Added njalla ddns

nixarr/default.nix

@@ -69,6 +69,46 @@ in {
       '';
     };
 
+    ddns.njalla = {
+      enable = mkOption {
+        type = types.bool;
+        default = false;
+        description = ''
+          **Required options:**
+
+          - [`nixarr.ddns.njalla.keysFile`](#nixarr.ddns.njalla.keysfile)
+
+          Whether or not to enable DDNS for a [Njalla](https://njal.la/)
+          domain.
+        '';
+      };
+
+      keysFile = mkOption {
+        type = with types; nullOr path;
+        default = null;
+        description = ''
+          A path to a JSON-file containing key value pairs of domains and keys.
+
+          To get the keys, create a dynamic njalla record. Upon creation
+          you should see something like the following command suggested:
+
+          ```
+            curl "https://njal.la/update/?h=jellyfin.example.com&k=zeubesojOLgC2eJC&auto"
+          ```
+
+          Then the JSON-file you give here should be:
+
+          ```json
+            {
+              "jellyfin.example.com": "zeubesojOLgC2eJC"
+            }
+          ```
+
+          You can, of course, add more key-value pairs than just one.
+        '';
+      };
+    };
+
     vpn = {
       enable = mkOption {
         type = types.bool;
@@ -146,6 +186,13 @@ in {
           to be set, but it was not.
         '';
       }
+      {
+        assertion = cfg.ddns.njalla.enable -> cfg.ddns.njalla.keysFile != null;
+        message = ''
+          The nixarr.ddns.njalla.enable option requires the
+          nixarr.ddns.njalla.keysFile option to be set, but it was not.
+        '';
+      }
     ];
 
     users.groups = {
@@ -231,4 +278,60 @@ in {
       openUdpPorts = cfg.vpn.openUdpPorts;
     };
   };
+
+  systemd = let 
+    ddns-njalla = pkgs.writeShellApplication {
+      name = "ddns-njalla";
+
+      runtimeInputs = with pkgs; [ curl jq ];
+
+      # Thanks chatgpt...
+      text = ''
+        # Path to the JSON file
+        json_file="${cfg.ddns.njalla.keysFile}"
+
+        # Convert the JSON object into a series of tab-separated key-value pairs using jq
+        # - `to_entries[]`: Convert the object into an array of key-value pairs.
+        # - `[.key, .value]`: For each pair, create an array containing the key and the value.
+        # - `@tsv`: Convert the array to a tab-separated string.
+        # The output will be a series of lines, each containing a key and a value separated by a tab.
+        jq_command='to_entries[] | [.key, .value] | @tsv'
+
+        # Read the converted output line by line
+        # - `IFS=$'\t'`: Use the tab character as the field separator.
+        # - `read -r key val`: For each line, split it into `key` and `val` based on the tab separator.
+        while IFS=$'\t' read -r key val; do
+          # For each key-value pair, execute the curl command
+          # Replace `''${key}` and `''${val}` in the URL with the actual key and value.
+          curl "https://njal.la/update/?h=''${key}&k=''${val}&auto"
+        done < <(jq -r "$jq_command" "$json_file")
+      '';
+    };
+  in mkIf cfg.ddns.njalla.enable {
+    timers = {
+      ddnsNjalla = {
+        Unit.Description = "Timer for setting the njalla DDNS records";
+
+        Timer = {
+          OnBootSec = "5min"; # Run 5 minutes after system boot
+          OnCalendar = "hourly";
+          Persistent = "true"; # Run service immediately if last window was missed
+          RandomizedDelaySec = "5min"; # Run service OnCalendar +- 5min
+        };
+
+        Install.WantedBy = ["timers.target"];
+      };
+    };
+
+    services = {
+      ddnsNjalla = {
+        Unit.Description = "Sets the njalla DDNS records";
+
+        Service = {
+          ExecStart = getExe ddns-njalla;
+          Type = "oneshot";
+        };
+      };
+    };
+  };
 }