fixes #27643

Signed-off-by: Ce Gao <ce.gao@outlook.com>

command/service/ps.go

@@ -14,6 +14,7 @@ import (
 
 type psOptions struct {
 	serviceID string
+	quiet     bool
 	noResolve bool
 	noTrunc   bool
 	filter    opts.FilterOpt
@@ -32,6 +33,7 @@ func newPsCommand(dockerCli *command.DockerCli) *cobra.Command {
 		},
 	}
 	flags := cmd.Flags()
+	flags.BoolVarP(&opts.quiet, "quiet", "q", false, "Only display task IDs")
 	flags.BoolVar(&opts.noTrunc, "no-trunc", false, "Do not truncate output")
 	flags.BoolVar(&opts.noResolve, "no-resolve", false, "Do not map IDs to Names")
 	flags.VarP(&opts.filter, "filter", "f", "Filter output based on conditions provided")
@@ -67,5 +69,8 @@ func runPS(dockerCli *command.DockerCli, opts psOptions) error {
 		return err
 	}
 
+	if opts.quiet {
+		return task.PrintQuiet(dockerCli, tasks)
+	}
 	return task.Print(dockerCli, ctx, tasks, idresolver.New(client, opts.noResolve), opts.noTrunc)
 }

command/task/print.go

@@ -2,6 +2,7 @@ package task
 
 import (
 	"fmt"
+	"io"
 	"sort"
 	"strings"
 	"text/tabwriter"
@@ -40,7 +41,9 @@ func (t tasksBySlot) Less(i, j int) bool {
 	return t[j].Meta.CreatedAt.Before(t[i].CreatedAt)
 }
 
-// Print task information in a table format
+// Print task information in a table format.
+// Besides this, command `docker node ps <node>`
+// and `docker stack ps` will call this, too.
 func Print(dockerCli *command.DockerCli, ctx context.Context, tasks []swarm.Task, resolver *idresolver.IDResolver, noTrunc bool) error {
 	sort.Stable(tasksBySlot(tasks))
 
@@ -50,6 +53,27 @@ func Print(dockerCli *command.DockerCli, ctx context.Context, tasks []swarm.Task
 	defer writer.Flush()
 	fmt.Fprintln(writer, strings.Join([]string{"NAME", "IMAGE", "NODE", "DESIRED STATE", "CURRENT STATE", "ERROR"}, "\t"))
 
+	if err := print(writer, ctx, tasks, resolver, noTrunc); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// PrintQuiet shows task list in a quiet way.
+func PrintQuiet(dockerCli *command.DockerCli, tasks []swarm.Task) error {
+	sort.Stable(tasksBySlot(tasks))
+
+	out := dockerCli.Out()
+
+	for _, task := range tasks {
+		fmt.Fprintln(out, task.ID)
+	}
+
+	return nil
+}
+
+func print(out io.Writer, ctx context.Context, tasks []swarm.Task, resolver *idresolver.IDResolver, noTrunc bool) error {
 	prevServiceName := ""
 	prevSlot := 0
 	for _, task := range tasks {
@@ -94,7 +118,7 @@ func Print(dockerCli *command.DockerCli, ctx context.Context, tasks []swarm.Task
 		}
 
 		fmt.Fprintf(
-			writer,
+			out,
 			psTaskItemFmt,
 			indentedName,
 			task.Spec.ContainerSpec.Image,
@@ -105,6 +129,5 @@ func Print(dockerCli *command.DockerCli, ctx context.Context, tasks []swarm.Task
 			taskErr,
 		)
 	}
-
 	return nil
 }