@@ -44,14 +44,13 @@ type stateBackend interface {

 	ContainerUnpause(name string) error

 	ContainerUpdate(name string, hostConfig *container.HostConfig) ([]string, error)

 	ContainerWait(name string, timeout time.Duration) (int, error)

-	Exists(id string) bool

 }

 // monitorBackend includes functions to implement to provide containers monitoring functionality.

 type monitorBackend interface {

 	ContainerChanges(name string) ([]archive.Change, error)

 	ContainerInspect(name string, size bool, version version.Version) (interface{}, error)

-	ContainerLogs(name string, config *backend.ContainerLogsConfig) error

+	ContainerLogs(name string, config *backend.ContainerLogsConfig, started chan struct{}) error

 	ContainerStats(name string, config *backend.ContainerStatsConfig) error

 	ContainerTop(name string, psArgs string) (*types.ContainerProcessList, error)

@@ -3,7 +3,6 @@ package container

 import (

 	"encoding/json"

 	"fmt"

-	"io"

 	"net/http"

 	"strconv"

 	"strings"

@@ -15,7 +14,6 @@ import (

 	"github.com/docker/docker/api/server/httputils"

 	"github.com/docker/docker/api/types/backend"

 	derr "github.com/docker/docker/errors"

-	"github.com/docker/docker/pkg/ioutils"

 	"github.com/docker/docker/pkg/signal"

 	"github.com/docker/docker/pkg/term"

 	"github.com/docker/docker/runconfig"

@@ -66,14 +64,8 @@ func (s *containerRouter) getContainersStats(ctx context.Context, w http.Respons

 	}

 	stream := httputils.BoolValueOrDefault(r, "stream", true)

-	var out io.Writer

 	if !stream {

 		w.Header().Set("Content-Type", "application/json")

-		out = w

-	} else {

-		wf := ioutils.NewWriteFlusher(w)

-		out = wf

-		defer wf.Close()

 	}

 	var closeNotifier <-chan bool

@@ -83,7 +75,7 @@ func (s *containerRouter) getContainersStats(ctx context.Context, w http.Respons

 	config := &backend.ContainerStatsConfig{

 		Stream:    stream,

-		OutStream: out,

+		OutStream: w,

 		Stop:      closeNotifier,

 		Version:   string(httputils.VersionFromContext(ctx)),

 	}

@@ -112,22 +104,6 @@ func (s *containerRouter) getContainersLogs(ctx context.Context, w http.Response

 	}

 	containerName := vars["name"]

-

-	if !s.backend.Exists(containerName) {

-		return derr.ErrorCodeNoSuchContainer.WithArgs(containerName)

-	}

-

-	// write an empty chunk of data (this is to ensure that the

-	// HTTP Response is sent immediately, even if the container has

-	// not yet produced any data)

-	w.WriteHeader(http.StatusOK)

-	if flusher, ok := w.(http.Flusher); ok {

-		flusher.Flush()

-	}

-

-	output := ioutils.NewWriteFlusher(w)

-	defer output.Close()

-

 	logsConfig := &backend.ContainerLogsConfig{

 		ContainerLogsOptions: types.ContainerLogsOptions{

 			Follow:     httputils.BoolValue(r, "follow"),

@@ -137,15 +113,21 @@ func (s *containerRouter) getContainersLogs(ctx context.Context, w http.Response

 			ShowStdout: stdout,

 			ShowStderr: stderr,

 		},

-		OutStream: output,

+		OutStream: w,

 		Stop:      closeNotifier,

 	}

-	if err := s.backend.ContainerLogs(containerName, logsConfig); err != nil {

-		// The client may be expecting all of the data we're sending to

-		// be multiplexed, so send it through OutStream, which will

-		// have been set up to handle that if needed.

-		fmt.Fprintf(logsConfig.OutStream, "Error running logs job: %s\n", utils.GetErrorMessage(err))

+	chStarted := make(chan struct{})

+	if err := s.backend.ContainerLogs(containerName, logsConfig, chStarted); err != nil {

+		select {

+		case <-chStarted:

+			// The client may be expecting all of the data we're sending to

+			// be multiplexed, so send it through OutStream, which will

+			// have been set up to handle that if needed.

