Add probe based mechanism for kubelet plugin discovery

pkg/kubelet/util/pluginwatcher/example_plugin.go

@@ -0,0 +1,150 @@
+/*
+Copyright 2018 The Kubernetes Authors.
+
+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 pluginwatcher
+
+import (
+	"fmt"
+	"net"
+	"sync"
+	"time"
+
+	"github.com/golang/glog"
+	"golang.org/x/net/context"
+	"google.golang.org/grpc"
+
+	registerapi "k8s.io/kubernetes/pkg/kubelet/apis/pluginregistration/v1alpha1"
+	v1beta1 "k8s.io/kubernetes/pkg/kubelet/util/pluginwatcher/example_plugin_apis/v1beta1"
+	v1beta2 "k8s.io/kubernetes/pkg/kubelet/util/pluginwatcher/example_plugin_apis/v1beta2"
+)
+
+const (
+	PluginName = "example-plugin"
+	PluginType = "example-plugin-type"
+)
+
+// examplePlugin is a sample plugin to work with plugin watcher
+type examplePlugin struct {
+	grpcServer         *grpc.Server
+	wg                 sync.WaitGroup
+	registrationStatus chan registerapi.RegistrationStatus // for testing
+	endpoint           string                              // for testing
+}
+
+type pluginServiceV1Beta1 struct {
+	server *examplePlugin
+}
+
+func (s *pluginServiceV1Beta1) GetExampleInfo(ctx context.Context, rqt *v1beta1.ExampleRequest) (*v1beta1.ExampleResponse, error) {
+	glog.Infof("GetExampleInfo v1beta1field: %s", rqt.V1Beta1Field)
+	return &v1beta1.ExampleResponse{}, nil
+}
+
+func (s *pluginServiceV1Beta1) RegisterService() {
+	v1beta1.RegisterExampleServer(s.server.grpcServer, s)
+}
+
+type pluginServiceV1Beta2 struct {
+	server *examplePlugin
+}
+
+func (s *pluginServiceV1Beta2) GetExampleInfo(ctx context.Context, rqt *v1beta2.ExampleRequest) (*v1beta2.ExampleResponse, error) {
+	glog.Infof("GetExampleInfo v1beta2_field: %s", rqt.V1Beta2Field)
+	return &v1beta2.ExampleResponse{}, nil
+}
+
+func (s *pluginServiceV1Beta2) RegisterService() {
+	v1beta2.RegisterExampleServer(s.server.grpcServer, s)
+}
+
+// NewExamplePlugin returns an initialized examplePlugin instance
+func NewExamplePlugin() *examplePlugin {
+	return &examplePlugin{}
+}
+
+// NewTestExamplePlugin returns an initialized examplePlugin instance for testing
+func NewTestExamplePlugin(endpoint string) *examplePlugin {
+	return &examplePlugin{
+		registrationStatus: make(chan registerapi.RegistrationStatus),
+		endpoint:           endpoint,
+	}
+}
+
+// GetInfo is the RPC invoked by plugin watcher
+func (e *examplePlugin) GetInfo(ctx context.Context, req *registerapi.InfoRequest) (*registerapi.PluginInfo, error) {
+	return &registerapi.PluginInfo{
+		Type:              PluginType,
+		Name:              PluginName,
+		Endpoint:          e.endpoint,
+		SupportedVersions: []string{"v1beta1", "v1beta2"},
+	}, nil
+}
+
+func (e *examplePlugin) NotifyRegistrationStatus(ctx context.Context, status *registerapi.RegistrationStatus) (*registerapi.RegistrationStatusResponse, error) {
+	if e.registrationStatus != nil {
+		e.registrationStatus <- *status
+	}
+	if !status.PluginRegistered {
+		glog.Errorf("Registration failed: %s\n", status.Error)
+	}
+	return &registerapi.RegistrationStatusResponse{}, nil
+}
+
+// Serve starts example plugin grpc server
+func (e *examplePlugin) Serve(socketPath string) error {
+	glog.Infof("starting example server at: %s\n", socketPath)
+	lis, err := net.Listen("unix", socketPath)
+	if err != nil {
+		return err
+	}
+	glog.Infof("example server started at: %s\n", socketPath)
+	e.grpcServer = grpc.NewServer()
+	// Registers kubelet plugin watcher api.
+	registerapi.RegisterRegistrationServer(e.grpcServer, e)
+	// Registers services for both v1beta1 and v1beta2 versions.
+	v1beta1 := &pluginServiceV1Beta1{server: e}
+	v1beta1.RegisterService()
+	v1beta2 := &pluginServiceV1Beta2{server: e}
+	v1beta2.RegisterService()
+
+	// Starts service
+	e.wg.Add(1)
+	go func() {
+		defer e.wg.Done()
+		// Blocking call to accept incoming connections.
+		if err := e.grpcServer.Serve(lis); err != nil {
+			glog.Errorf("example server stopped serving: %v", err)
+		}
+	}()
+	return nil
+}
+
+func (e *examplePlugin) Stop() error {
+	glog.Infof("Stopping example server\n")
+	e.grpcServer.Stop()
+	c := make(chan struct{})
+	go func() {
+		defer close(c)
+		e.wg.Wait()
+	}()
+	select {
+	case <-c:
+		return nil
+	case <-time.After(time.Second):
+		glog.Errorf("Timed out on waiting for stop completion")
+		return fmt.Errorf("Timed out on waiting for stop completion")
+	}
+}