Merge pull request #5817 from dmcgowan/shim-plugins

Add support for shim plugins

pkg/cri/server/service.go

@@ -65,7 +65,7 @@ type CRIService interface {
 	Run() error
 	// io.Closer is used by containerd to gracefully stop cri service.
 	io.Closer
-	plugin.Service
+	Register(*grpc.Server) error
 	grpcServices
 }
 

plugin/plugin.go

@@ -20,9 +20,7 @@ import (
 	"fmt"
 	"sync"
 
-	"github.com/containerd/ttrpc"
 	"github.com/pkg/errors"
-	"google.golang.org/grpc"
 )
 
 var (
@@ -63,6 +61,8 @@ const (
 	ServicePlugin Type = "io.containerd.service.v1"
 	// GRPCPlugin implements a grpc service
 	GRPCPlugin Type = "io.containerd.grpc.v1"
+	// TTRPCPlugin implements a ttrpc shim service
+	TTRPCPlugin Type = "io.containerd.ttrpc.v1"
 	// SnapshotPlugin implements a snapshotter
 	SnapshotPlugin Type = "io.containerd.snapshotter.v1"
 	// TaskMonitorPlugin implements a task monitor
@@ -124,21 +124,6 @@ func (r *Registration) URI() string {
 	return fmt.Sprintf("%s.%s", r.Type, r.ID)
 }
 
-// Service allows GRPC services to be registered with the underlying server
-type Service interface {
-	Register(*grpc.Server) error
-}
-
-// TTRPCService allows TTRPC services to be registered with the underlying server
-type TTRPCService interface {
-	RegisterTTRPC(*ttrpc.Server) error
-}
-
-// TCPService allows GRPC services to be registered with the underlying tcp server
-type TCPService interface {
-	RegisterTCP(*grpc.Server) error
-}
-
 var register = struct {
 	sync.RWMutex
 	r []*Registration

runtime/v2/shim/shim.go

@@ -30,6 +30,7 @@ import (
 	"github.com/containerd/containerd/events"
 	"github.com/containerd/containerd/log"
 	"github.com/containerd/containerd/namespaces"
+	"github.com/containerd/containerd/plugin"
 	shimapi "github.com/containerd/containerd/runtime/v2/task"
 	"github.com/containerd/containerd/version"
 	"github.com/containerd/ttrpc"
@@ -38,13 +39,6 @@ import (
 	"github.com/sirupsen/logrus"
 )
 
-// Client for a shim server
-type Client struct {
-	service shimapi.TaskService
-	context context.Context
-	signals chan os.Signal
-}
-
 // Publisher for events
 type Publisher interface {
 	events.Publisher
@@ -64,7 +58,6 @@ type Init func(context.Context, string, Publisher, func()) (Shim, error)
 
 // Shim server interface
 type Shim interface {
-	shimapi.TaskService
 	Cleanup(ctx context.Context) (*shimapi.DeleteResponse, error)
 	StartShim(ctx context.Context, opts StartOpts) (string, error)
 }
@@ -91,6 +84,19 @@ type Config struct {
 	NoSetupLogger bool
 }
 
+type ttrpcService interface {
+	RegisterTTRPC(*ttrpc.Server) error
+}
+
+type taskService struct {
+	local shimapi.TaskService
+}
+
+func (t *taskService) RegisterTTRPC(server *ttrpc.Server) error {
+	shimapi.RegisterTaskService(server, t.local)
+	return nil
+}
+
 var (
 	debugFlag            bool
 	versionFlag          bool
@@ -158,6 +164,7 @@ func Run(id string, initFunc Init, opts ...BinaryOpts) {
 	for _, o := range opts {
 		o(&config)
 	}
+
 	if err := run(id, initFunc, config); err != nil {
 		fmt.Fprintf(os.Stderr, "%s: %s\n", id, err)
 		os.Exit(1)
@@ -208,6 +215,7 @@ func run(id string, initFunc Init, config Config) error {
 		return err
 	}
 
