@@ -26,6 +26,7 @@ func NewServiceCommand(dockerCli *command.DockerCli) *cobra.Command {

 		newRemoveCommand(dockerCli),

 		newScaleCommand(dockerCli),

 		newUpdateCommand(dockerCli),

+		newLogsCommand(dockerCli),

 	)

 	return cmd

 }

new file mode 100644

@@ -0,0 +1,163 @@

+package service

+

+import (

+	"bytes"

+	"fmt"

+	"io"

+	"strings"

+

+	"golang.org/x/net/context"

+

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

+	"github.com/docker/docker/api/types/swarm"

+	"github.com/docker/docker/cli"

+	"github.com/docker/docker/cli/command"

+	"github.com/docker/docker/cli/command/idresolver"

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

+	"github.com/spf13/cobra"

+)

+

+type logsOptions struct {

+	noResolve  bool

+	follow     bool

+	since      string

+	timestamps bool

+	details    bool

+	tail       string

+

+	service string

+}

+

+func newLogsCommand(dockerCli *command.DockerCli) *cobra.Command {

+	var opts logsOptions

+

+	cmd := &cobra.Command{

+		Use:   "logs [OPTIONS] SERVICE",

+		Short: "Fetch the logs of a service",

+		Args:  cli.ExactArgs(1),

+		RunE: func(cmd *cobra.Command, args []string) error {

+			opts.service = args[0]

+			return runLogs(dockerCli, &opts)

+		},

+		Tags: map[string]string{"experimental": ""},

+	}

+

+	flags := cmd.Flags()

+	flags.BoolVar(&opts.noResolve, "no-resolve", false, "Do not map IDs to Names")

+	flags.BoolVarP(&opts.follow, "follow", "f", false, "Follow log output")

+	flags.StringVar(&opts.since, "since", "", "Show logs since timestamp")

+	flags.BoolVarP(&opts.timestamps, "timestamps", "t", false, "Show timestamps")

+	flags.BoolVar(&opts.details, "details", false, "Show extra details provided to logs")

+	flags.StringVar(&opts.tail, "tail", "all", "Number of lines to show from the end of the logs")

+	return cmd

+}

+

+func runLogs(dockerCli *command.DockerCli, opts *logsOptions) error {

+	ctx := context.Background()

+

+	options := types.ContainerLogsOptions{

+		ShowStdout: true,

+		ShowStderr: true,

+		Since:      opts.since,

+		Timestamps: opts.timestamps,

+		Follow:     opts.follow,

+		Tail:       opts.tail,

+		Details:    opts.details,

+	}

+

+	client := dockerCli.Client()

+	responseBody, err := client.ServiceLogs(ctx, opts.service, options)

+	if err != nil {

+		return err

+	}

+	defer responseBody.Close()

+

+	resolver := idresolver.New(client, opts.noResolve)

+

+	stdout := &logWriter{ctx: ctx, opts: opts, r: resolver, w: dockerCli.Out()}

+	stderr := &logWriter{ctx: ctx, opts: opts, r: resolver, w: dockerCli.Err()}

+

+	// TODO(aluzzardi): Do an io.Copy for services with TTY enabled.

+	_, err = stdcopy.StdCopy(stdout, stderr, responseBody)

+	return err

+}

+

+type logWriter struct {

+	ctx  context.Context

+	opts *logsOptions

+	r    *idresolver.IDResolver

+	w    io.Writer

+}

+

+func (lw *logWriter) Write(buf []byte) (int, error) {

+	contextIndex := 0

+	numParts := 2

+	if lw.opts.timestamps {

+		contextIndex++

+		numParts++

+	}

+

+	parts := bytes.SplitN(buf, []byte(" "), numParts)

+	if len(parts) != numParts {

+		return 0, fmt.Errorf("invalid context in log message: %v", string(buf))

+	}

+

+	taskName, nodeName, err := lw.parseContext(string(parts[contextIndex]))

+	if err != nil {

+		return 0, err

+	}

+

+	output := []byte{}

+	for i, part := range parts {

+		// First part doesn't get space separation.

+		if i > 0 {

+			output = append(output, []byte(" ")...)

+		}

+

+		if i == contextIndex {

+			// TODO(aluzzardi): Consider constant padding.

+			output = append(output, []byte(fmt.Sprintf("%s@%s    |", taskName, nodeName))...)

+		} else {

+			output = append(output, part...)

+		}

+	}

+	_, err = lw.w.Write(output)

+	if err != nil {

+		return 0, err

+	}

+

+	return len(buf), nil

+}

+

+func (lw *logWriter) parseContext(input string) (string, string, error) {

+	context := make(map[string]string)

+

+	components := strings.Split(input, ",")

+	for _, component := range components {

+		parts := strings.SplitN(component, "=", 2)

+		if len(parts) != 2 {

+			return "", "", fmt.Errorf("invalid context: %s", input)

+		}

+		context[parts[0]] = parts[1]

+	}

+

+	taskID, ok := context["com.docker.swarm.task.id"]

+	if !ok {

+		return "", "", fmt.Errorf("missing task id in context: %s", input)

+	}

+	taskName, err := lw.r.Resolve(lw.ctx, swarm.Task{}, taskID)

+	if err != nil {

+		return "", "", err

+	}

+

+	nodeID, ok := context["com.docker.swarm.node.id"]

+	if !ok {

+		return "", "", fmt.Errorf("missing node id in context: %s", input)

+	}

+	nodeName, err := lw.r.Resolve(lw.ctx, swarm.Node{}, nodeID)

+	if err != nil {

+		return "", "", err

+	}

+

+	return taskName, nodeName, nil

+}

new file mode 100644

@@ -0,0 +1,55 @@

+// +build !windows

+

+package main

+

+import (

+	"bufio"

+	"io"

+	"os/exec"

+	"strings"

+

+	"github.com/docker/docker/pkg/integration/checker"

+	"github.com/go-check/check"

+)

+

+type logMessage struct {

+	err  error

+	data []byte

+}

+

+func (s *DockerSwarmSuite) TestServiceLogs(c *check.C) {

+	testRequires(c, ExperimentalDaemon)

+

+	d := s.AddDaemon(c, true, true)

+

+	name := "TestServiceLogs"

+

+	out, err := d.Cmd("service", "create", "--name", name, "busybox", "sh", "-c", "while true; do echo log test; sleep 1; done")

+	c.Assert(err, checker.IsNil)

+	c.Assert(strings.TrimSpace(out), checker.Not(checker.Equals), "")

+

+	// make sure task has been deployed.

+	waitAndAssert(c, defaultReconciliationTimeout, d.checkActiveContainerCount, checker.Equals, 1)

+

+	args := []string{"service", "logs", "-f", name}

+	cmd := exec.Command(dockerBinary, d.prependHostArg(args)...)

+	r, w := io.Pipe()

+	cmd.Stdout = w

+	cmd.Stderr = w

+	c.Assert(cmd.Start(), checker.IsNil)

+

+	// Make sure pipe is written to

+	ch := make(chan *logMessage)

+	go func() {

+		reader := bufio.NewReader(r)

+		msg := &logMessage{}

+		msg.data, _, msg.err = reader.ReadLine()

+		ch <- msg

+	}()

+

+	msg := <-ch

+	c.Assert(msg.err, checker.IsNil)

+	c.Assert(string(msg.data), checker.Contains, "log test")

+

+	c.Assert(cmd.Process.Kill(), checker.IsNil)

+}