dns2ip-templater: A simple tool for resolving DNS records and templating output

dns2ip-templater is a command-line tool designed to resolve DNS records and use the resulting IP addresses to render a user-defined template. This allows you to easily and dynamically configure configurations, scripts, or other files based on the current DNS records.

It gives the possibility to run the tool once for cron tasks or as a daemon with an interval between each rendering.

In my personal use-case, I use dns2ip-templater to dynamically update the configuration of a Traefik middleware (IPAllowList) because some services are reachable via a dynamic IP.

Installation

You can install by using the binaries available on the releases page.

You can also install it directly on your machine by typing:

go install github.com/themimitoof/dns2ip-templater

Usage

dns2ip-templater requires a configuration file and a template. By default, the config file path is config.yml, the template path is template.tmpl. Use the flag --help to check the default value and how to override it:

$ dns2ip-templater --help
Usage of dns2ip-templater:
  -conf string
        Configuration file path (default "config.yml")
  -interval duration
        Define the interval to run the routine (by default: executed once)
  -output string
        Rendered file path (default "output.txt")
  -template string
        Template file path (default "template.tmpl")

In the configuration file config.yml, you need to specify at least a list of services like my-house.net. You can also specify IPs and subnets by using ranges. Here's an example:

services:
  - my-house.duckdns.org
  - home.themimitoof.fr

ranges:
  - 8.8.8.8
  - 192.168.1.0/24

In a template.tmpl file, add your content and make a range like this one in the following example:

http:
  middlewares:
    no-server-header:
      headers:
        customResponseHeaders:
          Server: ""
    internal_only:
      IPAllowList:
        rejectStatusCode: 200
        sourceRange:
          {{- range $service, $ips := . }}
            # {{ $service }}
            {{- range $ip := $ips}}
            - {{ $ip }}
            {{- end}}
          {{- end }}

To run dns2ip-templater, simply execute the command dns2ip-templater and take a look on the output.txt file.

$ dns2ip-templater
$ cat output.txt
http:
  middlewares:
    internal_only:
      IPAllowList:
        rejectStatusCode: 200
        sourceRange:
            # Ranges
            - 8.8.8.8
            - 1.1.1.1
            # google.com
            - 2a00:1450:4007:819::200e
            - 142.250.178.142
            # themimitoof.fr
            - 2606:4700:3031::ac43:8201
            - 2606:4700:3032::6815:30a
            - 104.21.3.10
            - 172.67.130.1

You can override the path and the name of the output file by using the -output flag.

In case you want to run dns2ip-templater as a daemon, use the -interval flag with a Go duration in parameter:

$ dns2ip-templater -interval 1h -output /traefik/config/dyn-conf/internal-only-middleware.conf
Executing new iteration of dns2ip-templater... Done.

Licenses

This project is released under the MIT license. Feel free to use, contribute, fork and do what you want with it. Please keep all licenses, copyright notices and mentions in case you use, re-use, steal, fork code from this repository. </rewrite_this>