Cloudns - A Cloudflare Dynamic DNS Solution

A DNS record updater for Cloudflare's DNS API.

How it works

This script determines the the current IP address by querying the resolvers defined in the config file. It then queries the subdomains' A records off of Cloudflare and compares their IP addresses to the current IP address. Should the IP address of a subdomain's A record not match your current IP address it will be updated. The subdomain's A record will be created should it not already exist.

Notes

Every invocation of the script causes at least 1 request to a resolver specified and 1 API call to Cloudflare per domain. Updating a subdomain's A record is 1 API request per subdomain, even if they share the same domain. Resolvers are queried in the order specified until one returns a valid IP address. It is also possible to define a path to a file with the API key written in it. This is good for environments where the config file has to be shared like in a nix project.

Usage

First, get your User API Token from https://dash.cloudflare.com/profile/api-tokens. The token need the following permissions:

• Edit DNS

{
  "api": {
    "API Key": {
      "example.com": [ "@", "www", "sub1" ],
      "example.org": [ "@", "www", "sub1", "sub2" ]
    },
    "/path/to/a/file/containing/api_key": {
      "example.at": [ "sub1" ],
      "example.au": [ "sub1", "sub2" ]
    }
  },
  "resolvers": [
    "https://ifconfig.me/ip",
    "https://me.gandi.net"
  ],
  "log-path": "./log.jsonl"
}

Nix

Add this to the modules.

inputs = {
  cloudns.url = "git+https://git.krsnik.at/Kristian/cloudns";
};

outputs = {
  self,
  nixpkgs,
  cloudns
}: {
  ...
  modules = [
    cloudns.nixosModules.default
    {
      cloudns.enable = true;
      cloudns.timer = 300;
      cloudns.settings = {
        api = {
          "/path/to/a/file/containing/api_key" = {
            "example.com" = ["@" "www"];
          };
        };
        resolvers = [
          "https://ifconfig.me/ip"
          "https://me.gandi.net"
        ];
        log_path = "/path/to/log/file.jsonl";
      };
    }
    ...
  ];
  ...
}

Use cloudns.nixosModules.default for a NixOs module.

cloudns.timer specifies a timer in seconds when the script should be repeated.

Features

• Support for arbitrarily many domains and subdomains through a nested data structure.
• Small codebase
• Logging
• NixOS and home-manager modules

Limitations

• Only IPv4 addresses are supported