Cloudflare DNS Updater

A simple tool for automatically updating Cloudflare DNS entries on external IP changes, using the Cloudflare API. This is useful when your ISP is unable to provide you with a static IP address.

It does this by talking to an external site which echoes the IP address the request was made from. There are a lot of such services available for free, but some of them respond with random IP addresses when queried without a "valid" browser User-Agent.

Please be a good netizen and find yourself a service that is okay with scripting, or host a script somewhere yourself.

Building

This is really simple if you have a somewhat modern version of Go installed.

go build

This should result in a new binary named cloudflare-dns-updater in your current directory.

Configuration

1. Create a new config file:

cp config.json.example config.json

2. Populate the configuration file according to your needs.

{
    "cloudflare": {
        "api_token": "abc123abc123abc123abc123abc123abc123a",
        "email":    "[email protected]",
        "zone_id":   "abc123abc123abc123abc123abc123ab",
        "zone_name": "your.domain.com"
    },
    "ip_lookup_url": "https://domain.com/whats-my-ip",
    "sleep_seconds": 60,
    "verbose_mode": false
}

Notes on configuration

The details required for the Cloudflare API can be found in the Cloudflare API documentation .

Key	Description
ip_lookup_url	The URL to query for your external IP. The first IPv4 address found on the page will be used.
sleep_seconds	The sleep time between external IP checks. Only used if running in watch mode.
verbode_mode	Log more details to stdout. Can be enabled by the -v flag even if set to false.

Flags

Usage of ./cloudflare-dns-updater:
  -c string
    	Path to config file (default "./config.json")
  -v	Verbose mode
  -w	Keep watching for external IP change