multus-cni/pkg/k8sclient/k8sclient.go

// Copyright (c) 2017 Intel Corporation
//
// 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 k8sclient

import (
	"context"
	"encoding/json"
	"fmt"
	"net"
	"os"
	"regexp"
	"strings"
	"time"

	v1 "k8s.io/api/core/v1"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/runtime"
	"k8s.io/client-go/kubernetes"
	"k8s.io/client-go/kubernetes/scheme"
	v1core "k8s.io/client-go/kubernetes/typed/core/v1"
	"k8s.io/client-go/rest"
	"k8s.io/client-go/tools/clientcmd"
	"k8s.io/client-go/tools/record"
	"k8s.io/klog"

	"github.com/containernetworking/cni/libcni"
	"github.com/containernetworking/cni/pkg/skel"
	cnitypes "github.com/containernetworking/cni/pkg/types"
	nettypes "github.com/k8snetworkplumbingwg/network-attachment-definition-client/pkg/apis/k8s.cni.cncf.io/v1"
	netclient "github.com/k8snetworkplumbingwg/network-attachment-definition-client/pkg/client/clientset/versioned/typed/k8s.cni.cncf.io/v1"
	netutils "github.com/k8snetworkplumbingwg/network-attachment-definition-client/pkg/utils"
	"gopkg.in/k8snetworkplumbingwg/multus-cni.v3/pkg/kubeletclient"
	"gopkg.in/k8snetworkplumbingwg/multus-cni.v3/pkg/logging"
	"gopkg.in/k8snetworkplumbingwg/multus-cni.v3/pkg/types"
)

const (
	resourceNameAnnot      = "k8s.v1.cni.cncf.io/resourceName"
	defaultNetAnnot        = "v1.multus-cni.io/default-network"
	networkAttachmentAnnot = "k8s.v1.cni.cncf.io/networks"
)

// NoK8sNetworkError indicates error, no network in kubernetes
type NoK8sNetworkError struct {
	message string
}

// ClientInfo contains information given from k8s client
type ClientInfo struct {
	Client           kubernetes.Interface
	NetClient        netclient.K8sCniCncfIoV1Interface
	EventBroadcaster record.EventBroadcaster
	EventRecorder    record.EventRecorder
}

// AddPod adds pod into kubernetes
func (c *ClientInfo) AddPod(pod *v1.Pod) (*v1.Pod, error) {
	return c.Client.CoreV1().Pods(pod.ObjectMeta.Namespace).Create(context.TODO(), pod, metav1.CreateOptions{})
}

// GetPod gets pod from kubernetes
func (c *ClientInfo) GetPod(namespace, name string) (*v1.Pod, error) {
	return c.Client.CoreV1().Pods(namespace).Get(context.TODO(), name, metav1.GetOptions{})
}

// DeletePod deletes a pod from kubernetes
func (c *ClientInfo) DeletePod(namespace, name string) error {
	return c.Client.CoreV1().Pods(namespace).Delete(context.TODO(), name, metav1.DeleteOptions{})
}

// AddNetAttachDef adds net-attach-def into kubernetes
func (c *ClientInfo) AddNetAttachDef(netattach *nettypes.NetworkAttachmentDefinition) (*nettypes.NetworkAttachmentDefinition, error) {
	return c.NetClient.NetworkAttachmentDefinitions(netattach.ObjectMeta.Namespace).Create(context.TODO(), netattach, metav1.CreateOptions{})
}

// Eventf puts event into kubernetes events
func (c *ClientInfo) Eventf(object runtime.Object, eventtype, reason, messageFmt string, args ...interface{}) {
	if c != nil && c.EventRecorder != nil {
		c.EventRecorder.Eventf(object, eventtype, reason, messageFmt, args...)
	}
}

func (e *NoK8sNetworkError) Error() string { return string(e.message) }

// SetNetworkStatus sets network status into Pod annotation
func SetNetworkStatus(client *ClientInfo, k8sArgs *types.K8sArgs, netStatus []nettypes.NetworkStatus, conf *types.NetConf) error {
	var err error
	logging.Debugf("SetNetworkStatus: %v, %v, %v, %v", client, k8sArgs, netStatus, conf)

