python3 script to update freedns dynamic dns with logging.

freedns_update.py

# Put this somewhere on your server, such as ~/scripts/freedns/freedns_update.py
# You can test by running it manually with 
#    python3 ~/scripts/freedns/freedns_update.py
# and you can check the log at ~/scripts/freedns/log.txt
# To automatically run the script, add this line to your crontab:
# 0 9 * * * python3 ~/scripts/freedns/freedns_update.py
# this will update the ip address every day at 9am.

# Domains that should point to the current IP
freedns_domains = set(["mysubdomain.mydomain.com"])

# FreeDNS API endpoint, accessible from https://freedns.afraid.org/api/ (use the ASCII one)
freedns_check_url = "https://freedns.afraid.org/api/?action=getdyndns&sha=API_KEY_GOES_HERE"

# It is assumed that this address responds with a page containing only the IP address
# alternative: https://wtfismyip.com/text
ip_check_url = "https://ident.me/"


import logging
logging.basicConfig(filename="log.txt",
                    level=logging.DEBUG,
                    format="%(asctime)s:   %(message)s",
                    datefmt="%m/%d/%Y %I:%M:%S")
logging.info("")
logging.info("Script executing...")

import urllib.request
current_ip = urllib.request.urlopen(ip_check_url).read().decode("utf-8")
logging.info("Current IP is " + current_ip)

logging.info("Getting FreeDNS records...")
import urllib.request
records_raw = urllib.request.urlopen(freedns_check_url).read().decode("utf-8").split("\n")
logging.info("Found " + str(len(records_raw)) + ".")

for raw_record in records_raw:
    domain, current_freedns_ip, freedns_update_url = raw_record.split("|")

    if domain not in freedns_domains:
        logging.info(domain + " is not on the watch list, skipping.")
    else:
        logging.info(domain + " (" + current_freedns_ip + ") is on the watch list.")

        if current_ip == current_freedns_ip:
            logging.info("IPs already match.")
        else:
            logging.info("IPs don't match, updating...")
            urllib.request.urlopen(freedns_update_url)
            logging.info("Done.")

logging.info("Script exited gracefully.")