[microvm] setup network, allow adding bridge interface to host

machines/configuration.nix

@@ -62,6 +62,31 @@ in
     specialArgs.inputs = inputs;
     modules = defaultMicroVMModules ++ [
       ./durruti/configuration.nix
+
+      {
+        microvm = {
+          interfaces = [
+            {
+              type = "tap";
+              id = "vm-test1";
+              mac = "02:00:00:00:00:01";
+            }
+          ];
+        };
+        
+        systemd.network.enable = true;
+        
+        systemd.network.networks."20-lan" = {
+          matchConfig.Type = "ether";
+          networkConfig = {
+            Address = ["10.0.0.3/24" "2001:db8::b/64"];
+            Gateway = "10.0.0.1";
+            DNS = ["1.1.1.1"];
+            IPv6AcceptRA = true;
+            DHCP = "no";
+          };
+        };
+      }
     ];
   };
 

machines/durruti/host_config.nix

@@ -19,6 +19,14 @@ in
         default = "";
         description = lib.mdDoc "ip of nix container provided for malo"; 
       };
+
+      microvm = {
+        enableHostBridge = mkOption {
+          default = false;
+          type = types.bool;
+          description = lib.mdDoc "Setup bridge device for microvms.";
+        };
+      };
     };
   };
 
@@ -45,5 +53,35 @@ in
       locations."/".proxyPass = "http://${cfg.host_ip}:80";
     };
 
+    systemd.network = mkIf cfg.microvm.enableHostBridge {
+      enable = true;
+      # create a bride device that all the microvms will be connected to
+      netdevs."10-microvm".netdevConfig = {
+        Kind = "bridge";
+        Name = "microvm";
+      };
+
+      networks."10-microvm" = {
+        matchConfig.Name = "microvm";
+        networkConfig = {
+          DHCPServer = true;
+          IPv6SendRA = true;
+        };
+        addresses = [ {
+          Address = "10.0.0.1/24";
+        } {
+          Address = "fd12:3456:789a::1/64";
+        } ];
+        ipv6Prefixes = [ {
+          Prefix = "fd12:3456:789a::/64";
+        } ];
+      };
+
+      # connect the vms to the bridge
+      networks."11-microvm" = {
+        matchConfig.Name = "vm-*";
+        networkConfig.Bridge = "microvm";
+      };
+    };
   };
 }