feat: IPv6 (#192)

* feat: custom ipv6 routes for all hosts
* fix: ipv6 - k3s+cilium

hosts/idols-ruby/default.nix

@@ -10,6 +10,10 @@
 #############################################################
 let
   hostName = "ruby"; # Define your hostname.
+
+  inherit (myvars.networking) defaultGateway defaultGateway6 nameservers;
+  inherit (myvars.networking.hostsAddr.${hostName}) iface ipv4;
+  ipv4WithMask = "${ipv4}/24";
 in {
   imports = mylib.scanPaths ./.;
 
@@ -32,9 +36,36 @@ in {
 
   networking = {
     inherit hostName;
-    inherit (myvars.networking) defaultGateway nameservers;
-    inherit (myvars.networking.hostsInterface.${hostName}) interfaces;
+
+    # we use networkd instead
     networkmanager.enable = false;
+    useDHCP = false;
+  };
+
+  networking.useNetworkd = true;
+  systemd.network.enable = true;
+
+  systemd.network.networks."10-${iface}" = {
+    matchConfig.Name = [iface];
+    networkConfig = {
+      Address = [ipv4WithMask];
+      DNS = nameservers;
+      DHCP = "ipv6"; # enable DHCPv6 only, so we can get a GUA.
+      IPv6AcceptRA = true; # for Stateless IPv6 Autoconfiguraton (SLAAC)
+      LinkLocalAddressing = "ipv6";
+    };
+    routes = [
+      {
+        Destination = "0.0.0.0/0";
+        Gateway = defaultGateway;
+      }
+      {
+        Destination = "::/0";
+        Gateway = defaultGateway6;
+        GatewayOnLink = true; # it's a gateway on local link.
+      }
+    ];
+    linkConfig.RequiredForOnline = "routable";
   };
 
   # This value determines the NixOS release from which the default