feat: initial commit, migrate main config from dot013/.nix

modules/tailscale.nix

@@ -0,0 +1,62 @@
+{ config
+, lib
+, ...
+}:
+let
+  cfg = config.services.tailscale;
+in
+{
+  imports = [ ];
+  options.services.tailscale = with lib;
+    with lib.types; {
+      exitNode = mkOption {
+        type = bool;
+        default = false;
+      };
+      tailnetName = mkOption {
+        type = str;
+      };
+      tailnetUrl = mkOption {
+        type = str;
+        default = "${config.services.tailscale.tailnetName}.ts.net";
+      };
+      deviceUrl = mkOption {
+        type = str;
+        default = "${config.networking.hostName}.${config.services.tailscale.tailnetUrl}";
+      };
+      deviceIp = mkOption {
+        type = str;
+      };
+    };
+  config = with lib;
+    mkIf cfg.enable {
+      services.tailscale = {
+        extraUpFlags = [
+          (
+            if cfg.exitNode
+            then "--advertise-exit-node"
+            else null
+          )
+          (
+            if cfg.exitNode
+            then "--exit-node"
+            else null
+          )
+        ];
+        useRoutingFeatures = mkDefault (
+          if cfg.exitNode
+          then "server"
+          else "client"
+        );
+      };
+
+      systemd.services."tailscaled" = mkIf config.services.caddy.enable (mkDefault {
+        serviceConfig = {
+          Environment = [ "TS_PERMIT_CERT_UID=caddy" ];
+        };
+      });
+
+      boot.kernel.sysctl."net.ipv4.ip_forward" = mkIf cfg.exitNode (mkDefault 1);
+      boot.kernel.sysctl."net.ipv6.conf.all.forwarding" = mkIf cfg.exitNode (mkDefault 1);
+    };
+}