+	// Handle explicit actions
 	switch action {
 	case "delete":
 		logger := logrus.WithFields(logrus.Fields{
@@ -234,6 +242,7 @@ func run(id string, initFunc Init, config Config) error {
 			Address:          addressFlag,
 			TTRPCAddress:     ttrpcAddress,
 		}
+
 		address, err := service.StartShim(ctx, opts)
 		if err != nil {
 			return err
@@ -242,14 +251,100 @@ func run(id string, initFunc Init, config Config) error {
 			return err
 		}
 		return nil
-	default:
+	}
+
 	if !config.NoSetupLogger {
 		if err := setLogger(ctx, idFlag); err != nil {
 			return err
 		}
 	}
-		client := NewShimClient(ctx, service, signals)
+
-		if err := client.Serve(); err != nil {
+	// Register event plugin
+	plugin.Register(&plugin.Registration{
+		Type: plugin.EventPlugin,
+		ID:   "publisher",
+		InitFn: func(ic *plugin.InitContext) (interface{}, error) {
+			return publisher, nil
+		},
+	})
+
+	// If service is an implementation of the task service, register it as a plugin
+	if ts, ok := service.(shimapi.TaskService); ok {
+		plugin.Register(&plugin.Registration{
+			Type: plugin.TTRPCPlugin,
+			ID:   "task",
+			InitFn: func(ic *plugin.InitContext) (interface{}, error) {
+				return &taskService{ts}, nil
+			},
+		})
+	}
+
+	var (
+		initialized   = plugin.NewPluginSet()
+		ttrpcServices = []ttrpcService{}
+	)
+	plugins := plugin.Graph(func(*plugin.Registration) bool { return false })
+	for _, p := range plugins {
+		id := p.URI()
+		log.G(ctx).WithField("type", p.Type).Infof("loading plugin %q...", id)
+
+		initContext := plugin.NewContext(
+			ctx,
+			p,
+			initialized,
+			// NOTE: Root is empty since the shim does not support persistent storage,
+			// shim plugins should make use state directory for writing files to disk.
+			// The state directory will be destroyed when the shim if cleaned up or
+			// on reboot
+			"",
+			bundlePath,
+		)
+		initContext.Address = addressFlag
+		initContext.TTRPCAddress = ttrpcAddress
+
+		// load the plugin specific configuration if it is provided
+		//TODO: Read configuration passed into shim, or from state directory?
+		//if p.Config != nil {
+		//	pc, err := config.Decode(p)
+		//	if err != nil {
+		//		return nil, err
+		//	}
+		//	initContext.Config = pc
+		//}
+
+		result := p.Init(initContext)
+		if err := initialized.Add(result); err != nil {
+			return errors.Wrapf(err, "could not add plugin result to plugin set")
+		}
+
+		instance, err := result.Instance()
+		if err != nil {
+			if plugin.IsSkipPlugin(err) {
+				log.G(ctx).WithError(err).WithField("type", p.Type).Infof("skip loading plugin %q...", id)
+			} else {
+				log.G(ctx).WithError(err).Warnf("failed to load plugin %s", id)
+			}
+			continue
+		}
+
+		if src, ok := instance.(ttrpcService); ok {
+			logrus.WithField("id", id).Debug("registering ttrpc service")
+			ttrpcServices = append(ttrpcServices, src)
+		}
+	}
+
+	server, err := newServer()
+	if err != nil {
+		return errors.Wrap(err, "failed creating server")
+	}
+
+	for _, srv := range ttrpcServices {
+		if err := srv.RegisterTTRPC(server); err != nil {
+			return errors.Wrap(err, "failed to register service")
+		}
+	}
+
+	if err := serve(ctx, server, signals); err != nil {
 		if err != context.Canceled {
 			return err
 		}
@@ -267,21 +362,11 @@ func run(id string, initFunc Init, config Config) error {
 	case <-time.After(5 * time.Second):
 		return errors.New("publisher not closed")
 	}
-	}
 }
 
