Initial GRPC client support

Signed-off-by: Maksym Pavlenko <pavlenko.maksym@gmail.com>

runtime/v2/shim.go

@@ -23,8 +23,13 @@ import (
 	"io"
 	"os"
 	"path/filepath"
+	"strings"
 	"time"
 
+	"github.com/containerd/ttrpc"
+	"github.com/hashicorp/go-multierror"
+	"google.golang.org/grpc"
+
 	eventstypes "github.com/containerd/containerd/api/events"
 	"github.com/containerd/containerd/api/runtime/task/v2"
 	"github.com/containerd/containerd/api/types"
@@ -32,13 +37,12 @@ import (
 	"github.com/containerd/containerd/events/exchange"
 	"github.com/containerd/containerd/identifiers"
 	"github.com/containerd/containerd/log"
+	"github.com/containerd/containerd/pkg/dialer"
 	"github.com/containerd/containerd/pkg/timeout"
 	"github.com/containerd/containerd/protobuf"
 	ptypes "github.com/containerd/containerd/protobuf/types"
 	"github.com/containerd/containerd/runtime"
 	client "github.com/containerd/containerd/runtime/v2/shim"
-	"github.com/containerd/ttrpc"
-	"github.com/hashicorp/go-multierror"
 )
 
 const (
@@ -61,23 +65,18 @@ func loadAddress(path string) (string, error) {
 	return string(data), nil
 }
 
-func loadShim(ctx context.Context, bundle *Bundle, onClose func()) (_ ShimInstance, err error) {
+func loadShim(ctx context.Context, bundle *Bundle, onClose func()) (_ ShimInstance, retErr error) {
 	address, err := loadAddress(filepath.Join(bundle.Path, "address"))
 	if err != nil {
 		return nil, err
 	}
-	conn, err := client.Connect(address, client.AnonReconnectDialer)
-	if err != nil {
-		return nil, err
-	}
-	defer func() {
-		if err != nil {
-			conn.Close()
-		}
-	}()
+
+	// TODO: figure out how to negotiate protocol between containerd and shim
+	isGRPC := strings.Contains(strings.ToLower(address), "grpc")
+
 	shimCtx, cancelShimLog := context.WithCancel(ctx)
 	defer func() {
-		if err != nil {
+		if retErr != nil {
 			cancelShimLog()
 		}
 	}()
@@ -86,7 +85,7 @@ func loadShim(ctx context.Context, bundle *Bundle, onClose func()) (_ ShimInstan
 		return nil, fmt.Errorf("open shim log pipe when reload: %w", err)
 	}
 	defer func() {
-		if err != nil {
+		if retErr != nil {
 			f.Close()
 		}
 	}()
@@ -109,16 +108,51 @@ func loadShim(ctx context.Context, bundle *Bundle, onClose func()) (_ ShimInstan
 		cancelShimLog()
 		f.Close()
 	}
-	client := ttrpc.NewClient(conn, ttrpc.WithOnClose(onCloseWithShimLog))
-	defer func() {
+
+	shim := &shim{bundle: bundle}
+
+	if !isGRPC {
+		conn, err := client.Connect(address, client.AnonReconnectDialer)
 		if err != nil {
-			client.Close()
+			return nil, fmt.Errorf("failed to create TTRPC connection: %w", err)
+		}
+		defer func() {
+			if retErr != nil {
+				conn.Close()
 			}
 		}()
-	shim := &shim{
-		bundle: bundle,
-		client: client,
+
+		ttrpcClient := ttrpc.NewClient(conn, ttrpc.WithOnClose(onCloseWithShimLog))
+		defer func() {
+			if retErr != nil {
+				ttrpcClient.Close()
 			}
+		}()
+
+		shim.client = ttrpcClient
+	} else {
+		// GRPC shim
+
+		var (
+			gopts []grpc.DialOption
+		)
+
+		conn, err := grpc.DialContext(ctx, dialer.DialAddress(address), gopts...)
+		if err != nil {
+			return nil, fmt.Errorf("failed to create GRPC connection: %w", err)
+		}
+
+		defer func() {
+			if retErr != nil {
+				conn.Close()
+			}
+		}()
+
+		// TODO: figure out how to invoke onCloseWithShimLog callback when shim connection is closed.
+
+		shim.client = conn
+	}
+
 	ctx, cancel := timeout.WithContext(ctx, loadTimeout)
 	defer cancel()
 
@@ -131,6 +165,7 @@ func loadShim(ctx context.Context, bundle *Bundle, onClose func()) (_ ShimInstan
 	if _, err := s.PID(ctx); err != nil {
 		return nil, err
 	}
+
 	return shim, nil
 }
 
@@ -189,15 +224,16 @@ type ShimInstance interface {
 	Namespace() string
 	// Bundle is a file system path to shim's bundle.
 	Bundle() string
-	// Client returns the underlying TTRPC client for this shim.
-	Client() interface{}
+	// Client returns the underlying TTRPC or GRPC client object for this shim.
+	// The underlying object can be either *ttrpc.Client or grpc.ClientConnInterface.
+	Client() any
 	// Delete will close the client and remove bundle from disk.
 	Delete(ctx context.Context) error
 }
 
 type shim struct {
 	bundle *Bundle
-	client *ttrpc.Client
+	client any
 }
 
 var _ ShimInstance = (*shim)(nil)
@@ -215,13 +251,17 @@ func (s *shim) Bundle() string {
 	return s.bundle.Path
 }
 
-func (s *shim) Client() interface{} {
+func (s *shim) Client() any {
 	return s.client
 }
 
 // Close closes the underlying client connection.
 func (s *shim) Close() error {
-	return s.client.Close()
+	if ttrpcClient, ok := s.client.(*ttrpc.Client); ok {
+		return ttrpcClient.Close()
+	}
+
+	return nil
 }
 
 func (s *shim) Delete(ctx context.Context) error {
@@ -229,13 +269,15 @@ func (s *shim) Delete(ctx context.Context) error {
 		result *multierror.Error
 	)
 
-	if err := s.client.Close(); err != nil {
+	if ttrpcClient, ok := s.client.(*ttrpc.Client); ok {
+		if err := ttrpcClient.Close(); err != nil {
 			result = multierror.Append(result, fmt.Errorf("failed to close ttrpc client: %w", err))
 		}
 
-	if err := s.client.UserOnCloseWait(ctx); err != nil {
+		if err := ttrpcClient.UserOnCloseWait(ctx); err != nil {
 			result = multierror.Append(result, fmt.Errorf("close wait error: %w", err))
 		}
+	}
 
 	if err := s.bundle.Delete(); err != nil {
 		log.G(ctx).WithField("id", s.ID()).WithError(err).Error("failed to delete bundle")