r53.go

This script, written in golang acts as its own pseudo-ddns provider. It uses the AWS v2 golang sdk to update a DNS record in Route 53 to point to a given IP address.

Pre-requisites:

You must have an IAM account with api credentials and permissions to update the Route53 records in question, ie.:

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Sid": "AllowUpdateDns",
            "Effect": "Allow",
            "Action": "route53:ChangeResourceRecordSets",
            "Resource": "*"
        }
    ]
}

Place your IAM credentials in ~/.aws/credentials on the service which is running this script. eg.

[default]
aws_access_key_id=AK****************YU
aws_secret_access_key=pQ***************************************tq

Building & running the script on your own server

The compiled executable for linux r53-ddns is already included in this repo and is ready to use, so if you prefer to use that, ignore the first 3 steps:

1. Ensure you have golang installed @ minimum version 1.19
2. go mod tidy
3. go build
4. Copy the compiled r53-ddns file to your server/router where you want it to run (in my case, it's a GL.inet Flint router with OpenWRT) a. You can use scp for this, eg: scp r53-ddns [email protected]:/root/r53-ddns
5. SSH into the server and run ./r53-ddns (see below for args)

Usage

To use this script, you need to provide the following arguments:

• zone_id: The ID of the hosted zone in Route 53 where you want to update the DNS record.
• hostname: The hostname of the DNS record you want to update.
• ip_address: The IP address you want to set for the DNS record.

Here's an example of how to use the script:

./r53 <zone_id> <hostname> <ip_address> | tee -a /root/ddns-output.log

To set this up to be executed regularly, you can set a cron job with crontab -e:

0 */6 * * * /root/r53 Z000000000000000000MW home.foo.bar $(/root/get-ip.sh) | tee -a /root/ddns-output.log
   ^             ^                                                 ^              
   |             |                                                 |
   |             this is the path to the r53 executable script     |
   |                                                               this is a local script which gets the
   |                                                               current public ip address of the server
   |                                                               (see comments in `get-ip.sh`)
   this cron job will run every 6 hours