feat: Implement NixOS modules for madd server and client

flake.nix

@@ -40,7 +40,13 @@
       overlays.madd = final: prev: mkPackages final;
       overlays.default = overlays.madd;
 
-      nixosModules.madd = import ./nixos.nix { overlay = overlays.madd; };
+      nixosModules.madd = {
+        imports = [
+          ./modules/madd-client.nix
+          ./modules/madd-server.nix
+        ];
+        config.nixpkgs.overlays = [ overlays.default ];
+      };
       nixosModules.default = nixosModules.madd;
     };
 }

modules/madd-client.nix

@@ -0,0 +1,72 @@
+{
+  lib,
+  pkgs,
+  config,
+  ...
+}:
+
+with lib;
+let
+  cfg = config.services.madd-client;
+in
+{
+  options.services.madd-client = {
+    enable = mkEnableOption "MADD client";
+    endpoint = mkOption {
+      type = types.str;
+      description = "Endpoint for MADD client to connect to.";
+    };
+    interface = mkOption {
+      type = types.str;
+      description = "Network interface to use for MADD client.";
+    };
+    priv-key-file = mkOption {
+      type = types.str;
+      default = "/etc/ssh/ssh_host_ed25519_key";
+      description = "Path to the private SSH key file identifying this machine.";
+    };
+    pub-key-file = mkOption {
+      type = types.str;
+      default = "${config.services.madd-client.priv-key-file}.pub";
+      description = "Path to the public SSH key file identifying this machine.";
+    };
+    hostname = mkOption {
+      type = types.str;
+      default = config.networking.hostName;
+      description = "Hostname to use for MADD client.";
+    };
+  };
+
+  config = mkIf cfg.enable {
+    systemd.services.madd-client = {
+      description = "MADD Client Service";
+      wantedBy = [ "multi-user.target" ];
+      after = [ "network-online.target" ];
+      requires = [ "network-online.target" ];
+      script = ''
+        function run_update {
+          ipv4=$(${pkgs.iproute2}/bin/ip -4 addr show dev "${cfg.interface}" | grep -Po 'inet \K[\d.]+' || true)
+          if [ -n "$ipv4" ]; then
+
+            export MADD_ENDPOINT="${cfg.endpoint}";
+            export MADD_PRIV_KEY="${cfg.priv-key-file}";
+            export MADD_PUB_KEY="${cfg.pub-key-file}";
+            export MADD_HOSTNAME="${cfg.hostname}";
+            export MADD_IP="$ipv4";
+
+            ${pkgs.madd-client}/bin/madd-client 2>/dev/null ;
+          fi
+        }
+
+        run_update
+
+        ${pkgs.iproute2}/bin/ip -4 monitor address label dev "${cfg.interface}" | while read -r event; do
+          if [[ $event == \[ADDR\]* ]]; then
+            echo "Detected address change"
+            run_update
+          fi
+        done
+      '';
+    };
+  };
+}

modules/madd-server.nix

@@ -0,0 +1,79 @@
+{
+  lib,
+  pkgs,
+  config,
+  ...
+}:
+
+with lib;
+let
+  cfg = config.services.madd-server;
+in
+{
+  options.services.madd-server = {
+    enable = mkEnableOption "MADD server";
+    settings = {
+      bind = mkOption {
+        type = types.str;
+        default = "0.0.0.0:5301";
+        description = "Address and port for MADD server to bind to.";
+      };
+      zone = mkOption {
+        type = types.str;
+        example = "lan.example.com";
+        description = "DNS zone under which the hosts are registered.";
+      };
+      networks = mkOption {
+        type = types.listOf types.str;
+        default = [ ];
+        example = [ "10.0.0.0/8" ];
+        description = "List of subnets to which hostnames can be registered.";
+      };
+      registration_limit = mkOption {
+        type = types.int;
+        default = 1;
+        description = "Maximum number of hostnames a single host can register.";
+      };
+      dns_server = mkOption {
+        type = types.str;
+        example = "localhost:53";
+        description = "DNS server to use. Must support dynamic updates.";
+      };
+      tsig_key_name = mkOption {
+        type = types.str;
+        default = "madd";
+        description = "TSIG key name for DNS updates.";
+      };
+      tsig_key_file = mkOption {
+        type = types.str;
+        default = "/etc/madd/tsig.key";
+        description = "Path to the TSIG key file for DNS updates. Must be encoded in base64.";
+      };
+      tsig_algorithm = mkOption {
+        type = types.str;
+        default = "hmac-sha256";
+        description = "TSIG algorithm to use for DNS updates.";
+      };
+      data_dir = mkOption {
+        type = types.str;
+        default = "/var/lib/madd";
+        description = "Directory where MADD server stores its data.";
+      };
+    };
+  };
+
+  config = mkIf cfg.enable {
+    environment.etc."madd/madd.toml".source = (pkgs.formats.toml { }).generate "madd.toml" cfg.settings;
+
+    systemd.services.madd-server = {
+      description = "MADD Server Service";
+      wantedBy = [ "multi-user.target" ];
+      after = [ "network-online.target" ];
+      requires = [ "network-online.target" ];
+      serviceConfig = {
+        ExecStart = "${pkgs.madd-server}/bin/madd-server";
+        Restart = "on-failure";
+      };
+    };
+  };
+}

