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+date = 2022-06-04
+title = "Dynamic DNS with Njalla API"
+description = "Learn how to update Njalla DNS records automatically with a simple Python script."
+draft = false
++++
+
+## Njalla's API
+
+As noted in my recent post about
+[switching to Njalla from Cloudflare](/blog/ditching-cloudflare/), I was
+searching for a way to replace my very easy-to-use bash script to
+[update Cloudflare's DNS via their API](/blog/cloudflare-dns-api/).
+
+To reiterate what I said in those posts, this is a common necessity for those of
+us who have non-static IP addresses that can change at any moment due to ISP
+policy.
+
+In order to keep a home server running smoothly, the server admin needs to have
+a process to constantly monitor their public IP address and update their
+domain's DNS records if it changes.
+
+This post explains how to use Python to update Njalla's DNS records whenever a
+machine's public IP address changes.
+
+### Creating a Token
+
+To use Njalla's API, you will first need to create a token that will be used to
+authenticate you every time you call the API. Luckily, this is very easy to do
+if you have an account with Njalla.
+
+Simply go the [API Settings](https://njal.la/settings/api/) page and click the
+`Add Token` button. Next, enter a name for the token and click `Add`.
+
+Finally, click the `Manage` button next to your newly created token and copy the
+`API Token` field.
+
+### Finding the Correct API Request
+
+Once you have a token, you're ready to call the Njalla API for any number of
+requests. For a full listing of available requests, see the
+[Njalla API Documentation](https://njal.la/api/).
+
+For this demo, we are using the `list-records` and `edit-record` requests.
+
+The `list-records` request requires the following payload to be sent when
+calling the API:
+
+```txt
+params: {
+    domain: string
+}
+```
+
+The `edit-record` request requires the following payload to be sent when calling
+the API:
+
+```txt
+params: {
+    domain: string
+    id: int
+    content: string
+}
+```
+
+## Server Set-Up
+
+To create this script, we will be using Python. By default, I use Python 3 on my
+servers, so please note that I did not test this in Python 2, and I do not know
+if Python 2 will work for this.
+
+### Creating the Script
+
+First, find a suitable place to create your script. Personally, I just create a
+directory called `ddns` in my home directory:
+
+```sh
+mkdir ~/ddns
+```
+
+Next, create a Python script file:
+
+```sh
+nano ~/ddns/ddns.py
+```
+
+The following code snippet is quite long, so I won't go into depth on each part.
+However, I suggest you read through the entire script before running it; it is
+quite simple and contains comments to help explain each code block.
+
+:warning: **Note**: You will need to update the following variables for this to
+work:
+
+-   `token`: This is the Njalla API token you created earlier.
+-   `user_domain`: This is the top-level domain you want to modify.
+-   `include_subdomains`: Set this to `True` if you also want to modify
+    subdomains found under the TLD.
+-   `subdomains`: If `include_subdomains` = `True`, you can include your list of
+    subdomains to be modified here.
+
+```python
+#!/usr/bin/python
+# -*- coding: utf-8 -*-
+# Import Python modules
+
+from requests import get
+import requests
+import json
+
+# Set global variables
+
+url = 'https://njal.la/api/1/'
+token = '<your-api-token>'
+user_domain = 'example.com'
+include_subdomains = True
+subdomains = ['one', 'two']
+
+
+# Main API call function
+
+def njalla(method, **params):
+    headers = {'Authorization': 'Njalla ' + token}
+    response = requests.post(url, json={'method': method,
+                             'params': params}, headers=headers).json()
+    if 'result' not in response:
+        raise Exception('API Error', response)
+    return response['result']
+
+
+# Gather all DNS records for a domain
+
+def get_records(domain):
+    return njalla('list-records', domain=user_domain)
+
+
+# Update a DNS record for a domain
+
+def update_record(domain, record_id, record_content):
+    return njalla('edit-record', domain=domain, id=record_id,
+                  content=record_content)
+
+
+# Get public IP addresses
+
+ipv4 = get('https://api.ipify.org').text
+print('IPv4: {}'.format(ipv4))
+ipv6 = get('https://api64.ipify.org').text
+print('IPv6: {}'.format(ipv6))
+
+# Call API to get all DNS records
+
+data = get_records(user_domain)
+
+# Loop through records and check if each one is IPv4 (A) or IPv6 (AAAA)
+# Update only if DNS is different from server IP
+
+for record in data['records']:
+    if record['name'] == '@' or (include_subdomains and record['name'] \
+        in subdomains):
+        if record['type'] == 'A':
+            if record['content'] == ipv4:
+                print(record['type'], 'record for', record['name'],
+                      'already matches public IPv4 address. Skipping...'
+                      )
+            else:
+                print('IPv4 of', ipv4,
+                      'does not match Njalla\'s value of',
+                      record['content'], '. Updating...')
+                update_record(user_domain, record['id'], ipv4)
+        elif record['type'] == 'AAAA':
+            if record['content'] == ipv6:
+                print(record['type'], 'record for', record['name'],
+                      'already matches public IPv6 address. Skipping...'
+                      )
+            else:
+                print('IPv6 of', ipv6,
+                      'does not match Njalla\'s value of',
+                      record['content'], '. Updating...')
+                update_record(user_domain, record['id'], ipv6)
+```
+
+### Running the Script
+
+Once you've created the script and are ready to test it, run the following
+command:
+
+```sh
+python3 ~/ddns/ddns.py
+```
+
+### Setting the Script to Run Automatically
+
+To make sure the scripts run automatically, add it to the `cron` file so that it
+will run on a schedule. To do this, open the `cron` file:
+
+```sh
+crontab -e
+```
+
+In the cron file, paste the following at the bottom of the editor in order to
+check the IP every five minutes:
+
+```sh
+*/5 * * * * python3 /home/<your_username>/ddns/ddns.py
+```