periodically reload the cni plugin config

Signed-off-by: Mike Danese <mikedanese@google.com>

pkg/kubelet/network/cni/cni.go

@@ -17,8 +17,11 @@ limitations under the License.
 package cni
 
 import (
+	"errors"
 	"fmt"
 	"sort"
+	"sync"
+	"time"
 
 	"github.com/appc/cni/libcni"
 	cnitypes "github.com/appc/cni/pkg/types"
@@ -27,6 +30,7 @@ import (
 	kubecontainer "k8s.io/kubernetes/pkg/kubelet/container"
 	"k8s.io/kubernetes/pkg/kubelet/network"
 	utilexec "k8s.io/kubernetes/pkg/util/exec"
+	"k8s.io/kubernetes/pkg/util/wait"
 )
 
 const (
@@ -40,7 +44,10 @@ type cniNetworkPlugin struct {
 	network.NoopNetworkPlugin
 
 	loNetwork *cniNetwork
+
+	sync.RWMutex
 	defaultNetwork *cniNetwork
+
 	host        network.Host
 	execer      utilexec.Interface
 	nsenterPath string
@@ -53,16 +60,19 @@ type cniNetwork struct {
 }
 
 func probeNetworkPluginsWithVendorCNIDirPrefix(pluginDir, vendorCNIDirPrefix string) []network.NetworkPlugin {
-	configList := make([]network.NetworkPlugin, 0)
-	network, err := getDefaultCNINetwork(pluginDir, vendorCNIDirPrefix)
-	if err != nil {
-		return configList
-	}
-	return append(configList, &cniNetworkPlugin{
-		defaultNetwork: network,
+	plugin := &cniNetworkPlugin{
+		defaultNetwork: nil,
 		loNetwork:      getLoNetwork(vendorCNIDirPrefix),
 		execer:         utilexec.New(),
-	})
+	}
+
+	plugin.syncNetworkConfig(pluginDir, vendorCNIDirPrefix)
+	// sync network config from pluginDir periodically to detect network config updates
+	go wait.Forever(func() {
+		plugin.syncNetworkConfig(pluginDir, vendorCNIDirPrefix)
+	}, 10*time.Second)
+
+	return []network.NetworkPlugin{plugin}
 }
 
 func ProbeNetworkPlugins(pluginDir string) []network.NetworkPlugin {
@@ -137,11 +147,42 @@ func (plugin *cniNetworkPlugin) Init(host network.Host, hairpinMode componentcon
 	return nil
 }
 
+func (plugin *cniNetworkPlugin) syncNetworkConfig(pluginDir, vendorCNIDirPrefix string) {
+	network, err := getDefaultCNINetwork(pluginDir, vendorCNIDirPrefix)
+	if err != nil {
+		glog.Errorf("error updating cni config: %s", err)
+		return
+	}
+	plugin.setDefaultNetwork(network)
+}
+
+func (plugin *cniNetworkPlugin) getDefaultNetwork() *cniNetwork {
+	plugin.RLock()
+	defer plugin.RUnlock()
+	return plugin.defaultNetwork
+}
+
+func (plugin *cniNetworkPlugin) setDefaultNetwork(n *cniNetwork) {
+	plugin.Lock()
+	defer plugin.Unlock()
+	plugin.defaultNetwork = n
+}
+
+func (plugin *cniNetworkPlugin) checkInitialized() error {
+	if plugin.getDefaultNetwork() == nil {
+		return errors.New("cni config unintialized")
+	}
+	return nil
+}
+
 func (plugin *cniNetworkPlugin) Name() string {
 	return CNIPluginName
 }
 
 func (plugin *cniNetworkPlugin) SetUpPod(namespace string, name string, id kubecontainer.ContainerID) error {
+	if err := plugin.checkInitialized(); err != nil {
+		return err
+	}
 	netnsPath, err := plugin.host.GetRuntime().GetNetNS(id)
 	if err != nil {
 		return fmt.Errorf("CNI failed to retrieve network namespace path: %v", err)
@@ -153,7 +194,7 @@ func (plugin *cniNetworkPlugin) SetUpPod(namespace string, name string, id kubec
 		return err
 	}
 
-	_, err = plugin.defaultNetwork.addToNetwork(name, namespace, id, netnsPath)
+	_, err = plugin.getDefaultNetwork().addToNetwork(name, namespace, id, netnsPath)
 	if err != nil {
 		glog.Errorf("Error while adding to cni network: %s", err)
 		return err
@@ -163,12 +204,15 @@ func (plugin *cniNetworkPlugin) SetUpPod(namespace string, name string, id kubec
 }
 
 func (plugin *cniNetworkPlugin) TearDownPod(namespace string, name string, id kubecontainer.ContainerID) error {
+	if err := plugin.checkInitialized(); err != nil {
+		return err
+	}
 	netnsPath, err := plugin.host.GetRuntime().GetNetNS(id)
 	if err != nil {
 		return fmt.Errorf("CNI failed to retrieve network namespace path: %v", err)
 	}
 
-	return plugin.defaultNetwork.deleteFromNetwork(name, namespace, id, netnsPath)
+	return plugin.getDefaultNetwork().deleteFromNetwork(name, namespace, id, netnsPath)
 }
 
 // TODO: Use the addToNetwork function to obtain the IP of the Pod. That will assume idempotent ADD call to the plugin.