Dynamic DNS for gandi.net

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README.md

DynGanDiNS

Dynamic DNS for gandi.net

How it works

curl external IP from icanhazip.com
curl to update the configured domain and record on Gandi via the API
Unless the IP has not changed (compared to previous check at /tmp/DynGanDiNS.ip)
Bash without the isms. Portability aimed.
systemd timer included!

How to use

Acquire an API key from Gandi by visiting your account page and finding the authorized apps UI to generate one. Then clone this repo locally. Update Settings.env with your API key, domain and record name and then run make install (sudo as needed). After installation the environment variables are sourced from /etc/sysconfig/DynGanDiNS which will look like this (but hopefully with your info by now not empty variables):

GDDNS_API_KEY= # API key from Gandi
GDDNS_DOMAIN= # the domain name to update. example.com
GDDNS_RECORD_NAME= # the record to update. ex. raspi
# GDDNS_TTL="3600"

If not using the systemd timer/service then you'll have to supply the environment variables some other way. Also probably don't bother with make install just use DynGanDiNS.sh how you please.

Script

After make install the shell script is available in your path (from /bin) as DynGanDiNS and you can run that to make sure the environment is properly configured before enabling the timer and walking away.

Timer

By default the timer is configured to run the service every hour. Use systemctl edit DynGanDiNS.timer to override OnCalendar as desired.

# do this after having updated Settings.env and running `make install`
systemctl enable --now DynGanDiNS.timer

If you already ran the install then the settings are here: /etc/sysconfig/DynGanDiNS

Why?

Internet service providers (ISPs) may or may not provide a static IP address for your connection to the World Wide Web. When they do not then it is dynamic which poses a problem for domain name resolution (DNS) trying to associate the name with an IP that might change. To work around this some way of getting the current IP address and telling the DNS about it is required—ideally exactly and only when the IP changes.

This problem is very common for home computers wanting to expose services behind DNS to the larger network. For example a Raspberry Pi hosting an artisinal handcrafted website about knitting and gardening. Or maybe a Wireguard VPN exposing an instance of Pi-hole for ad-block on the go!. Or any other reason a server could be useful and you'd rather own instead of rent it.