ddns.py is intended to be run as a service at intervals to check for changes of the IP address of the server the service is running on. If the IP address changes, the correspoding A records in Cloudflare will be updated.
The only user inputs are:
-
API_TOKEN- the Cloudflare API token - Created on Cloudfare web interface under My proifile -> API Tokens -> User API Tokens (versus API Keys) -
Zone IDs - 32 character identfiers - Found in Main Menu -> Websites -> then scroll down the right hand column.
ddns.py will check for a cache file, IP_Address_Cache.pkl, containing the A record IP addresses currently set on Cloudflare and their corresponding Cloudflare record IDs. If the file is absent or a new site has been added, ddns.py will query Cloudflare for the new information. Using the cache eliminates unneeded queries. If a site / recoard needs to be deleted, delete the cache file and remove the corresponding Zone ID from the zone_ids dictionary. The cache will be auto-populated the next time it runs.
If the reported IP address for the server does not match any of the cached values in the A record, the Cloudflare API call to update the DNS record will be performed.
To support automation of the script, I've created a systemd service and corresponding timer. For details see the following two sections.
Edit values of ExecStart and WorkingDirectory in ddns.service to match your setup.
Copy ddns.service into /etc/systemd/system as root:
sudo cp ddns.service /etc/systemd/system/ddns.service
Attempt to start the service using the following command:
sudo systemctl start ddns.service
Stop it using following command:
sudo systemctl stop ddns.service
To have it start automatically on reboot by using this command:
sudo systemctl enable ddns.service
The systemctl command can also be used to restart the service or disable it
Note the file prefix for the timer must match the prefix for the service. The timer is setup for running every 5 minutes.
Copy ddns.timer into /etc/systemd/system as root, for example:
sudo cp ddns.timer /etc/systemd/system/ddns.timer
Once this has been copied, the timer needs to be enabled:
sudo systemctl enable ddns.timer
Then the timer needs to be started:
sudo systemctl start ddns.timer
Check status with:
systemctl status ddns.service
Example status from working system:
● ddns.service - DDNS Client for Cloudflare Loaded: loaded (/etc/systemd/system/ddns.service; disabled; vendor preset: enabled) Active: inactive (dead) since Thu 2024-03-07 01:05:08 UTC; 48s ago TriggeredBy: ● ddns.timer Process: 251334 ExecStart=/usr/bin/python3 -u ddns.py --serviceMode (code=exited, status=0/SUCCESS) Main PID: 251334 (code=exited, status=0/SUCCESS)
Mar 07 01:05:08 odroid python3[251334]: 200 Mar 07 01:05:08 odroid python3[251334]: <Response [200]>
Query DNS records:
https://developers.cloudflare.com/api/operations/dns-records-for-a-zone-list-dns-records
Set DNS records:
https://developers.cloudflare.com/api/operations/dns-records-for-a-zone-update-dns-record
Some code and concept lifted from:
https://github.com/creimers/cloudflare-ddns
Python 3.8.10
The two Cloudfare interface calls are split and pretty easily isolated for testing; alhtough, they shouls just work. The curl command in the comments of ddns.py is a simple method to test out your zone IDs and API Token.
Once both the service and timer are running systemctl status ddns.service provides commpact but useful feedback on the state of the service including the time since it was last run. A simple metric to use when bringing up the service is to delete IP_Address_Cache.pkl as it will be regenerated if deleted every time the service is run.
It was acceptable and easisted for me to test the propagation by changing the DNS reecord through Cloudfare's web portal to an incorrect value and watch for the creation of IP_Address_Cache.pkl or the roll over of the timer from systemctl status ddns.service to check to see if the service correctly updated the A record.