cfddns

#!/usr/bin/env python3

"""
Script to update this host's DNS entry on Cloudflare. Silently succeeds.
It requires you to have set the environment variables:

- CLOUDFLARE_API_KEY
- CLOUDFLARE_EMAIL
- CLOUDFLARE_HOSTNAME

The latter is the DDNS hostname. You can't add a hostname to a domain that
doesn't already exist. But once the domain exists, it will create the A record
if needed, or modify an existing A record.
"""

import os, json
from urllib.parse import urlencode
from urllib.request import urlopen
from collections import namedtuple

# The following environment variables MUST be set:
api_key = os.environ.get('CLOUDFLARE_API_KEY')
email = os.environ.get('CLOUDFLARE_EMAIL')
hostname = os.environ.get('CLOUDFLARE_HOSTNAME')

name, domain = hostname.split('.', 1)

class cloudflare:
  """simple cloudflare API client"""
  endpoint = "https://www.cloudflare.com/api_json.html"

  def __init__(self, api_key, email):
    self.api_key = api_key
    self.email = email
    
  def request(self, **params):
    response = urlopen(self.make_url(**params))
    data = json.loads(response.read().decode('utf8'))
    result = data['result']
    if result == 'success':
      return data['response']
    elif result == 'error':
      raise Exception("error: ", data['msg'])
    else:
      raise Exception("Unknown result: " + result)
  
  def make_url(self, **params):
    url = self.endpoint
    params['tkn'] = api_key
    params['email'] = email
    url += '?'
    url += urlencode(params)
    return url

client = cloudflare(api_key, email)

# Find the zone. This script won't create one.
zones = client.request(a="zone_load_multi")['zones']['objs']
zone = [z['zone_name'] for z in zones if z['zone_name'] == domain][0]
if not zone:
  raise Exception("Couldn't find zone: ", domain)

# Get the public IP address
ip = os.popen('dig +short myip.opendns.com @resolver1.opendns.com').read().strip()

# Create or update the record
recs = client.request(a='rec_load_all', z=zone)['recs']['objs']
rec_id = [r['rec_id'] for r in recs if r['name'] == hostname][0]
if rec_id:
  client.request(a='rec_edit', id=rec_id, type='A', name=name, ttl=1, z=zone, content=ip)
else:
  client.request(a='rec_new', type='A', name=name, z=zone, content=ip, ttl=1)