libcontainerd: create unstarted tasks

Split task creation and start into two separate method calls in the
libcontainerd API. Clients now have the opportunity to inspect the
freshly-created task and customize its runtime environment before
starting execution of the user-specified binary.

Signed-off-by: Cory Snider <csnider@mirantis.com>

daemon/start.go

@@ -11,6 +11,7 @@ import (
 	"github.com/docker/docker/api/types/events"
 	"github.com/docker/docker/container"
 	"github.com/docker/docker/errdefs"
+	"github.com/docker/docker/internal/compatcontext"
 	"github.com/docker/docker/libcontainerd"
 	"github.com/pkg/errors"
 )
@@ -198,16 +199,32 @@ func (daemon *Daemon) containerStart(ctx context.Context, daemonCfg *configStore
 	if err != nil {
 		return setExitCodeFromError(container.SetExitCode, err)
 	}
-
-	// TODO(mlaventure): we need to specify checkpoint options here
-	tsk, err := ctr.Start(context.TODO(), // Passing ctx to ctr.Start caused integration tests to be stuck in the cleanup phase
-		checkpointDir, container.StreamConfig.Stdin() != nil || container.Config.Tty,
-		container.InitializeStdio)
-	if err != nil {
-		if err := ctr.Delete(context.Background()); err != nil {
+	defer func() {
+		if retErr != nil {
+			if err := ctr.Delete(compatcontext.WithoutCancel(ctx)); err != nil {
 				log.G(ctx).WithError(err).WithField("container", container.ID).
 					Error("failed to delete failed start container")
 			}
+		}
+	}()
+
+	// TODO(mlaventure): we need to specify checkpoint options here
+	tsk, err := ctr.NewTask(context.TODO(), // Passing ctx caused integration tests to be stuck in the cleanup phase
+		checkpointDir, container.StreamConfig.Stdin() != nil || container.Config.Tty,
+		container.InitializeStdio)
+	if err != nil {
+		return setExitCodeFromError(container.SetExitCode, err)
+	}
+	defer func() {
+		if retErr != nil {
+			if err := tsk.ForceDelete(compatcontext.WithoutCancel(ctx)); err != nil {
+				log.G(ctx).WithError(err).WithField("container", container.ID).
+					Error("failed to delete task after fail start")
+			}
+		}
+	}()
+
+	if err := tsk.Start(context.TODO()); err != nil { // passing ctx caused integration tests to be stuck in the cleanup phase
 		return setExitCodeFromError(container.SetExitCode, err)
 	}
 

libcontainerd/local/local_windows.go

@@ -387,7 +387,7 @@ func (c *client) extractResourcesFromSpec(spec *specs.Spec, configuration *hcssh
 	}
 }
 
-func (ctr *container) Start(_ context.Context, _ string, withStdin bool, attachStdio libcontainerdtypes.StdioCallback) (_ libcontainerdtypes.Task, retErr error) {
+func (ctr *container) NewTask(_ context.Context, _ string, withStdin bool, attachStdio libcontainerdtypes.StdioCallback) (_ libcontainerdtypes.Task, retErr error) {
 	ctr.mu.Lock()
 	defer ctr.mu.Unlock()
 
@@ -514,6 +514,11 @@ func (ctr *container) Start(_ context.Context, _ string, withStdin bool, attachS
 	return t, nil
 }
 
+func (*task) Start(context.Context) error {
+	// No-op on Windows.
+	return nil
+}
+
 func (ctr *container) Task(context.Context) (libcontainerdtypes.Task, error) {
 	ctr.mu.Lock()
 	defer ctr.mu.Unlock()

libcontainerd/remote/client.go

@@ -145,8 +145,8 @@ func (c *client) NewContainer(ctx context.Context, id string, ociSpec *specs.Spe
 	return &created, nil
 }
 
-// Start create and start a task for the specified containerd id
-func (c *container) Start(ctx context.Context, checkpointDir string, withStdin bool, attachStdio libcontainerdtypes.StdioCallback) (libcontainerdtypes.Task, error) {
+// NewTask creates a task for the specified containerd id
+func (c *container) NewTask(ctx context.Context, checkpointDir string, withStdin bool, attachStdio libcontainerdtypes.StdioCallback) (libcontainerdtypes.Task, error) {
 	var (
 		checkpoint     *types.Descriptor
 		t              containerd.Task
@@ -236,19 +236,14 @@ func (c *container) Start(ctx context.Context, checkpointDir string, withStdin b
 	// Signal c.createIO that it can call CloseIO
 	stdinCloseSync <- t
 
-	if err := t.Start(ctx); err != nil {
-		// Only Stopped tasks can be deleted. Created tasks have to be
-		// killed first, to transition them to Stopped.
-		if _, err := t.Delete(ctx, containerd.WithProcessKill); err != nil {
-			c.client.logger.WithError(err).WithField("container", c.c8dCtr.ID()).
-				Error("failed to delete task after fail start")
-		}
-		return nil, wrapError(err)
-	}
-
 	return c.newTask(t), nil
 }
 
+func (t *task) Start(ctx context.Context) error {
+	return wrapError(t.Task.Start(ctx))
+
+}
+
 // Exec creates exec process.
 //
 // The containerd client calls Exec to register the exec config in the shim side.

libcontainerd/types/types.go

@@ -64,7 +64,7 @@ type Client interface {
 
 // Container provides access to a containerd container.
 type Container interface {
-	Start(ctx context.Context, checkpointDir string, withStdin bool, attachStdio StdioCallback) (Task, error)
+	NewTask(ctx context.Context, checkpointDir string, withStdin bool, attachStdio StdioCallback) (Task, error)
 	Task(ctx context.Context) (Task, error)
 	// AttachTask returns the current task for the container and reattaches
 	// to the IO for the running task. If no task exists for the container
@@ -79,6 +79,8 @@ type Container interface {
 // Task provides access to a running containerd container.
 type Task interface {
 	Process
+	// Start begins execution of the task
+	Start(context.Context) error
 	// Pause suspends the execution of the task
 	Pause(context.Context) error
 	// Resume the execution of the task

plugin/executor/containerd/containerd.go

@@ -81,11 +81,15 @@ func (e *Executor) Create(id string, spec specs.Spec, stdout, stderr io.WriteClo
 	}
 
 	p := c8dPlugin{log: log.G(ctx).WithField("plugin", id), ctr: ctr}
-	p.tsk, err = ctr.Start(ctx, "", false, attachStreamsFunc(stdout, stderr))
+	p.tsk, err = ctr.NewTask(ctx, "", false, attachStreamsFunc(stdout, stderr))
 	if err != nil {
 		p.deleteTaskAndContainer(ctx)
 		return err
 	}
+	if err := p.tsk.Start(ctx); err != nil {
+		p.deleteTaskAndContainer(ctx)
+		return err
+	}
 	e.mu.Lock()
 	defer e.mu.Unlock()
 	e.plugins[id] = &p