Using the v2 API and my Home Computer to Automatically Update a Domain Name A Record (Like Dynamic DNS)

I want to have a script run automatically on my Mac at home, once an hour, to update the A record of a domain name which lives on DigitalOcean’s name servers.

I want the A record to be updated with whatever my external home IP address is (in effect, a dynamic DNS service so I can always get back to my home computer over the internet). My home computer sits behind a router supplied by my ISP.

I have been looking at the DigitalOcean API (v2) and using Terminal on my Mac I can successfully, manually, update the A record in question with the following command:

curl -X PUT -H "Content-Type: application/json" -H "Authorization: Bearer MY_API_ACCESS_TOKEN" -d '{"data":"IP_ADDRESS"}' "https://api.digitalocean.com/v2/domains/MY_DOMAIN/records/DOMAIN_ID_NUMBER"

What I’d like some help with, please, is how do I add to the above so that:

• My home external IP address gets ascertained when the script runs,
• Once ascertained, the IP address is automatically used (in place of ‘IP_ADDRESS’) in the above command, and,
• The command runs on its own, once an hour.

I’m quite new to all this so I’m sorry if I’m missing anything obvious.

Thanks, any help appreciated.