	client, err = GetK8sClient(conf.Kubeconfig, client)
	if err != nil {
		return logging.Errorf("SetNetworkStatus: %v", err)
	}
	if client == nil || client.Client == nil {
		if len(conf.Delegates) == 0 {
			// No available kube client and no delegates, we can't do anything
			return logging.Errorf("SetNetworkStatus: must have either Kubernetes config or delegates")
		}
		logging.Debugf("SetNetworkStatus: kube client info is not defined, skip network status setup")
		return nil
	}

	podName := string(k8sArgs.K8S_POD_NAME)
	podNamespace := string(k8sArgs.K8S_POD_NAMESPACE)
	podUID := string(k8sArgs.K8S_POD_UID)
	pod, err := client.GetPod(podNamespace, podName)
	if err != nil {
		return logging.Errorf("SetNetworkStatus: failed to query the pod %v in out of cluster comm: %v", podName, err)
	}

	if podUID != "" && string(pod.UID) != podUID {
		return logging.Errorf("SetNetworkStatus: expected pod %s/%s UID %q but got %q from Kube API", podNamespace, podName, podUID, pod.UID)
	}

	if netStatus != nil {
		err = netutils.SetNetworkStatus(client.Client, pod, netStatus)
		if err != nil {
			return logging.Errorf("SetNetworkStatus: failed to update the pod %v in out of cluster comm: %v", podName, err)
		}
	}

	return nil
}

func parsePodNetworkObjectName(podnetwork string) (string, string, string, error) {
	var netNsName string
	var netIfName string
	var networkName string

	logging.Debugf("parsePodNetworkObjectName: %s", podnetwork)
	slashItems := strings.Split(podnetwork, "/")
	if len(slashItems) == 2 {
		netNsName = strings.TrimSpace(slashItems[0])
		networkName = slashItems[1]
	} else if len(slashItems) == 1 {
		networkName = slashItems[0]
	} else {
		return "", "", "", logging.Errorf("parsePodNetworkObjectName: Invalid network object (failed at '/')")
	}

	atItems := strings.Split(networkName, "@")
	networkName = strings.TrimSpace(atItems[0])
	if len(atItems) == 2 {
		netIfName = strings.TrimSpace(atItems[1])
	} else if len(atItems) != 1 {
		return "", "", "", logging.Errorf("parsePodNetworkObjectName: Invalid network object (failed at '@')")
	}

	// Check and see if each item matches the specification for valid attachment name.
	// "Valid attachment names must be comprised of units of the DNS-1123 label format"
	// [a-z0-9]([-a-z0-9]*[a-z0-9])?
	// And we allow at (@), and forward slash (/) (units separated by commas)
	// It must start and end alphanumerically.
	allItems := []string{netNsName, networkName, netIfName}
	for i := range allItems {
		matched, _ := regexp.MatchString("^[a-z0-9]([-a-z0-9]*[a-z0-9])?$", allItems[i])
		if !matched && len([]rune(allItems[i])) > 0 {
			return "", "", "", logging.Errorf(fmt.Sprintf("parsePodNetworkObjectName: Failed to parse: one or more items did not match comma-delimited format (must consist of lower case alphanumeric characters). Must start and end with an alphanumeric character), mismatch @ '%v'", allItems[i]))
		}
	}

	logging.Debugf("parsePodNetworkObjectName: parsed: %s, %s, %s", netNsName, networkName, netIfName)
	return netNsName, networkName, netIfName, nil
}

func parsePodNetworkAnnotation(podNetworks, defaultNamespace string) ([]*types.NetworkSelectionElement, error) {
	var networks []*types.NetworkSelectionElement

	logging.Debugf("parsePodNetworkAnnotation: %s, %s", podNetworks, defaultNamespace)
	if podNetworks == "" {
		return nil, logging.Errorf("parsePodNetworkAnnotation: pod annotation does not have \"network\" as key")
	}

	if strings.IndexAny(podNetworks, "[{\"") >= 0 {
		if err := json.Unmarshal([]byte(podNetworks), &networks); err != nil {
			return nil, logging.Errorf("parsePodNetworkAnnotation: failed to parse pod Network Attachment Selection Annotation JSON format: %v", err)
		}
	} else {
		// Comma-delimited list of network attachment object names
		for _, item := range strings.Split(podNetworks, ",") {
			// Remove leading and trailing whitespace.
			item = strings.TrimSpace(item)

