Teach dockershim to probe for network plugins

pkg/kubelet/dockershim/docker_service.go

@@ -21,10 +21,14 @@ import (
 	"io"
 
 	"k8s.io/kubernetes/pkg/api"
+	"k8s.io/kubernetes/pkg/apis/componentconfig"
 	internalApi "k8s.io/kubernetes/pkg/kubelet/api"
 	runtimeApi "k8s.io/kubernetes/pkg/kubelet/api/v1alpha1/runtime"
 	kubecontainer "k8s.io/kubernetes/pkg/kubelet/container"
 	"k8s.io/kubernetes/pkg/kubelet/dockertools"
+	"k8s.io/kubernetes/pkg/kubelet/network"
+	"k8s.io/kubernetes/pkg/kubelet/network/cni"
+	"k8s.io/kubernetes/pkg/kubelet/network/kubenet"
 	"k8s.io/kubernetes/pkg/kubelet/server/streaming"
 	"k8s.io/kubernetes/pkg/util/term"
 )
@@ -53,10 +57,40 @@ const (
 	sandboxIDLabelKey           = "io.kubernetes.sandbox.id"
 )
 
+// NetworkPluginArgs is the subset of kubelet runtime args we pass
+// to the container runtime shim so it can probe for network plugins.
+// In the future we will feed these directly to a standalone container
+// runtime process.
+type NetworkPluginSettings struct {
+	// HairpinMode is best described by comments surrounding the kubelet arg
+	HairpinMode componentconfig.HairpinMode
+	// NonMasqueradeCIDR is the range of ips which should *not* be included
+	// in any MASQUERADE rules applied by the plugin
+	NonMasqueradeCIDR string
+	// PluginName is the name of the plugin, runtime shim probes for
+	PluginName string
+	// PluginBinDir is the directory in which the binaries for the plugin with
+	// PluginName is kept. The admin is responsible for provisioning these
+	// binaries before-hand.
+	PluginBinDir string
+	// PluginConfDir is the directory in which the admin places a CNI conf.
+	// Depending on the plugin, this may be an optional field, eg: kubenet
+	// generates its own plugin conf.
+	PluginConfDir string
+	// MTU is the desired MTU for network devices created by the plugin.
+	MTU int
+
+	// RuntimeHost is an interface that serves as a trap-door from plugin back
+	// into the kubelet.
+	// TODO: This shouldn't be required, remove once we move host
+	// ports into CNI.
+	RuntimeHost network.Host
+}
+
 var internalLabelKeys []string = []string{containerTypeLabelKey, containerLogPathLabelKey, sandboxIDLabelKey}
 
 // NOTE: Anything passed to DockerService should be eventually handled in another way when we switch to running the shim as a different process.
-func NewDockerService(client dockertools.DockerInterface, seccompProfileRoot string, podSandboxImage string, streamingConfig *streaming.Config) (DockerService, error) {
+func NewDockerService(client dockertools.DockerInterface, seccompProfileRoot string, podSandboxImage string, streamingConfig *streaming.Config, pluginSettings *NetworkPluginSettings) (DockerService, error) {
 	ds := &dockerService{
 		seccompProfileRoot: seccompProfileRoot,
 		client:             dockertools.NewInstrumentedDockerInterface(client),
@@ -76,6 +110,14 @@ func NewDockerService(client dockertools.DockerInterface, seccompProfileRoot str
 			return nil, err
 		}
 	}
+	// dockershim currently only supports CNI plugins.
+	cniPlugins := cni.ProbeNetworkPlugins(pluginSettings.PluginConfDir, pluginSettings.PluginBinDir)
+	cniPlugins = append(cniPlugins, kubenet.NewPlugin(pluginSettings.PluginBinDir))
+	plug, err := network.InitNetworkPlugin(cniPlugins, pluginSettings.PluginName, pluginSettings.RuntimeHost, pluginSettings.HairpinMode, pluginSettings.NonMasqueradeCIDR, pluginSettings.MTU)
+	if err != nil {
+		return nil, fmt.Errorf("didn't find compatible CNI plugin with given settings %+v: %v", pluginSettings, err)
+	}
+	ds.networkPlugin = plug
 	return ds, nil
 }
 
@@ -105,6 +147,7 @@ type dockerService struct {
 	podSandboxImage    string
 	streamingRuntime   *streamingRuntime
 	streamingServer    streaming.Server
+	networkPlugin      network.NetworkPlugin
 }
 
 // Version returns the runtime name, runtime version and runtime API version

pkg/kubelet/kubelet.go

@@ -482,6 +482,20 @@ func NewMainKubelet(kubeCfg *componentconfig.KubeletConfiguration, kubeDeps *Kub
 		}
 	}
 
