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+#+title: Dynamic DNS with Njalla API
+#+date: 2022-02-10
+#+description: Learn how to dynamically update DNS records for changing IPs with Njalla.
+#+filetags: :sysadmin:
+
+* Njalla's API
+As noted in my recent post about [[/blog/ditching-cloudflare/][switching
+to Njalla from Cloudflare]], I was searching for a way to replace my
+very easy-to-use bash script to [[/blog/cloudflare-dns-api/][update
+Cloudflare's DNS via their 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 [[https://njal.la/settings/api/][API Settings]] 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
+[[https://njal.la/api/][Njalla API Documentation]].
+
+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:
+
+#+begin_src txt
+params: {
+    domain: string
+}
+#+end_src
+
+The =edit-record= request requires the following payload to be sent when
+calling the API:
+
+#+begin_src txt
+params: {
+    domain: string
+    id: int
+    content: string
+}
+#+end_src
+
+* 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:
+
+#+begin_src sh
+mkdir ~/ddns
+#+end_src
+
+Next, create a Python script file:
+
+#+begin_src sh
+nano ~/ddns/ddns.py
+#+end_src
+
+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.
+
+#+begin_src 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)
+#+end_src
+
+** Running the Script
+Once you've created the script and are ready to test it, run the
+following command:
+
+#+begin_src sh
+python3 ~/ddns/ddns.py
+#+end_src
+
+** 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:
+
+#+begin_src sh
+crontab -e
+#+end_src
+
+In the cron file, paste the following at the bottom of the editor in
+order to check the IP every five minutes:
+
+#+begin_src sh
+,*/5 ** ** ** ** python3 /home/<your_username>/ddns/ddns.py
+#+end_src