-// NewShimClient creates a new shim server client
+// serve serves the ttrpc API over a unix socket in the current working directory
-func NewShimClient(ctx context.Context, svc shimapi.TaskService, signals chan os.Signal) *Client {
+// and blocks until the context is canceled
-	s := &Client{
+func serve(ctx context.Context, server *ttrpc.Server, signals chan os.Signal) error {
-		service: svc,
-		context: ctx,
-		signals: signals,
-	}
-	return s
-}
-
-// Serve the shim server
-func (s *Client) Serve() error {
 	dump := make(chan os.Signal, 32)
 	setupDumpStacks(dump)
 
@@ -289,34 +374,8 @@ func (s *Client) Serve() error {
 	if err != nil {
 		return err
 	}
-	server, err := newServer()
-	if err != nil {
-		return errors.Wrap(err, "failed creating server")
-	}
 
-	logrus.Debug("registering ttrpc server")
+	l, err := serveListener(socketFlag)
-	shimapi.RegisterTaskService(server, s.service)
-
-	if err := serve(s.context, server, socketFlag); err != nil {
-		return err
-	}
-	logger := logrus.WithFields(logrus.Fields{
-		"pid":       os.Getpid(),
-		"path":      path,
-		"namespace": namespaceFlag,
-	})
-	go func() {
-		for range dump {
-			dumpStacks(logger)
-		}
-	}()
-	return handleSignals(s.context, logger, s.signals)
-}
-
-// serve serves the ttrpc API over a unix socket at the provided path
-// this function does not block
-func serve(ctx context.Context, server *ttrpc.Server, path string) error {
-	l, err := serveListener(path)
 	if err != nil {
 		return err
 	}
@@ -327,7 +386,17 @@ func serve(ctx context.Context, server *ttrpc.Server, path string) error {
 			logrus.WithError(err).Fatal("containerd-shim: ttrpc server failure")
 		}
 	}()
-	return nil
+	logger := logrus.WithFields(logrus.Fields{
+		"pid":       os.Getpid(),
+		"path":      path,
+		"namespace": namespaceFlag,
+	})
+	go func() {
+		for range dump {
+			dumpStacks(logger)
+		}
+	}()
+	return handleSignals(ctx, logger, signals)
 }
 
 func dumpStacks(logger *logrus.Entry) {

services/server/server.go

@@ -142,13 +142,29 @@ func New(ctx context.Context, config *srvconfig.Config) (*Server, error) {
 
 		tcpServerOpts = append(tcpServerOpts, grpc.Creds(credentials.NewTLS(tlsConfig)))
 	}
+
+	// grpcService allows GRPC services to be registered with the underlying server
+	type grpcService interface {
+		Register(*grpc.Server) error
+	}
+
+	// tcpService allows GRPC services to be registered with the underlying tcp server
+	type tcpService interface {
+		RegisterTCP(*grpc.Server) error
+	}
+
+	// ttrpcService allows TTRPC services to be registered with the underlying server
+	type ttrpcService interface {
+		RegisterTTRPC(*ttrpc.Server) error
+	}
+
 	var (
 		grpcServer = grpc.NewServer(serverOpts...)
 		tcpServer  = grpc.NewServer(tcpServerOpts...)
 
-		grpcServices  []plugin.Service
+		grpcServices  []grpcService
-		tcpServices   []plugin.TCPService
+		tcpServices   []tcpService
-		ttrpcServices []plugin.TTRPCService
+		ttrpcServices []ttrpcService
 
 		s = &Server{
 			grpcServer:  grpcServer,
@@ -211,13 +227,13 @@ func New(ctx context.Context, config *srvconfig.Config) (*Server, error) {
 
 		delete(required, reqID)
 		// check for grpc services that should be registered with the server
-		if src, ok := instance.(plugin.Service); ok {
+		if src, ok := instance.(grpcService); ok {
 			grpcServices = append(grpcServices, src)
 		}
-		if src, ok := instance.(plugin.TTRPCService); ok {
+		if src, ok := instance.(ttrpcService); ok {
 			ttrpcServices = append(ttrpcServices, src)
 		}
-		if service, ok := instance.(plugin.TCPService); ok {
+		if service, ok := instance.(tcpService); ok {
 			tcpServices = append(tcpServices, service)
 		}