defiant: Add domeneshop-dyndns

hosts/defiant/configuration.nix

@@ -16,6 +16,7 @@
       ./services/wireguard.nix
 
       # Services
+      ./services/dyndns.nix
       ./services/flame.nix
       ./services/gitea.nix
       ./services/hedgedoc.nix

hosts/defiant/services/dyndns.nix

@@ -0,0 +1,26 @@
+{ config, pkgs, lib, ... }:
+
+let
+  dnsname = "site3.feal.no";
+in {
+  # Defines DDNS_TOKEN and DDNS_SECRET from https://domene.shop/admin?view=api
+  sops.secrets."domeneshop/env" = { };
+
+  systemd.services.domeneshop-dyndns = {
+    serviceConfig.EnvironmentFile = config.sops.secrets."domeneshop/env".path;
+    startAt = "*/10 * * * *";
+
+    script = ''
+      DNSNAME="${dnsname}"
+      NEW_IP="$(${lib.getExe pkgs.curl} --silent https://ipinfo.io/ip)"
+      OLD_IP="$(${lib.getExe pkgs.getent} hosts "$DNSNAME" | ${lib.getExe pkgs.gawk} '{ print $1 }')"
+
+      if [[ "$NEW_IP" != "$OLD_IP" ]]; then
+        echo "Old IP ($OLD_IP) does not match new IP ($NEW_IP), updating..."
+        ${lib.getExe pkgs.curl} --silent "https://$DDNS_TOKEN:$DDNS_SECRET@api.domeneshop.no/v0/dyndns/update?hostname=$DNSNAME&myip=$NEW_IP"
+      else
+        echo "Old IP ($OLD_IP) matches new IP ($NEW_IP), exiting..."
+      fi
+    '';
+  };
+}