Cloudflare Dynamic IP

cf-dynamic-ip.service

[Unit]
Description=Update DNS record on Cloudflare

[Service]
ExecStart=/usr/bin/python /opt/cf.py
DynamicUser=yes
LoadCredentialEncrypted=cf-api-token:/etc/cf-api-token

[Install]
WantedBy=network.target

cf-dynamic-ip.timer

[Unit]
Description=Run external IP update every hour

[Timer]
OnBootSec=10
OnUnitActiveSec=1h

[Install]
WantedBy=timers.target

cf.py

import os, sys, json
import requests
import dns.resolver

# See systemd's LoadCredentialEncrypted= option
f_cf_token = open(os.path.join(os.environ.get('CREDENTIALS_DIRECTORY'), 'cf-api-token'))
cf_token = f_cf_token.read()
f_cf_token.close()

cf_api_base  = 'https://api.cloudflare.com/client/v4'
cf_zone_id   = 'ab28ab290e92f20997573aa238bbd203'
cf_record_id = 'ee2839bcd2394bee22f349375dea32db'

if not cf_token:
	sys.stderr.write('CF_TOKEN not set. Exiting.\n')
	sys.exit(1)

# Discover external IP address using myip.opendns.com
resolver = dns.resolver.Resolver(configure=False)
resolver.nameservers = ['208.67.222.222', '208.67.220.220']
external_ip = resolver.resolve('myip.opendns.com', 'A')[0].address
print(f'Discovered external IP address {external_ip}')
 
res = requests.patch(
	f'{cf_api_base}/zones/{cf_zone_id}/dns_records/{cf_record_id}',
	headers={'Authorization': f'Bearer {cf_token}'},
	data=json.dumps({'content': external_ip})
)

if res.status_code == 200:
	print('Cloudflare API request successful')
	sys.exit(0)
else:
	sys.stderr.write('Cloudflare API request failed\n')
	sys.stderr.write(res.text)
	sys.exit(1)