sidecar: add sidecar server setup

This server will register all supported
services and listen to a tcp for controller
requests.

Signed-off-by: Rakshith R <rar@redhat.com>

Author: Rakshith-R

sidecar/internal/server/server.go

@@ -0,0 +1,107 @@
+/*
+Copyright 2021 The Kubernetes-CSI-Addons 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 server
+
+import (
+	"errors"
+	"net"
+
+	"google.golang.org/grpc"
+	"k8s.io/klog/v2"
+)
+
+// SidecarService is the interface that is required to be implemented so that
+// the SidecarServer can register the service by calling RegisterService().
+type SidecarService interface {
+	// RegisterService is called by the SidecarServer to add a CSI-Addons
+	// service that can handle requests.
+	RegisterService(server grpc.ServiceRegistrar)
+}
+
+// SidecarServer is the gRPC server that listens on an endpoint
+// where the CSI-Addons requests come in.
+type SidecarServer struct {
+	// URL components to listen on the tcp port
+	scheme   string
+	endpoint string
+
+	server   *grpc.Server
+	services []SidecarService
+}
+
+// NewSidecarServer create a new SidecarServer on the given endpoint. The
+// endpoint should be an ip address. Only tcp ports are supported.
+func NewSidecarServer(endpoint string) *SidecarServer {
+	ss := &SidecarServer{}
+
+	if ss.services == nil {
+		ss.services = make([]SidecarService, 0)
+	}
+
+	ss.scheme = "tcp"
+	ss.endpoint = ":" + endpoint
+
+	return ss
+}
+
+// RegisterService takes the SidecarService and registers it with the
+// SidecarServer gRPC server. This function should be called before Start,
+// where the services are registered on the internal gRPC server.
+func (ss *SidecarServer) RegisterService(svc SidecarService) {
+	ss.services = append(ss.services, svc)
+}
+
+// Init creates the internal gRPC server, and registers the SidecarServices.
+// and starts gRPC server.
+func (ss *SidecarServer) Start() {
+	// create the gRPC server and register services
+	ss.server = grpc.NewServer()
+
+	for _, svc := range ss.services {
+		svc.RegisterService(ss.server)
+	}
+
+	listener, err := net.Listen(ss.scheme, ss.endpoint)
+	if err != nil {
+		klog.Fatalf("failed to listen on %q: %w", listener.Addr().String(), err)
+	}
+
+	ss.serve(listener)
+}
+
+// serve starts the actual process of listening for requests on the gRPC
+// server.
+func (ss *SidecarServer) serve(listener net.Listener) {
+	klog.Infof("Listening for CSI-Addons requests on address: %#v", listener.Addr())
+
+	// start to serve requests
+	err := ss.server.Serve(listener)
+	if err != nil && !errors.Is(err, grpc.ErrServerStopped) {
+		klog.Fatalf("Failed to setup CSI-Addons server: %v", err)
+	}
+
+	klog.Infof("The CSI-Addons server at %q has been stopped", listener.Addr())
+}
+
+// Stop can be used to stop the internal gRPC server.
+func (ss *SidecarServer) Stop() {
+	if ss.server == nil {
+		return
+	}
+
+	ss.server.GracefulStop()
+}

sidecar/main.go

@@ -22,6 +22,7 @@ import (
 
 	"github.com/csi-addons/kubernetes-csi-addons/sidecar/internal/client"
 	"github.com/csi-addons/kubernetes-csi-addons/sidecar/internal/csiaddonsnode"
+	"github.com/csi-addons/kubernetes-csi-addons/sidecar/internal/server"
 
 	"k8s.io/client-go/rest"
 	"k8s.io/klog/v2"
@@ -62,4 +63,8 @@ func main() {
 	if err != nil {
 		klog.Fatalf("Failed to create csiaddonsnode: %v", err)
 	}
+
+	sidecarServer := server.NewSidecarServer(*controllerEndpoint)
+
+	sidecarServer.Start()
 }