WIP: add configurable detach delay to logs

Signed-off-by: Laura Brehm <laurabrehm@hey.com>

cli/command/container/logs.go

@@ -3,11 +3,14 @@ package container
 import (
 	"context"
 	"io"
+	"strconv"
+	"time"
 
 	"github.com/docker/cli/cli"
 	"github.com/docker/cli/cli/command"
 	"github.com/docker/cli/cli/command/completion"
 	"github.com/docker/docker/api/types/container"
+	"github.com/docker/docker/api/types/events"
 	"github.com/docker/docker/pkg/stdcopy"
 	"github.com/spf13/cobra"
 )
@@ -20,6 +23,8 @@ type logsOptions struct {
 	details    bool
 	tail       string
 
+	detachDelay int
+
 	container string
 }
 
@@ -49,6 +54,7 @@ func NewLogsCommand(dockerCli command.Cli) *cobra.Command {
 	flags.BoolVarP(&opts.timestamps, "timestamps", "t", false, "Show timestamps")
 	flags.BoolVar(&opts.details, "details", false, "Show extra details provided to logs")
 	flags.StringVarP(&opts.tail, "tail", "n", "all", "Number of lines to show from the end of the logs")
+	flags.IntVarP(&opts.detachDelay, "delay", "d", 0, "Number of seconds to wait for container restart before exiting")
 	return cmd
 }
 
@@ -58,6 +64,45 @@ func runLogs(ctx context.Context, dockerCli command.Cli, opts *logsOptions) erro
 		return err
 	}
 
+	since := opts.since
+	for {
+		restarting := make(chan events.Message)
+		if opts.detachDelay != 0 {
+			go func() {
+				eventsCtx, eventsCtxCancel := context.WithCancel(ctx)
+				eventC, eventErrs := dockerCli.Client().Events(eventsCtx, events.ListOptions{})
+				defer eventsCtxCancel()
+				for {
+					select {
+					case event := <-eventC:
+						if event.Action == events.ActionRestart && event.Actor.ID == c.ID {
+							restarting <- event
+							return
+						}
+					case <-eventErrs:
+						return
+					}
+				}
+			}()
+		}
+
+		opts.since = since
+		err = streamLogs(ctx, dockerCli, opts, c)
+
+		if opts.detachDelay == 0 {
+			return err
+		}
+
+		select {
+		case restartEvent := <-restarting:
+			since = strconv.FormatInt(restartEvent.Time, 10)
+		case <-time.After(time.Duration(opts.detachDelay) * time.Second):
+			return err
+		}
+	}
+}
+
+func streamLogs(ctx context.Context, dockerCli command.Cli, opts *logsOptions, c container.InspectResponse) error {
 	responseBody, err := dockerCli.Client().ContainerLogs(ctx, c.ID, container.LogsOptions{
 		ShowStdout: true,
 		ShowStderr: true,
@@ -78,5 +123,6 @@ func runLogs(ctx context.Context, dockerCli command.Cli, opts *logsOptions) erro
 	} else {
 		_, err = stdcopy.StdCopy(dockerCli.Out(), dockerCli.Err(), responseBody)
 	}
+
 	return err
 }

docs/reference/commandline/container_logs.md

@@ -11,6 +11,7 @@ Fetch the logs of a container
 
 | Name                 | Type     | Default | Description                                                                                        |
 |:---------------------|:---------|:--------|:---------------------------------------------------------------------------------------------------|
+| `-d`, `--delay`      | `int`    | `0`     | Number of seconds to wait for container restart before exiting                                     |
 | `--details`          | `bool`   |         | Show extra details provided to logs                                                                |
 | `-f`, `--follow`     | `bool`   |         | Follow log output                                                                                  |
 | `--since`            | `string` |         | Show logs since timestamp (e.g. `2013-01-02T13:23:37Z`) or relative (e.g. `42m` for 42 minutes)    |

docs/reference/commandline/logs.md

@@ -11,6 +11,7 @@ Fetch the logs of a container
 
 | Name                 | Type     | Default | Description                                                                                        |
 |:---------------------|:---------|:--------|:---------------------------------------------------------------------------------------------------|
+| `-d`, `--delay`      | `int`    | `0`     | Number of seconds to wait for container restart before exiting                                     |
 | `--details`          | `bool`   |         | Show extra details provided to logs                                                                |
 | `-f`, `--follow`     | `bool`   |         | Follow log output                                                                                  |
 | `--since`            | `string` |         | Show logs since timestamp (e.g. `2013-01-02T13:23:37Z`) or relative (e.g. `42m` for 42 minutes)    |

e2e/container/logs_test.go

@@ -0,0 +1,46 @@
+package container
+
+import (
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/docker/cli/e2e/internal/fixtures"
+	"gotest.tools/v3/icmd"
+	"gotest.tools/v3/poll"
+)
+
+func TestLogsReattach(t *testing.T) {
+	result := icmd.RunCommand("docker", "run", "-d", fixtures.AlpineImage,
+		"sh", "-c", "echo hi; while true; do sleep 1; done")
+	result.Assert(t, icmd.Success)
+	containerID := strings.TrimSpace(result.Stdout())
+
+	cmd := icmd.Command("docker", "logs", "-f", "-d", "5", containerID)
+	// cmd := icmd.Command("docker", "logs", containerID)
+	result = icmd.StartCmd(cmd)
+
+	poll.WaitOn(t, func(t poll.LogT) poll.Result {
+		if strings.Contains(result.Stdout(), "hi") {
+			return poll.Success()
+		}
+		return poll.Continue("waiting")
+	}, poll.WithDelay(1*time.Second), poll.WithTimeout(5*time.Second))
+
+	icmd.RunCommand("docker", "restart", containerID).Assert(t, icmd.Success)
+
+	poll.WaitOn(t, func(t poll.LogT) poll.Result {
+		// if there is another "hi" then the container was successfully restarted,
+		// printed "hi" again and `docker logs` stayed attached
+		if strings.Contains(result.Stdout(), "hi\nhi") { //nolint:dupword
+			return poll.Success()
+		}
+		return poll.Continue(result.Stdout())
+	}, poll.WithDelay(1*time.Second), poll.WithTimeout(10*time.Second))
+
+	icmd.RunCommand("docker", "stop", containerID).Assert(t, icmd.Success)
+
+	icmd.WaitOnCmd(time.Second*10, result).Assert(t, icmd.Expected{
+		ExitCode: 0,
+	})
+}