			// Parse network name (i.e. <namespace>/<network name>@<ifname>)
			netNsName, networkName, netIfName, err := parsePodNetworkObjectName(item)
			if err != nil {
				return nil, logging.Errorf("parsePodNetworkAnnotation: %v", err)
			}

			networks = append(networks, &types.NetworkSelectionElement{
				Name:             networkName,
				Namespace:        netNsName,
				InterfaceRequest: netIfName,
			})
		}
	}

	for _, n := range networks {
		if n.Namespace == "" {
			n.Namespace = defaultNamespace
		}
		if n.MacRequest != "" {
			// validate MAC address
			if _, err := net.ParseMAC(n.MacRequest); err != nil {
				return nil, logging.Errorf("parsePodNetworkAnnotation: failed to mac: %v", err)
			}
		}
		if n.InfinibandGUIDRequest != "" {
			// validate GUID address
			if _, err := net.ParseMAC(n.InfinibandGUIDRequest); err != nil {
				return nil, logging.Errorf("parsePodNetworkAnnotation: failed to validate infiniband GUID: %v", err)
			}
		}
		if n.IPRequest != nil {
			for _, ip := range n.IPRequest {
				// validate IP address
				if strings.Contains(ip, "/") {
					if _, _, err := net.ParseCIDR(ip); err != nil {
						return nil, logging.Errorf("failed to parse CIDR %q: %v", ip, err)
					}
				} else if net.ParseIP(ip) == nil {
					return nil, logging.Errorf("failed to parse IP address %q", ip)
				}
			}
		}
		// compatibility pre v3.2, will be removed in v4.0
		if n.DeprecatedInterfaceRequest != "" && n.InterfaceRequest == "" {
			n.InterfaceRequest = n.DeprecatedInterfaceRequest
		}
	}

	return networks, nil
}

func getKubernetesDelegate(client *ClientInfo, net *types.NetworkSelectionElement, confdir string, pod *v1.Pod, resourceMap map[string]*types.ResourceInfo) (*types.DelegateNetConf, map[string]*types.ResourceInfo, error) {

	logging.Debugf("getKubernetesDelegate: %v, %v, %s, %v, %v", client, net, confdir, pod, resourceMap)
	customResource, err := client.NetClient.NetworkAttachmentDefinitions(net.Namespace).Get(context.TODO(), net.Name, metav1.GetOptions{})
	if err != nil {
		errMsg := fmt.Sprintf("cannot find a network-attachment-definition (%s) in namespace (%s): %v", net.Name, net.Namespace, err)
		if client != nil {
			client.Eventf(pod, v1.EventTypeWarning, "NoNetworkFound", errMsg)
		}
		return nil, resourceMap, logging.Errorf("getKubernetesDelegate: " + errMsg)
	}

	// Get resourceName annotation from NetworkAttachmentDefinition
	deviceID := ""
	resourceName, ok := customResource.GetAnnotations()[resourceNameAnnot]
	if ok && pod.Name != "" && pod.Namespace != "" {
		// ResourceName annotation is found; try to get device info from resourceMap
		logging.Debugf("getKubernetesDelegate: found resourceName annotation : %s", resourceName)

		if resourceMap == nil {
			ck, err := kubeletclient.GetResourceClient("")
			if err != nil {
				return nil, resourceMap, logging.Errorf("getKubernetesDelegate: failed to get a ResourceClient instance: %v", err)
			}
			resourceMap, err = ck.GetPodResourceMap(pod)
			if err != nil {
				return nil, resourceMap, logging.Errorf("getKubernetesDelegate: failed to get resourceMap from ResourceClient: %v", err)
			}
			logging.Debugf("getKubernetesDelegate: resourceMap instance: %+v", resourceMap)
		}

		entry, ok := resourceMap[resourceName]
		if ok {
			if idCount := len(entry.DeviceIDs); idCount > 0 && idCount > entry.Index {
				deviceID = entry.DeviceIDs[entry.Index]
				logging.Debugf("getKubernetesDelegate: podName: %s deviceID: %s", pod.Name, deviceID)
				entry.Index++ // increment Index for next delegate
			}
		}
	}

	configBytes, err := netutils.GetCNIConfig(customResource, confdir)
	if err != nil {
		return nil, resourceMap, err
	}

	delegate, err := types.LoadDelegateNetConf(configBytes, net, deviceID, resourceName)
	if err != nil {
		return nil, resourceMap, err
	}