+	binDir := kubeCfg.CNIBinDir
+	if binDir == "" {
+		binDir = kubeCfg.NetworkPluginDir
+	}
+	pluginSettings := dockershim.NetworkPluginSettings{
+		HairpinMode:       klet.hairpinMode,
+		NonMasqueradeCIDR: klet.nonMasqueradeCIDR,
+		PluginName:        kubeCfg.NetworkPluginName,
+		PluginConfDir:     kubeCfg.CNIConfDir,
+		PluginBinDir:      binDir,
+		MTU:               int(kubeCfg.NetworkPluginMTU),
+		RuntimeHost:       &networkHost{klet},
+	}
+
 	// Initialize the runtime.
 	switch kubeCfg.ContainerRuntime {
 	case "docker":
@@ -489,10 +503,7 @@ func NewMainKubelet(kubeCfg *componentconfig.KubeletConfiguration, kubeDeps *Kub
 		case "cri":
 			// Use the new CRI shim for docker. This is needed for testing the
 			// docker integration through CRI, and may be removed in the future.
-			dockerService, err := dockershim.NewDockerService(klet.dockerClient, kubeCfg.SeccompProfileRoot, kubeCfg.PodInfraContainerImage, nil)
-			if err != nil {
-				return nil, err
-			}
+			dockerService, err := dockershim.NewDockerService(klet.dockerClient, kubeCfg.SeccompProfileRoot, kubeCfg.PodInfraContainerImage, nil, &pluginSettings)
 			runtimeService := dockerService.(internalApi.RuntimeService)
 			imageService := dockerService.(internalApi.ImageManagerService)
 
@@ -520,6 +531,13 @@ func NewMainKubelet(kubeCfg *componentconfig.KubeletConfiguration, kubeDeps *Kub
 					return nil, err
 				}
 			}
+
+			// kubelet defers to the runtime shim to setup networking. Setting
+			// this to nil will prevent it from trying to invoke the plugin.
+			// It's easier to always probe and initialize plugins till cri
+			// becomes the default.
+			klet.networkPlugin = nil
+
 			klet.containerRuntime, err = kuberuntime.NewKubeGenericRuntimeManager(
 				kubecontainer.FilterEventRecorder(kubeDeps.Recorder),
 				klet.livenessManager,
@@ -1202,6 +1220,13 @@ func (kl *Kubelet) Run(updates <-chan kubetypes.PodUpdate) {
 	kl.syncLoop(updates, kl)
 }
 
+// GetKubeClient returns the Kubernetes client.
+// TODO: This is currently only required by network plugins. Replace
+// with more specific methods.
+func (kl *Kubelet) GetKubeClient() clientset.Interface {
+	return kl.kubeClient
+}
+
 // GetClusterDNS returns a list of the DNS servers and a list of the DNS search
 // domains of the cluster.
 func (kl *Kubelet) GetClusterDNS(pod *api.Pod) ([]string, []string, error) {

pkg/kubelet/kubelet_network.go

@@ -191,7 +191,17 @@ func (kl *Kubelet) cleanupBandwidthLimits(allPods []*api.Pod) error {
 
 // syncNetworkStatus updates the network state
 func (kl *Kubelet) syncNetworkStatus() {
-	kl.runtimeState.setNetworkState(kl.networkPlugin.Status())
+	// TODO(#35701): cri shim handles network plugin but we currently
+	// don't have a cri status hook, so network plugin status isn't
+	// reported if --experimental-runtime-integration=cri. This isn't
+	// too bad, because kubenet is the only network plugin that
+	// implements status(), and it just checks for plugin binaries
+	// on the filesystem.
+	if kl.networkPlugin != nil {
+		kl.runtimeState.setNetworkState(kl.networkPlugin.Status())
+	} else {
+		kl.runtimeState.setNetworkState(nil)
+	}
 }
 
 // updatePodCIDR updates the pod CIDR in the runtime state if it is different
@@ -219,6 +229,16 @@ func (kl *Kubelet) shapingEnabled() bool {
 	if kl.networkPlugin != nil && kl.networkPlugin.Capabilities().Has(network.NET_PLUGIN_CAPABILITY_SHAPING) {
 		return false
 	}
+	// This is not strictly true but we need to figure out how to handle
+	// bandwidth shaping anyway. If the kubelet doesn't have a networkPlugin,
+	// it could mean:
+	// a. the kubelet is responsible for bandwidth shaping
+	// b. the kubelet is using cri, and the cri has a network plugin
+	// Today, the only plugin that understands bandwidth shaping is kubenet, and
+	// it doesn't support bandwidth shaping when invoked through cri, so it
+	// effectively boils down to letting the kubelet decide how to handle
+	// shaping annotations. The combination of (cri + network plugin that
+	// handles bandwidth shaping) may not work because of this.
 	return true
 }