Adopt Cobra completion v2 to support completion by CLI plugins

Signed-off-by: Nicolas De Loof <nicolas.deloof@gmail.com>

cli-plugins/manager/cobra.go

@@ -1,6 +1,9 @@
 package manager
 
 import (
+	"fmt"
+	"os"
+
 	"github.com/docker/cli/cli/command"
 	"github.com/spf13/cobra"
 )
@@ -31,12 +34,13 @@ const (
 // AddPluginCommandStubs adds a stub cobra.Commands for each valid and invalid
 // plugin. The command stubs will have several annotations added, see
 // `CommandAnnotationPlugin*`.
-func AddPluginCommandStubs(dockerCli command.Cli, cmd *cobra.Command) error {
-	plugins, err := ListPlugins(dockerCli, cmd)
+func AddPluginCommandStubs(dockerCli command.Cli, rootCmd *cobra.Command) error {
+	plugins, err := ListPlugins(dockerCli, rootCmd)
 	if err != nil {
 		return err
 	}
 	for _, p := range plugins {
+		p := p
 		vendor := p.Vendor
 		if vendor == "" {
 			vendor = "unknown"
@@ -49,11 +53,41 @@ func AddPluginCommandStubs(dockerCli command.Cli, cmd *cobra.Command) error {
 		if p.Err != nil {
 			annotations[CommandAnnotationPluginInvalid] = p.Err.Error()
 		}
-		cmd.AddCommand(&cobra.Command{
-			Use:         p.Name,
-			Short:       p.ShortDescription,
-			Run:         func(_ *cobra.Command, _ []string) {},
-			Annotations: annotations,
+		rootCmd.AddCommand(&cobra.Command{
+			Use:                p.Name,
+			Short:              p.ShortDescription,
+			Run:                func(_ *cobra.Command, _ []string) {},
+			Annotations:        annotations,
+			DisableFlagParsing: true,
+			RunE: func(cmd *cobra.Command, args []string) error {
+				flags := rootCmd.PersistentFlags()
+				flags.SetOutput(nil)
+				err := flags.Parse(args)
+				if err != nil {
+					return err
+				}
+				if flags.Changed("help") {
+					cmd.HelpFunc()(rootCmd, args)
+					return nil
+				}
+				return fmt.Errorf("docker: '%s' is not a docker command.\nSee 'docker --help'", cmd.Name())
+			},
+			ValidArgsFunction: func(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
+				// Delegate completion to plugin
+				cargs := []string{p.Path, cobra.ShellCompRequestCmd, p.Name}
+				cargs = append(cargs, args...)
+				cargs = append(cargs, toComplete)
+				os.Args = cargs
+				runCommand, err := PluginRunCommand(dockerCli, p.Name, cmd)
+				if err != nil {
+					return nil, cobra.ShellCompDirectiveError
+				}
+				err = runCommand.Run()
+				if err == nil {
+					os.Exit(0) // plugin already rendered complete data
+				}
+				return nil, cobra.ShellCompDirectiveError
+			},
 		})
 	}
 	return nil

cli-plugins/plugin/plugin.go

@@ -125,6 +125,11 @@ func newPluginCommand(dockerCli *command.DockerCli, plugin *cobra.Command, meta
 		},
 		TraverseChildren:      true,
 		DisableFlagsInUseLine: true,
+		CompletionOptions: cobra.CompletionOptions{
+			DisableDefaultCmd:   false,
+			HiddenDefaultCmd:    true,
+			DisableDescriptions: true,
+		},
 	}
 	opts, flags := cli.SetupPluginRootCommand(cmd)