	return delegate, resourceMap, nil
}

// GetK8sArgs gets k8s related args from CNI args
func GetK8sArgs(args *skel.CmdArgs) (*types.K8sArgs, error) {
	k8sArgs := &types.K8sArgs{}

	logging.Debugf("GetK8sArgs: %v", args)
	err := cnitypes.LoadArgs(args.Args, k8sArgs)
	if err != nil {
		return nil, err
	}

	return k8sArgs, nil
}

// TryLoadPodDelegates attempts to load Kubernetes-defined delegates and add them to the Multus config.
// Returns the number of Kubernetes-defined delegates added or an error.
func TryLoadPodDelegates(pod *v1.Pod, conf *types.NetConf, clientInfo *ClientInfo, resourceMap map[string]*types.ResourceInfo) (int, *ClientInfo, error) {
	var err error

	logging.Debugf("TryLoadPodDelegates: %v, %v, %v", pod, conf, clientInfo)
	clientInfo, err = GetK8sClient(conf.Kubeconfig, clientInfo)
	if err != nil {
		return 0, nil, err
	}

	if clientInfo == nil {
		if len(conf.Delegates) == 0 {
			// No available kube client and no delegates, we can't do anything
			return 0, nil, logging.Errorf("TryLoadPodDelegates: must have either Kubernetes config or delegates")
		}
		return 0, nil, nil
	}

	delegate, err := tryLoadK8sPodDefaultNetwork(clientInfo, pod, conf)
	if err != nil {
		return 0, nil, logging.Errorf("TryLoadPodDelegates: error in loading K8s cluster default network from pod annotation: %v", err)
	}
	if delegate != nil {
		logging.Debugf("TryLoadPodDelegates: Overwrite the cluster default network with %v from pod annotations", delegate)

		conf.Delegates[0] = delegate
	}

	networks, err := GetPodNetwork(pod)
	if networks != nil {
		delegates, err := GetNetworkDelegates(clientInfo, pod, networks, conf, resourceMap)

		if err != nil {
			if _, ok := err.(*NoK8sNetworkError); ok {
				return 0, clientInfo, nil
			}
			return 0, nil, logging.Errorf("TryLoadPodDelegates: error in getting k8s network for pod: %v", err)
		}

		if err = conf.AddDelegates(delegates); err != nil {
			return 0, nil, err
		}

		// Check gatewayRequest is configured in delegates
		// and mark its config if gateway filter is required
		isGatewayConfigured := false
		for _, delegate := range conf.Delegates {
			if delegate.GatewayRequest != nil {
				isGatewayConfigured = true
				break
			}
		}

		if isGatewayConfigured == true {
			types.CheckGatewayConfig(conf.Delegates)
		}

		return len(delegates), clientInfo, nil
	}

	if _, ok := err.(*NoK8sNetworkError); ok {
		return 0, clientInfo, nil
	}
	return 0, clientInfo, err
}

// GetK8sClient gets client info from kubeconfig
func GetK8sClient(kubeconfig string, kubeClient *ClientInfo) (*ClientInfo, error) {
	logging.Debugf("GetK8sClient: %s, %v", kubeconfig, kubeClient)
	// If we get a valid kubeClient (eg from testcases) just return that
	// one.
	if kubeClient != nil {
		return kubeClient, nil
	}

	var err error
	var config *rest.Config

	// Otherwise try to create a kubeClient from a given kubeConfig
	if kubeconfig != "" {
		// uses the current context in kubeconfig
		config, err = clientcmd.BuildConfigFromFlags("", kubeconfig)
		if err != nil {
			return nil, logging.Errorf("GetK8sClient: failed to get context for the kubeconfig %v: %v", kubeconfig, err)
		}
	} else if os.Getenv("KUBERNETES_SERVICE_HOST") != "" && os.Getenv("KUBERNETES_SERVICE_PORT") != "" {
		// Try in-cluster config where multus might be running in a kubernetes pod
		config, err = rest.InClusterConfig()
		if err != nil {
			return nil, logging.Errorf("GetK8sClient: failed to get context for in-cluster kube config: %v", err)
		}
	} else {
		// No kubernetes config; assume we shouldn't talk to Kube at all
		return nil, nil
	}

