add tailscale

systems/common.nix

@@ -1,6 +1,7 @@
 {
   lib,
   pkgs,
+  config,
   nixpkgs,
   ...
 }: {
@@ -16,6 +17,10 @@
     };
   };
 
+  age.secrets = {
+    tailscaleKey.file = ../secrets/tailscaleKey.age;
+  };
+
   programs = {
     ssh.startAgent = true;
 
@@ -33,6 +38,13 @@
       enable = true;
       openFirewall = lib.mkDefault false;
     };
+
+    tailscale = {
+      enable = true;
+      useRoutingFeatures = "both";
+      extraUpFlags = ["--ssh"];
+      authKeyFile = config.age.secrets.tailscaleKey.path;
+    };
   };
 
   nixpkgs.config.allowUnfree = true;