nixos.nix

@@ -1,78 +0,0 @@
-{ overlay }:
-
-{
-  lib,
-  pkgs,
-  config,
-  ...
-}:
-
-with lib;
-{
-  options.services.madd-client = {
-    enable = mkEnableOption "MADD client";
-    endpoint = mkOption {
-      type = types.str;
-      description = "Endpoint for MADD client to connect to.";
-    };
-    interface = mkOption {
-      type = types.str;
-      default = "eth0";
-      description = "Network interface to use for MADD client.";
-    };
-    priv-key-file = mkOption {
-      type = types.str;
-      default = "/etc/ssh/ssh_host_ed25519_key";
-      description = "Path to the private SSH key file identifying this machine.";
-    };
-    pub-key-file = mkOption {
-      type = types.str;
-      default = "${config.services.madd-client.priv_key_file}.pub";
-      description = "Path to the public SSH key file identifying this machine.";
-    };
-    hostname = mkOption {
-      type = types.str;
-      default = config.networking.hostName;
-      description = "Hostname to use for MADD client.";
-    };
-  };
-
-  options.services.madd-server = {
-    enable = mkEnableOption "MADD server";
-  };
-
-  config = {
-    nixpkgs.overlays = [ overlay ];
-  }
-  // (
-    let
-      cfg = config.services.madd-client;
-    in
-    optionalAttrs config.madd-client.enable {
-      systemd.services.madd-client = {
-        description = "MADD Client Service";
-        wantedBy = [ "multi-user.target" ];
-        before = [ "network-pre.target" ];
-        requires = [ "network-pre.target" ];
-        script = ''
-          ${pkgs.iproute2}/bin/ip -4 monitor address label dev "${cfg.interface}" | while read -r event; do
-            if [[ $event == \[ADDR\]* ]]; then
-              ipv4=$(${pkgs.iproute2}/bin/ip -4 addr show dev "${cfg.interface}" | grep -Po 'inet \K[\d.]+')
-              if [ -n "$ipv4" ]; then
-
-                export MADD_ENDPOINT="${cfg.endpoint}"
-                export MADD_PRIV_KEY="${cfg.priv-key-file}"
-                export MADD_PUB_KEY="${cfg.pub-key-file}"
-                export MADD_HOSTNAME="${cfg.hostname}"
-                export MADD_IP="$ipv4"
-
-                ${pkgs.madd-client}/bin/madd-client
-              fi
-          done
-        '';
-      };
-    }
-  )
-  // (optionalAttrs config.madd-server.enable {
-  });
-}

src/dns.rs

@@ -267,6 +267,9 @@ async fn init_dns_registrations(
 async fn write_registrations(registrations: &Registrations, config: &Config) {
     let path = config.data_dir.join("registrations.toml");
     let contents = toml::to_string(registrations).unwrap();
+    if !config.data_dir.exists() {
+        tokio::fs::create_dir_all(&config.data_dir).await.unwrap();
+    }
     tokio::fs::write(path, contents).await.unwrap();
 }