VMCache: Update factory to run as a VMCache server

When VMCache is enabled, factory init will run as a VMcache server.

Fixes: #52

Signed-off-by: Hui Zhu <teawater@hyper.sh>

cli/factory.go

@@ -6,13 +6,23 @@
 package main
 
 import (
-	"errors"
+	"context"
 	"fmt"
+	"net"
+	"os"
+	"os/signal"
+	"path/filepath"
+	"syscall"
 
+	"github.com/gogo/protobuf/types"
+	pb "github.com/kata-containers/runtime/protocols/cache"
 	vc "github.com/kata-containers/runtime/virtcontainers"
 	vf "github.com/kata-containers/runtime/virtcontainers/factory"
 	"github.com/kata-containers/runtime/virtcontainers/pkg/oci"
+	"github.com/pkg/errors"
 	"github.com/urfave/cli"
+	"golang.org/x/sys/unix"
+	"google.golang.org/grpc"
 )
 
 var factorySubCmds = []cli.Command{
@@ -30,6 +40,84 @@ var factoryCLICommand = cli.Command{
 	},
 }
 
+type cacheServer struct {
+	rpc     *grpc.Server
+	factory vc.Factory
+}
+
+var jsonVMConfig *pb.GrpcVMConfig
+
+// Config requests base factory config and convert it to gRPC protocol.
+func (s *cacheServer) Config(ctx context.Context, empty *types.Empty) (*pb.GrpcVMConfig, error) {
+	if jsonVMConfig == nil {
+		config := s.factory.Config()
+
+		var err error
+		jsonVMConfig, err = config.ToGrpc()
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	return jsonVMConfig, nil
+}
+
+// GetBaseVM requests a paused VM and convert it to gRPC protocol.
+func (s *cacheServer) GetBaseVM(ctx context.Context, empty *types.Empty) (*pb.GrpcVM, error) {
+	config := s.factory.Config()
+
+	vm, err := s.factory.GetBaseVM(ctx, config)
+	if err != nil {
+		return nil, errors.Wrapf(err, "failed to GetBaseVM")
+	}
+
+	return vm.ToGrpc(config)
+}
+
+func getUnixListener(path string) (net.Listener, error) {
+	err := os.MkdirAll(filepath.Dir(path), 0755)
+	if err != nil {
+		return nil, err
+	}
+	if err = unix.Unlink(path); err != nil && !os.IsNotExist(err) {
+		return nil, err
+	}
+	l, err := net.Listen("unix", path)
+	if err != nil {
+		return nil, err
+	}
+	if err = os.Chmod(path, 0600); err != nil {
+		l.Close()
+		return nil, err
+	}
+	return l, nil
+}
+
+var handledSignals = []os.Signal{
+	syscall.SIGTERM,
+	syscall.SIGINT,
+	syscall.SIGPIPE,
+}
+
+func handleSignals(s *cacheServer, signals chan os.Signal) chan struct{} {
+	done := make(chan struct{}, 1)
+	go func() {
+		for {
+			sig := <-signals
+			kataLog.WithField("signal", sig).Debug("received signal")
+			switch sig {
+			case unix.SIGPIPE:
+				continue
+			default:
+				s.rpc.GracefulStop()
+				close(done)
+				return
+			}
+		}
+	}()
+	return done
+}
+
 var initFactoryCommand = cli.Command{
 	Name:  "init",
 	Usage: "initialize a VM factory based on kata-runtime configuration",
@@ -44,6 +132,51 @@ var initFactoryCommand = cli.Command{
 			return errors.New("invalid runtime config")
 		}
 
+		if runtimeConfig.FactoryConfig.VMCacheNumber > 0 {
+			factoryConfig := vf.Config{
+				Template: runtimeConfig.FactoryConfig.Template,
+				Cache:    runtimeConfig.FactoryConfig.VMCacheNumber,
+				VMCache:  true,
+				VMConfig: vc.VMConfig{
+					HypervisorType:   runtimeConfig.HypervisorType,
+					HypervisorConfig: runtimeConfig.HypervisorConfig,
+					AgentType:        runtimeConfig.AgentType,
+					AgentConfig:      runtimeConfig.AgentConfig,
+					ProxyType:        runtimeConfig.ProxyType,
+					ProxyConfig:      runtimeConfig.ProxyConfig,
+				},
+			}
+			f, err := vf.NewFactory(ctx, factoryConfig, false)
+			if err != nil {
+				return err
+			}
+			defer f.CloseFactory(ctx)
+
+			s := &cacheServer{
+				rpc:     grpc.NewServer(),
+				factory: f,
+			}
+			pb.RegisterCacheServiceServer(s.rpc, s)
+
+			l, err := getUnixListener(runtimeConfig.FactoryConfig.VMCacheEndpoint)
+			if err != nil {
+				return err
+			}
+			defer l.Close()
+
+			signals := make(chan os.Signal, 8)
+			done := handleSignals(s, signals)
+			signal.Notify(signals, handledSignals...)
+
+			kataLog.WithField("endpoint", runtimeConfig.FactoryConfig.VMCacheEndpoint).Info("VM cache server start")
+			s.rpc.Serve(l)
+
+			<-done
+
+			kataLog.WithField("endpoint", runtimeConfig.FactoryConfig.VMCacheEndpoint).Info("VM cache server stop")
+			return nil
+		}
+
 		if runtimeConfig.FactoryConfig.Template {
 			factoryConfig := vf.Config{
 				Template: true,