feat(services): add valheim server module and preset

platforms/nixos/modules/nmasur/presets/services/valheim/valheim-password.age

@@ -0,0 +1,16 @@
+-----BEGIN AGE ENCRYPTED FILE-----
+YWdlLWVuY3J5cHRpb24ub3JnL3YxCi0+IHNzaC1lZDI1NTE5IE1nSGFPdyA5V29j
+dWc3Rmd2T3hHdkNlSE1nejVKdGY0UkUxM2U4eStQWEk5Z2pLOXlVCkExWWhzMzZZ
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+V0dNSWh2YVRya1o5US9nSURSZwpXSHFhdTBOVExxSlhsYlRnWTR4Y1ZURWlCK2pG
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+Y1ZxeE8wSkVpRllTT29QZTQ3L25ReGZ6WEMzSnZvSGJQaUNNV2J4ZzNzYwp3Ll3z
+WxwIP3+BEVkWO52W77uZVfS9it6ecqvcFmEQK0PCzrKsTkm5Xlw3mAp42kXeIg==
+-----END AGE ENCRYPTED FILE-----

platforms/nixos/modules/nmasur/presets/services/valheim/valheim.nix

@@ -0,0 +1,90 @@
+{
+  config,
+  pkgs,
+  lib,
+  ...
+}:
+
+let
+  inherit (config.nmasur.settings) hostnames;
+  cfg = config.nmasur.presets.services.valheim;
+in
+
+{
+
+  options.nmasur.presets.services.valheim = {
+    enable = lib.mkEnableOption "Valheim dedicated server";
+
+    serverName = lib.mkOption {
+      type = lib.types.str;
+      default = "Midgard";
+      description = "Server name in server browser.";
+    };
+
+    worldName = lib.mkOption {
+      type = lib.types.str;
+      default = "Midgard";
+      description = "World save name.";
+    };
+
+    port = lib.mkOption {
+      type = lib.types.port;
+      default = 2456;
+      description = "Server port.";
+    };
+
+    crossplay = lib.mkOption {
+      type = lib.types.bool;
+      default = false;
+      description = "Enable cross-platform play.";
+    };
+
+    openFirewall = lib.mkOption {
+      type = lib.types.bool;
+      default = true;
+      description = "Open UDP ports in firewall.";
+    };
+
+    passwordFile = lib.mkOption {
+      type = lib.types.path;
+      default = ./valheim-password.age;
+      description = "Age-encrypted secret file containing the server password.";
+    };
+  };
+
+  config = lib.mkIf cfg.enable {
+
+    allowUnfreePackages = [
+      "valheim-server"
+      "steamworks-sdk-redist"
+    ];
+
+    secrets.valheim-password = {
+      source = cfg.passwordFile;
+      dest = "${config.secretsDirectory}/valheim-password";
+      owner = "valheim";
+      group = "valheim";
+      permissions = "0400";
+    };
+
+    systemd.services.valheim-password-secret = {
+      requiredBy = [ "valheim.service" ];
+      before = [ "valheim.service" ];
+    };
+
+    services.valheim = {
+      enable = true;
+      serverName = cfg.serverName;
+      worldName = cfg.worldName;
+      port = cfg.port;
+      crossplay = cfg.crossplay;
+      openFirewall = cfg.openFirewall;
+      passwordFile = config.secrets.valheim-password.dest;
+    };
+
+    # Configure Cloudflare DNS (no proxy for UDP game traffic)
+    nmasur.presets.services.cloudflare.noProxyDomains = [ hostnames.valheim ];
+
+  };
+
+}

platforms/nixos/modules/nmasur/profiles/communications.nix

@@ -61,6 +61,7 @@ in
         stalwart.enable = lib.mkDefault true;
         thelounge.enable = lib.mkDefault true;
         uptime-kuma.enable = lib.mkDefault true;
+        valheim.enable = lib.mkDefault false;
         vaultwarden.enable = lib.mkDefault true;
         victoriametrics.enable = lib.mkDefault true;
       };