sync CNI config in goroutine

pkg/kubelet/dockershim/network/cni/BUILD

@@ -20,6 +20,7 @@ go_library(
         "//pkg/kubelet/container:go_default_library",
         "//pkg/kubelet/dockershim/network:go_default_library",
         "//pkg/util/bandwidth:go_default_library",
+        "//staging/src/k8s.io/apimachinery/pkg/util/wait:go_default_library",
         "//vendor/github.com/containernetworking/cni/libcni:go_default_library",
         "//vendor/github.com/containernetworking/cni/pkg/types:go_default_library",
         "//vendor/k8s.io/klog:go_default_library",

pkg/kubelet/dockershim/network/cni/cni.go

@@ -24,9 +24,11 @@ import (
 	"sort"
 	"strings"
 	"sync"
+	"time"
 
 	"github.com/containernetworking/cni/libcni"
 	cnitypes "github.com/containernetworking/cni/pkg/types"
+	"k8s.io/apimachinery/pkg/util/wait"
 	"k8s.io/klog"
 	kubeletconfig "k8s.io/kubernetes/pkg/kubelet/apis/config"
 	runtimeapi "k8s.io/kubernetes/pkg/kubelet/apis/cri/runtime/v1alpha2"
@@ -38,6 +40,10 @@ import (
 
 const (
 	CNIPluginName = "cni"
+
+	// defaultSyncConfigPeriod is the default period to sync CNI config
+	// TODO: consider making this value configurable or to be a more appropriate value.
+	defaultSyncConfigPeriod = time.Second * 5
 )
 
 type cniNetworkPlugin struct {
@@ -194,6 +200,10 @@ func (plugin *cniNetworkPlugin) Init(host network.Host, hairpinMode kubeletconfi
 	plugin.host = host
 
 	plugin.syncNetworkConfig()
+
+	// start a goroutine to sync network config from confDir periodically to detect network config updates in every 5 seconds
+	go wait.Forever(plugin.syncNetworkConfig, defaultSyncConfigPeriod)
+
 	return nil
 }
 
@@ -264,9 +274,6 @@ func (plugin *cniNetworkPlugin) Name() string {
 }
 
 func (plugin *cniNetworkPlugin) Status() error {
-	// sync network config from confDir periodically to detect network config updates
-	plugin.syncNetworkConfig()
-
 	// Can't set up pods if we don't have any CNI network configs yet
 	return plugin.checkInitialized()
 }