Netlify DDNS

A lightweight Python script that implements Dynamic DNS (DDNS) for domains managed by Netlify. It automatically keeps a DNS A record (IPv4) and AAAA record (IPv6) pointed at the current public IP address of the machine running it. No paid DDNS service required.

How it works

On each run the script:

1. Fetches the machine's current public IPv4 and IPv6 addresses from ipify
2. Retrieves all DNS records for the configured domain from the Netlify API
3. For each record type (A / AAAA):
   • Creates the record if it does not exist
   • Replaces it if the IP has changed
   • Does nothing if it is already up to date
4. Writes a timestamped entry to netlify_ddns.log

IPv6 is handled gracefully: if the machine has no public IPv6 address the AAAA update is skipped with a warning and the script continues normally.

Requirements

• Python 3.9+
• A domain registered with Netlify as the DNS provider
• A Netlify personal access token with DNS write permissions (create one here)

Installation

git clone https://github.com/johnsmol/netlify-ddns.git
cd netlify-ddns
python -m venv venv
source venv/bin/activate        # Windows: venv\Scripts\activate
pip install -r requirements.txt

Configuration

Copy the example environment file and fill in your values:

cp example.env .env

.env contents:

FQDN="home.example.com"
NETLIFY_API_TOKEN="your-netlify-api-token"

Variable	Description
FQDN	The fully-qualified domain name to keep updated (e.g. home.example.com)
NETLIFY_API_TOKEN	Netlify personal access token with DNS write permissions

The record does not need to exist beforehand — the script creates it on the first run.

Running manually

python main.py

Output is written to netlify_ddns.log in the same directory. Logs rotate daily with a two-day retention window.

Deploying on Ubuntu Server with cron

The recommended setup is to run the script every 5 minutes via cron. The Netlify API is rate-limited to 500 requests per minute; one execution every 5 minutes is well within that limit.

1. Clone and install

cd /opt
sudo git clone https://github.com/johnsmol/netlify-ddns.git
sudo chown -R $USER:$USER /opt/netlify-ddns
cd /opt/netlify-ddns
python3 -m venv venv
source venv/bin/activate
pip install -r requirements.txt
deactivate

2. Configure

cp /opt/netlify-ddns/example.env /opt/netlify-ddns/.env
nano /opt/netlify-ddns/.env

3. Test the script

/opt/netlify-ddns/venv/bin/python /opt/netlify-ddns/main.py
cat /opt/netlify-ddns/netlify_ddns.log

Confirm that the log shows a successful run before enabling the cron job.

4. Add the cron job

Open the crontab editor:

crontab -e

Add the following line:

*/5 * * * * /opt/netlify-ddns/venv/bin/python /opt/netlify-ddns/main.py

Save and exit. Verify the job is registered:

crontab -l

5. Monitor

# Follow the log in real time
tail -f /opt/netlify-ddns/netlify_ddns.log

# Check the last recorded IP update
grep "created successfully" /opt/netlify-ddns/netlify_ddns.log | tail -5

Development

Install development dependencies (includes pytest):

pip install -r requirements-dev.txt

Run the test suite:

python -m pytest tests/ -v

Logging

All runs append to netlify_ddns.log in the project directory. The log rotates daily and retains the two most recent files. Each entry follows the format:

2024-11-01 12:00:01,234 - netlify_ddns - INFO - System current public IPv4 address is: 1.2.3.4
2024-11-01 12:00:01,891 - netlify_ddns - INFO - A record already up-to-date for hostname: home.example.com

License

MIT — see LICENSE.md.