enable dual CNI plugin dataplanes

cni-plugin/pkg/dataplane/dataplane.go

@@ -50,10 +50,28 @@ func GetDataplane(conf types.NetConf, logger *logrus.Entry) (Dataplane, error) {
 	if !ok {
 		return getDefaultSystemDataplane(conf, logger)
 	}
+
+	var externalDataplane Dataplane
+
 	switch name {
 	case "grpc":
-		return grpc.NewGrpcDataplane(conf, logger)
+		var err error
+		externalDataplane, err = grpc.NewGrpcDataplane(conf, logger)
+		if err != nil {
+			return nil, fmt.Errorf("Unable to create a new GRPC dataplane: %w", err)
+		}
 	default:
 		return nil, fmt.Errorf("Invalid dataplane type: %s", name)
 	}
+
+	useAsSecondary, ok := conf.DataplaneOptions["useAsSecondary"]
+	if useAsSecondary == "true" {
+		defaultSystemDataplane, err := getDefaultSystemDataplane(conf, logger)
+		if err != nil {
+			return nil, fmt.Errorf("Unable to create new GRPC dataplane: %w", err)
+		}
+		return multiplexer{primary: defaultSystemDataplane, secondary: externalDataplane}, nil
+	}
+
+	return externalDataplane, nil
 }

cni-plugin/pkg/dataplane/multiplexer.go

@@ -0,0 +1,64 @@
+// Copyright (c) 2025 NeuReality Ltd.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package dataplane
+
+import (
+	"context"
+	"fmt"
+	"net"
+
+	"github.com/containernetworking/cni/pkg/skel"
+	cniv1 "github.com/containernetworking/cni/pkg/types/100"
+	api "github.com/projectcalico/calico/libcalico-go/lib/apis/v3"
+	calicoclient "github.com/projectcalico/calico/libcalico-go/lib/clientv3"
+)
+
+type multiplexer struct {
+	primary   Dataplane
+	secondary Dataplane
+}
+
+func (m multiplexer) DoNetworking(
+	ctx context.Context,
+	calicoClient calicoclient.Interface,
+	args *skel.CmdArgs,
+	result *cniv1.Result,
+	desiredVethName string,
+	routes []*net.IPNet,
+	endpoint *api.WorkloadEndpoint,
+	annotations map[string]string,
+) (string, string, error) {
+	_, _, secondaryErr := m.secondary.DoNetworking(ctx, calicoClient, args, result, desiredVethName, routes, endpoint, annotations)
+	hostVethName, contVethMAC, primaryErr := m.primary.DoNetworking(ctx, calicoClient, args, result, desiredVethName, routes, endpoint, annotations)
+
+	if primaryErr != nil || secondaryErr != nil {
+		return "", "", fmt.Errorf("errors in sending message to dataplanes: primary error %w, secondary error %w",
+			primaryErr, secondaryErr)
+	}
+
+	return hostVethName, contVethMAC, nil
+}
+
+func (m multiplexer) CleanUpNamespace(args *skel.CmdArgs) error {
+	secondaryErr := m.secondary.CleanUpNamespace(args)
+	primaryErr := m.primary.CleanUpNamespace(args)
+
+	if primaryErr != nil || secondaryErr != nil {
+		return fmt.Errorf("errors in clean up namespaces of dataplanes: primary error %w, secondary error %w",
+			primaryErr, secondaryErr)
+	}
+
+	return nil
+}