hide --detach for docker < 17.05

Signed-off-by: Victor Vieux <victorvieux@gmail.com>

cli/command/service/helpers.go

@@ -1,18 +1,21 @@
 package service
 
 import (
+	"fmt"
 	"io"
 	"io/ioutil"
 
 	"github.com/docker/cli/cli/command"
 	"github.com/docker/cli/cli/command/service/progress"
+	"github.com/docker/docker/api/types/versions"
 	"github.com/docker/docker/pkg/jsonmessage"
+	"github.com/spf13/pflag"
 	"golang.org/x/net/context"
 )
 
 // waitOnService waits for the service to converge. It outputs a progress bar,
 // if appropriate based on the CLI flags.
-func waitOnService(ctx context.Context, dockerCli *command.DockerCli, serviceID string, opts *serviceOptions) error {
+func waitOnService(ctx context.Context, dockerCli *command.DockerCli, serviceID string, quiet bool) error {
 	errChan := make(chan error, 1)
 	pipeReader, pipeWriter := io.Pipe()
 
@@ -20,7 +23,7 @@ func waitOnService(ctx context.Context, dockerCli *command.DockerCli, serviceID
 		errChan <- progress.ServiceProgress(ctx, dockerCli.Client(), serviceID, pipeWriter)
 	}()
 
-	if opts.quiet {
+	if quiet {
 		go io.Copy(ioutil.Discard, pipeReader)
 		return <-errChan
 	}
@@ -31,3 +34,11 @@ func waitOnService(ctx context.Context, dockerCli *command.DockerCli, serviceID
 	}
 	return err
 }
+
+// warnDetachDefault warns about the --detach flag future change if it's supported.
+func warnDetachDefault(err io.Writer, clientVersion string, flags *pflag.FlagSet, msg string) {
+	if !flags.Changed("detach") && versions.GreaterThanOrEqualTo(clientVersion, "1.29") {
+		fmt.Fprintf(err, "Since --detach=false was not specified, tasks will be %s in the background.\n"+
+			"In a future release, --detach=false will become the default.\n", msg)
+	}
+}