+			fmt.Fprintf(logsConfig.OutStream, "Error running logs job: %s\n", utils.GetErrorMessage(err))

+		default:

+			return err

+		}

 	}

 	return nil

@@ -463,10 +445,6 @@ func (s *containerRouter) wsContainersAttach(ctx context.Context, w http.Respons

 	}

 	containerName := vars["name"]

-	if !s.backend.Exists(containerName) {

-		return derr.ErrorCodeNoSuchContainer.WithArgs(containerName)

-	}

-

 	var keys []byte

 	var err error

 	detachKeys := r.FormValue("detachKeys")

@@ -68,16 +68,9 @@ func (s *systemRouter) getEvents(ctx context.Context, w http.ResponseWriter, r *

 	}

 	w.Header().Set("Content-Type", "application/json")

-

-	// This is to ensure that the HTTP status code is sent immediately,

-	// so that it will not block the receiver.

-	w.WriteHeader(http.StatusOK)

-	if flusher, ok := w.(http.Flusher); ok {

-		flusher.Flush()

-	}

-

 	output := ioutils.NewWriteFlusher(w)

 	defer output.Close()

+	output.Flush()

 	enc := json.NewEncoder(output)

@@ -11,13 +11,14 @@ import (

 	"github.com/docker/docker/daemon/logger"

 	"github.com/docker/docker/daemon/logger/jsonfilelog"

 	derr "github.com/docker/docker/errors"

+	"github.com/docker/docker/pkg/ioutils"

 	"github.com/docker/docker/pkg/stdcopy"

 	timetypes "github.com/docker/engine-api/types/time"

 )

 // ContainerLogs hooks up a container's stdout and stderr streams

 // configured with the given struct.

-func (daemon *Daemon) ContainerLogs(containerName string, config *backend.ContainerLogsConfig) error {

+func (daemon *Daemon) ContainerLogs(containerName string, config *backend.ContainerLogsConfig, started chan struct{}) error {

 	container, err := daemon.GetContainer(containerName)

 	if err != nil {

 		return derr.ErrorCodeNoSuchContainer.WithArgs(containerName)

@@ -27,14 +28,6 @@ func (daemon *Daemon) ContainerLogs(containerName string, config *backend.Contai

 		return derr.ErrorCodeNeedStream

 	}

-	outStream := config.OutStream

-	errStream := outStream

-	if !container.Config.Tty {

-		errStream = stdcopy.NewStdWriter(outStream, stdcopy.Stderr)

-		outStream = stdcopy.NewStdWriter(outStream, stdcopy.Stdout)

-	}

-	config.OutStream = outStream

-

 	cLog, err := daemon.getLogger(container)

 	if err != nil {

 		return err

@@ -67,6 +60,18 @@ func (daemon *Daemon) ContainerLogs(containerName string, config *backend.Contai

 	}

 	logs := logReader.ReadLogs(readConfig)

+	wf := ioutils.NewWriteFlusher(config.OutStream)

+	defer wf.Close()

+	close(started)

+	wf.Flush()

+

+	var outStream io.Writer = wf

+	errStream := outStream

+	if !container.Config.Tty {

+		errStream = stdcopy.NewStdWriter(outStream, stdcopy.Stderr)

+		outStream = stdcopy.NewStdWriter(outStream, stdcopy.Stdout)

+	}

+

 	for {

 		select {

 		case err := <-logs.Err:

@@ -7,6 +7,7 @@ import (

 	"github.com/docker/docker/api/types/backend"

 	"github.com/docker/docker/daemon/execdriver"

+	"github.com/docker/docker/pkg/ioutils"

 	"github.com/docker/docker/pkg/version"

 	"github.com/docker/engine-api/types"

 	"github.com/docker/engine-api/types/versions/v1p20"

@@ -31,11 +32,12 @@ func (daemon *Daemon) ContainerStats(prefixOrName string, config *backend.Contai

 		return json.NewEncoder(config.OutStream).Encode(&types.Stats{})

 	}

+	outStream := config.OutStream

 	if config.Stream {

-		// Write an empty chunk of data.

-		// This is to ensure that the HTTP status code is sent immediately,

-		// even if the container has not yet produced any data.

-		config.OutStream.Write(nil)

+		wf := ioutils.NewWriteFlusher(outStream)

+		defer wf.Close()

+		wf.Flush()

+		outStream = wf

 	}

 	var preCPUStats types.CPUStats

@@ -50,7 +52,7 @@ func (daemon *Daemon) ContainerStats(prefixOrName string, config *backend.Contai

 		return ss

 	}

-	enc := json.NewEncoder(config.OutStream)

+	enc := json.NewEncoder(outStream)

 	updates := daemon.subscribeToContainerStats(container)

 	defer daemon.unsubscribeToContainerStats(container, updates)