_KEY,
        "Content-Type": "application/json"
    })
    return r.json()["result"][0]

def update_dns_record(zone_id, dns_record, ip_address):
    dns_record["content"] = ip_address
    r = requests.put("{}zones/{}/dns_records/{}".format(BASE_URL, zone_id, dns_record["id"]),  headers={
        "X-Auth-Email": EMAIL,
        "X-Auth-Key": API_KEY,
        "Content-Type": "application/json"
    }, json=dns_record)
    return r.json()

def main():
    zone_id = get_zone_id()
    ip_address = get_ip_address()
    dns_record = get_dns_record(zone_id)
    return update_dns_record(zone_id, dns_record, ip_address)


if __name__ == "__main__":
    main()