extract borderVm config into separate file

bordervm-configuration.nix

@@ -0,0 +1,69 @@
+{ config, pkgs, ... }:
+{
+  imports = [
+    <nixpkgs/nixos/modules/virtualisation/qemu-vm.nix>
+  ];
+  boot.kernelParams = [
+    "loglevel=9"
+  ];
+  systemd.services.pppoe =
+    let conf = pkgs.writeText "kpppoed.toml"
+    ''
+      interface_name = "eth0"
+      services = [ "myservice" ]
+      lns_ipaddr = "90.155.53.19"
+      ac_name = "kpppoed-1.0"
+    '';
+    in  {
+      wantedBy = [ "multi-user.target" ];
+      serviceConfig = {
+        ExecStart = "${pkgs.go-l2tp}/bin/kpppoed -config ${conf}";
+      };
+    };
+  systemd.services.tufted = {
+    wantedBy = [ "multi-user.target" ];
+    serviceConfig = {
+      ExecStart = "${pkgs.tufted}/bin/tufted /home/liminix/liminix";
+    };
+  };
+  systemd.services.sshd.wantedBy = pkgs.lib.mkForce [ "multi-user.target" ];
+
+  virtualisation = {
+    qemu = {
+      networkingOptions = [];
+      options = [
+        "-device vfio-pci,host=01:00.0"
+        "-nographic"
+        "-serial mon:stdio"
+      ];
+    };
+    sharedDirectories = {
+      liminix = {
+        source = builtins.toString ./.;
+        target = "/home/liminix/liminix";
+      };
+    };
+  };
+  environment.systemPackages = with pkgs; [
+    tcpdump
+    wireshark
+    socat
+    tufted
+    iptables
+  ];
+  security.sudo.wheelNeedsPassword = false;
+  networking = {
+    hostName = "border";
+    firewall = { enable = false; };
+    interfaces.eth1 = {
+      useDHCP = false;
+      ipv4.addresses = [ { address = "10.0.0.1"; prefixLength = 24;}];
+    };
+  };
+  users.users.liminix = {
+    isNormalUser = true;
+    uid = 1000;
+    extraGroups = [ "wheel"];
+  };
+  services.getty.autologinUser = "liminix";
+}

default.nix

@@ -20,75 +20,12 @@ let
     ./modules/outputs.nix
   ] pkgs;
 
-  borderVm = ((import <nixpkgs/nixos>) {
-    configuration =
-      { config, ... }:
-      {
-        imports = [
-          <nixpkgs/nixos/modules/virtualisation/qemu-vm.nix>
-        ];
-        boot.kernelParams = [
-          "loglevel=9"
-        ];
-        systemd.services.pppoe =
-          let conf = pkgs.writeText "kpppoed.toml"
-            ''
-            interface_name = "eth0"
-            services = [ "myservice" ]
-            lns_ipaddr = "90.155.53.19"
-            ac_name = "kpppoed-1.0"
-            '';
-          in  {
-            wantedBy = [ "multi-user.target" ];
-            serviceConfig = {
-              ExecStart = "${pkgs.pkgsBuildBuild.go-l2tp}/bin/kpppoed -config ${conf}";
-            };
-          };
-        systemd.services.tufted = {
-            wantedBy = [ "multi-user.target" ];
-            serviceConfig = {
-              ExecStart = "${pkgs.pkgsBuildBuild.tufted}/bin/tufted /home/liminix/liminix";
-            };
-          };
-        virtualisation = {
-          qemu = {
-            networkingOptions = [];
-            options = [
-              "-device vfio-pci,host=01:00.0"
-              "-nographic"
-              "-serial mon:stdio"
-            ];
-          };
-          sharedDirectories = {
-            liminix = {
-              source = builtins.toString ./.;
-              target = "/home/liminix/liminix";
-            };
-          };
-        };
-        environment.systemPackages = with pkgs.pkgsBuildBuild; [
-          tcpdump
-          wireshark
-          socat
-          tufted
-          iptables
-        ];
-        security.sudo.wheelNeedsPassword = false;
-        networking = {
-          hostName = "border";
-          firewall = { enable = false; };
-          interfaces.eth1 = {
-            useDHCP = false;
-            ipv4.addresses = [ { address = "10.0.0.1"; prefixLength = 24;}];
-          };
-        };
-        users.users.liminix = {
-          isNormalUser = true;
-          uid = 1000;
-          extraGroups = [ "wheel"];
-        };
-        services.getty.autologinUser = "liminix";
-      };
+  borderVm = ((import <nixpkgs/nixos/lib/eval-config.nix>) {
+    system = builtins.currentSystem;
+    modules = [
+      ({  ... } : { nixpkgs.overlays = [ overlay ]; })
+      (import ./bordervm-configuration.nix)
+    ];
   }).config.system;
 in {
   outputs = config.outputs // {