	// Specify that we use gRPC
	config.AcceptContentTypes = "application/vnd.kubernetes.protobuf,application/json"
	config.ContentType = "application/vnd.kubernetes.protobuf"
	// Set the config timeout to one minute.
	config.Timeout = time.Minute

	// creates the clientset
	client, err := kubernetes.NewForConfig(config)
	if err != nil {
		return nil, err
	}

	netclient, err := netclient.NewForConfig(config)
	if err != nil {
		return nil, err
	}

	broadcaster := record.NewBroadcaster()
	broadcaster.StartLogging(klog.Infof)
	broadcaster.StartRecordingToSink(&v1core.EventSinkImpl{Interface: client.CoreV1().Events("")})
	recorder := broadcaster.NewRecorder(scheme.Scheme, v1.EventSource{Component: "multus"})

	return &ClientInfo{
		Client:           client,
		NetClient:        netclient,
		EventBroadcaster: broadcaster,
		EventRecorder:    recorder,
	}, nil
}

// GetPodNetwork gets net-attach-def annotation from pod
func GetPodNetwork(pod *v1.Pod) ([]*types.NetworkSelectionElement, error) {
	logging.Debugf("GetPodNetwork: %v", pod)

	netAnnot := pod.Annotations[networkAttachmentAnnot]
	defaultNamespace := pod.ObjectMeta.Namespace

	if len(netAnnot) == 0 {
		return nil, &NoK8sNetworkError{"no kubernetes network found"}
	}

	networks, err := parsePodNetworkAnnotation(netAnnot, defaultNamespace)
	if err != nil {
		return nil, err
	}
	return networks, nil
}

// GetNetworkDelegates returns delegatenetconf from net-attach-def annotation in pod
func GetNetworkDelegates(k8sclient *ClientInfo, pod *v1.Pod, networks []*types.NetworkSelectionElement, conf *types.NetConf, resourceMap map[string]*types.ResourceInfo) ([]*types.DelegateNetConf, error) {
	logging.Debugf("GetNetworkDelegates: %v, %v, %v, %v, %v", k8sclient, pod, networks, conf, resourceMap)

	// Read all network objects referenced by 'networks'
	var delegates []*types.DelegateNetConf
	defaultNamespace := pod.ObjectMeta.Namespace

	for _, net := range networks {

		// The pods namespace (stored as defaultNamespace, does not equal the annotation's target namespace in net.Namespace)
		// In the case that this is a mismatch when namespaceisolation is enabled, this should be an error.
		if conf.NamespaceIsolation {
			if defaultNamespace != net.Namespace {
				// We allow exceptions based on the specified list of non-isolated namespaces (and/or "default" namespace, by default)
				if !isValidNamespaceReference(net.Namespace, conf.NonIsolatedNamespaces) {
					return nil, logging.Errorf("GetNetworkDelegates: namespace isolation enabled, annotation violates permission, pod is in namespace %v but refers to target namespace %v", defaultNamespace, net.Namespace)
				}
			}
		}

		delegate, updatedResourceMap, err := getKubernetesDelegate(k8sclient, net, conf.ConfDir, pod, resourceMap)
		if err != nil {
			return nil, logging.Errorf("GetNetworkDelegates: failed getting the delegate: %v", err)
		}
		delegates = append(delegates, delegate)
		resourceMap = updatedResourceMap
	}

	return delegates, nil
}

func isValidNamespaceReference(targetns string, allowednamespaces []string) bool {
	for _, eachns := range allowednamespaces {
		if eachns == targetns {
			return true
		}
	}
	return false
}

func getNetDelegate(client *ClientInfo, pod *v1.Pod, netname, confdir, namespace string, resourceMap map[string]*types.ResourceInfo) (*types.DelegateNetConf, map[string]*types.ResourceInfo, error) {
	logging.Debugf("getNetDelegate: %v, %v, %v, %s", client, netname, confdir, namespace)
	// option1) search CRD object for the network
	net := &types.NetworkSelectionElement{
		Name:      netname,
		Namespace: namespace,
	}
	delegate, resourceMap, err := getKubernetesDelegate(client, net, confdir, pod, resourceMap)
	if err == nil {
		return delegate, resourceMap, nil
	}

	// option2) search CNI json config file
	var configBytes []byte
	configBytes, err = netutils.GetCNIConfigFromFile(netname, confdir)
	if err == nil {
		delegate, err := types.LoadDelegateNetConf(configBytes, nil, "", "")
		if err != nil {
			return nil, resourceMap, err
		}
		return delegate, resourceMap, nil
	}

