A simple program to update your ip-address for your gratisdns domain.
As with any go program, it is as simple as
go install
To cross compile it for a raspberry pi, do
GOOS=linux GOARCH=arm go build
instead.
You are required to provide gratisdns username, ddns password, one of your domains and a host on these (one of the entries in your A-records). The gratisdns service will automatically register the ip-address the update is coming from, so no need to figure this out yourself.
gratisddns -u <username> -p <ddns password> -h <domain> -p <host>
You can run this periodically either by adding it to your crontab or by having the program sending an update itself every nth hour by adding -s <n>.
If you are using this on a system with Systemd, you can use the provided unit file.