hosts/plover: move into systemd-networkd for network setup

hosts/plover/modules/hardware/hetzner-cloud-cx21.nix

@@ -3,6 +3,11 @@
 # Most of the filesystems listed here are supposed to be overriden to default
 # settings of whatever image format configuration this host system will import
 # from nixos-generators.
+let
+  network = import ./networks.nix;
+  inherit (network) publicIP publicIPv6 privateNetworkGatewayIP;
+in
+
 {
   imports = [
     (modulesPath + "/profiles/qemu-guest.nix")
@@ -33,15 +38,48 @@
 
   networking = {
     useDHCP = false;
-    enableIPv6 = true;
+    useNetworkd = true;
 
-    dhcpcd.persistent = true;
+    # We're using networkd to configure so we're disabling this
+    # service.
+    dhcpcd.enable = false;
+  };
 
-    interfaces = {
-      ens3 = {
-        useDHCP = true;
-      };
-      ens10.useDHCP = true;
+  # The interface configuration is based from the following discussion:
+  # https://discourse.nixos.org/t/nixos-on-hetzner-cloud-servers-ipv6/221/
+  systemd.network = {
+    enable = true;
+    networks."20-wan" = {
+      matchConfig.Name = "ens3";
+
+      address = [
+        # Public IPs.
+        publicIP
+        "${publicIPv6}1/64"
+
+        # The private network IP.
+        "172.23.0.1/32"
+
+        # Randomly generate from the IPv6 range.
+        "::"
+      ];
+
+      routes = [
+        # Configuring the route with the gateway addresses for this network.
+        { routeConfig.Gateway = "fe80::1"; }
+        { routeConfig.Destination = privateNetworkGatewayIP; }
+        { routeConfig = { Gateway = privateNetworkGatewayIP; GatewayOnLink = true; }; }
+
+        # Private addresses.
+        { routeConfig = { Destination = "172.16.0.0/12"; Type = "unreachable"; }; }
+        { routeConfig = { Destination = "192.168.0.0/16"; Type = "unreachable"; }; }
+        { routeConfig = { Destination = "10.0.0.0/8"; Type = "unreachable"; }; }
+        { routeConfig = { Destination = "fc00::/7"; Type = "unreachable"; }; }
+      ];
     };
   };
+
+  # This is to look out for any errors that will occur for my networking setup
+  # which is always a possibility.
+  systemd.services.systemd-networkd.serviceConfig.Environment = "SYSTEMD_LOG_LEVEL=debug";
 }

hosts/plover/modules/hardware/networks.nix

@@ -0,0 +1,10 @@
+# It just contains a set of network-related variables mainly used for
+# network-related services. Make sure to change this every time you migrate to
+# a new server.
+{
+  publicIP = "95.217.212.19/32";
+  publicIPv6 = "2a01:4f9:c011:a448::";
+
+  privateIPNetworkRange = "172.16.0.0/32";
+  privateNetworkGatewayIP = "172.16.0.1/32";
+}