Prototype of grpc API

Signed-off-by: Alexander Morozov <lk4d4@docker.com>

containerd/main.go

@@ -2,15 +2,21 @@ package main
 
 import (
 	"log"
+	"net"
 	"net/http"
 	"os"
 	"runtime"
 	"sync"
 	"time"
 
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/grpclog"
+
 	"github.com/Sirupsen/logrus"
 	"github.com/codegangsta/cli"
 	"github.com/docker/containerd"
+	"github.com/docker/containerd/api/grpc/server"
+	"github.com/docker/containerd/api/grpc/types"
 	"github.com/docker/containerd/api/v1"
 	"github.com/rcrowley/go-metrics"
 )
@@ -115,6 +121,16 @@ func daemon(id, stateDir string, concurrency, bufferSize int) error {
 	if err := supervisor.Start(); err != nil {
 		return err
 	}
+	if os.Getenv("GRPC") != "" {
+		lis, err := net.Listen("tcp", ":8888")
+		if err != nil {
+			grpclog.Fatalf("failed to listen: %v", err)
+		}
+		grpcServer := grpc.NewServer()
+		types.RegisterAPIServer(grpcServer, server.NewServer(supervisor))
+		return grpcServer.Serve(lis)
+
+	}
 	server := v1.NewServer(supervisor)
 	return http.ListenAndServe("localhost:8888", server)
 }