	// option3) search directory
	fInfo, err := os.Stat(netname)
	if err == nil {
		if fInfo.IsDir() {
			files, err := libcni.ConfFiles(netname, []string{".conf", ".conflist"})
			if err != nil {
				return nil, resourceMap, err
			}
			if len(files) > 0 {
				var configBytes []byte
				configBytes, err = netutils.GetCNIConfigFromFile("", netname)
				if err == nil {
					delegate, err := types.LoadDelegateNetConf(configBytes, nil, "", "")
					if err != nil {
						return nil, resourceMap, err
					}
					return delegate, resourceMap, nil
				}
				return nil, resourceMap, err
			}
		}
	}
	return nil, resourceMap, logging.Errorf("getNetDelegate: cannot find network: %v", netname)
}

// GetDefaultNetworks parses 'defaultNetwork' config, gets network json and put it into netconf.Delegates.
func GetDefaultNetworks(pod *v1.Pod, conf *types.NetConf, kubeClient *ClientInfo, resourceMap map[string]*types.ResourceInfo) (map[string]*types.ResourceInfo, error) {
	logging.Debugf("GetDefaultNetworks: %v, %v, %v, %v", pod, conf, kubeClient, resourceMap)
	var delegates []*types.DelegateNetConf

	kubeClient, err := GetK8sClient(conf.Kubeconfig, kubeClient)
	if err != nil {
		return resourceMap, err
	}
	if kubeClient == nil {
		if len(conf.Delegates) == 0 {
			// No available kube client and no delegates, we can't do anything
			return resourceMap, logging.Errorf("GetDefaultNetworks: must have either Kubernetes config or delegates")
		}
		return resourceMap, nil
	}

	delegate, resourceMap, err := getNetDelegate(kubeClient, pod, conf.ClusterNetwork, conf.ConfDir, conf.MultusNamespace, resourceMap)

	if err != nil {
		return resourceMap, logging.Errorf("GetDefaultNetworks: failed to get clusterNetwork %s in namespace %s", conf.ClusterNetwork, conf.MultusNamespace)
	}
	delegate.MasterPlugin = true
	delegates = append(delegates, delegate)

	// Pod in kube-system namespace does not have default network for now.
	if !types.CheckSystemNamespaces(pod.ObjectMeta.Namespace, conf.SystemNamespaces) {
		for _, netname := range conf.DefaultNetworks {
			delegate, resourceMap, err := getNetDelegate(kubeClient, pod, netname, conf.ConfDir, conf.MultusNamespace, resourceMap)
			if err != nil {
				return resourceMap, err
			}
			delegates = append(delegates, delegate)
		}
	}

	if err = conf.AddDelegates(delegates); err != nil {
		return resourceMap, err
	}

	return resourceMap, nil
}

// tryLoadK8sPodDefaultNetwork get pod default network from annotations
func tryLoadK8sPodDefaultNetwork(kubeClient *ClientInfo, pod *v1.Pod, conf *types.NetConf) (*types.DelegateNetConf, error) {
	var netAnnot string
	logging.Debugf("tryLoadK8sPodDefaultNetwork: %v, %v, %v", kubeClient, pod, conf)

	netAnnot, ok := pod.Annotations[defaultNetAnnot]
	if !ok {
		logging.Debugf("tryLoadK8sPodDefaultNetwork: Pod default network annotation is not defined")
		return nil, nil
	}

	// The CRD object of default network should only be defined in multusNamespace
	networks, err := parsePodNetworkAnnotation(netAnnot, conf.MultusNamespace)
	if err != nil {
		return nil, logging.Errorf("tryLoadK8sPodDefaultNetwork: failed to parse CRD object: %v", err)
	}
	if len(networks) > 1 {
		return nil, logging.Errorf("tryLoadK8sPodDefaultNetwork: more than one default network is specified: %s", netAnnot)
	}

	delegate, _, err := getKubernetesDelegate(kubeClient, networks[0], conf.ConfDir, pod, nil)
	if err != nil {
		return nil, logging.Errorf("tryLoadK8sPodDefaultNetwork: failed getting the delegate: %v", err)
	}
	delegate.MasterPlugin = true

	return delegate, nil
}